98 results on '"visuo-motor control"'
Search Results
2. Manipulating sensory information: obstacle crossing strategies between typically developing children and young adults.
- Author
-
Rapos, Victoria and Cinelli, Michael
- Subjects
- *
YOUNG adults , *TRAILS , *DYNAMIC stability - Abstract
Individuals constantly adapt their locomotion to navigate through complex environments. However, little known about anticipatory strategies used by children during adaptive locomotion. The purpose of this study was to compare the effects of manipulating visual and somatosensory information during a multiple obstacle crossing task between children and adults. It was hypothesized that compared to young adults, children would have difficulty with anticipatory motor planning and online control during a multiple obstacle crossing task when sensory information was manipulated. Children (N = 16, x ¯ = 9 ± 1.07 years) and young adults (N = 16, x ¯ = 22 ± 0.96 years) walked along a 7 m pathway towards a goal while avoiding stepping on one, or two virtual obstacles placed 5 m from the start. Visual information regarding the number of obstacles was either presented at the start of steady-state locomotion, or two steps prior to the first obstacle. Each participant completed 36 trials, 18 on flat ground and 18 on foam terrain. Results indicated that in comparison to young adults, children's foot positions were significantly closer to the first obstacle when visual information about the obstacle was delayed. On flat ground, children demonstrated similar Trail foot positions relative to the first and second obstacles, suggesting children planned for the avoidance of the obstacles separately. On foam terrain, children performed similar to young adults, such that their Trail foot position relative to the first obstacle was significantly closer to the obstacle compared to their Trial foot position relative to the second obstacle. The results suggest that children plan for the avoidance of multiple obstacles differently compared to young adults. When stability is challenged, maintaining forward progression of locomotion overrides the planning of obstacle crossing, such that children perform similar to young adults. Therefore, it appears that children have difficulties with online control and anticipatory motor strategies during a multiple obstacle crossing task. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
3. Ocular drift reflects volitional action preparation.
- Author
-
Watanabe, Masayuki, Okada, Ken‐ichi, Hamasaki, Yuta, Funamoto, Mari, Kobayashi, Yasushi, MacAskill, Michael, and Anderson, Tim
- Subjects
- *
PUPILLARY reflex , *GLACIAL drift , *EYE movements , *VISUAL perception , *HUMAN behavior - Abstract
Human cognitive behavior is predictive rather than reflexive because of volitional action preparation. Recent studies have shown that the covert process of volitional action preparation can be decoded from overt fixational eye movements of fixational/microsaccades and pupil dilation. Ocular drift, the slowest fixational eye movements, is also under the active neural control, but its relationship with cognitive behavior is unknown. Here, we examined whether ocular drift also reflects volitional action preparation. We analyzed ocular drift while adult humans maintained fixation on a central visual stimulus as they prepared to generate a volitional saccade. We adopted the antisaccade paradigm in which subjects generate a targeting saccade toward the opposite direction of a peripheral visual stimulus. Our findings are the following five points. First, ocular drift was slower when subjects prepared for targeting saccade initiation than when such preparation was unnecessary. Second, ocular drift was slowed down with elapsed time from fixation initiation, which was associated with the facilitation of targeting saccade initiation. Third, ocular drift was further slowed on correct antisaccade trials than when subjects failed to suppress targeting saccades toward peripheral stimuli. Fourth, such correlation with antisaccade performance was observed immediately after fixation initiation in ocular drift, but it emerged more slowly in the other fixational eye movements. Fifth, subjects with unstable fixation because of faster ocular drift had poorer antisaccade performance. We suggest that fixation stability measured by ocular drift can be used to decode the covert process of volitional action preparation along with the other fixational eye movements. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
4. A margin for error in grasping: hand pre-shaping takes into account task-dependent changes in the probability of errors.
- Author
-
Keefe, Bruce D., Suray, Pierre-Arthur, and Watt, Simon J.
- Subjects
- *
ERROR probability , *PREHENSION (Physiology) , *HAND , *ERROR - Abstract
Ideal grasping movements should maintain an appropriate probability of success, while controlling movement-related costs, in the presence of varying visual (and motor) uncertainty. It is often assumed that the probability of errors is managed by adjusting a margin for error in hand opening (e.g., opening the hand wider with increased visual uncertainty). This idea is intuitive, but non-trivial. It implies not only that the brain can estimate the amount of uncertainty, but also that it can compute how different possible alterations to the movement will affect the probability of errors—which we term the 'probability landscape'. Previous work suggests the amount of uncertainty is factored into grasping movements. Our aim was to determine whether grasping movements are also sensitive to the probability landscape. Subjects completed three different grasping tasks, with naturally different probability landscapes, such that appropriate margin-for-error responses to increased uncertainty were qualitatively different (opening the hand wider, the same amount, or less wide). We increased visual uncertainty by blurring vision, and by covering one eye. Movements were performed without visual feedback to isolate uncertainty in the brain's initial estimate of object properties. Changes to hand opening in response to increased visual uncertainty closely resembled those predicted by the margin-for-error account, suggesting that grasping is sensitive to the probability landscape associated with different tasks. Our findings therefore support the intuitive idea that grasping movements employ a true margin-for-error mechanism, which exerts active control over the probability of errors across changing circumstances. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
5. Static versus Adaptive Gain Control Strategy for Visuo-motor Stabilization
- Author
-
Ejaz, Naveed, Tanaka, Reiko J., Krapp, Holger G., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Goebel, Randy, editor, Siekmann, Jörg, editor, Wahlster, Wolfgang, editor, Prescott, Tony J., editor, Lepora, Nathan F., editor, Mura, Anna, editor, and Verschure, Paul F. M. J., editor
- Published
- 2012
- Full Text
- View/download PDF
6. Use-dependent directional bias does not transfer to the untrained limb during bimanual contractions.
- Author
-
Marinovic, Welber, Homan, Melinda, and Carroll, Timothy J.
- Subjects
- *
SENSORIMOTOR integration , *ORIENTATION physiology , *MUSCLE contraction , *PSYCHOLOGY of movement , *PHYSIOLOGY of the anatomical extremities - Abstract
Skills learned through practice with one limb can often be transferred to the untrained limb. In the present report, we sought to determine whether movement direction biases, acquired through repeated movement with one limb, transfer to the untrained limb. In order to do so, we asked participants to perform synchronized bilateral contractions of muscles in both wrists, followed by the unilateral contraction of muscles in one wrist. In four experiments, we manipulated the position of the unilateral target to create use-dependent directional biases; changed the direction of the cursor in relation to the wrist movement to control for attentional biases; and sought to induce directional biases with both right and left unilateral movements. The results showed clear movement-related biases for the wrist that performed unilateral contractions, but no evidence that movement-related bias transferred to the opposite limb during bilateral action. Thus, motor preparation and execution of unilateral contractions does not affect the direction of movement made by the opposite limb during subsequent bilateral contractions. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
7. Viewing geometry determines the contribution of binocular vision to the online control of grasping.
- Author
-
Keefe, Bruce and Watt, Simon
- Subjects
- *
BINOCULAR vision , *SENSORIMOTOR integration , *PREHENSION (Physiology) , *VISUOMOTOR coordination , *MONOCULAR vision - Abstract
Binocular vision is often assumed to make a specific, critical contribution to online visual control of grasping by providing precise information about the separation between digits and object. This account overlooks the 'viewing geometry' typically encountered in grasping, however. Separation of hand and object is rarely aligned precisely with the line of sight (the visual depth dimension), and analysis of the raw signals suggests that, for most other viewing angles, binocular feedback is less precise than monocular feedback. Thus, online grasp control relying selectively on binocular feedback would not be robust to natural changes in viewing geometry. Alternatively, sensory integration theory suggests that different signals contribute according to their relative precision, in which case the role of binocular feedback should depend on viewing geometry, rather than being 'hard-wired'. We manipulated viewing geometry, and assessed the role of binocular feedback by measuring the effects on grasping of occluding one eye at movement onset. Loss of binocular feedback resulted in a significantly less extended final slow-movement phase when hand and object were separated primarily in the frontoparallel plane (where binocular information is relatively imprecise), compared to when they were separated primarily along the line of sight (where binocular information is relatively precise). Consistent with sensory integration theory, this suggests the role of binocular (and monocular) vision in online grasp control is not a fixed, 'architectural' property of the visuo-motor system, but arises instead from the interaction of viewer and situation, allowing robust online control across natural variations in viewing geometry. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
8. The pointing errors in optic ataxia reveal the role of 'peripheral magnification' of the PPC
- Author
-
Philippe Vindras, Annabelle Blangero, Hisaaki Ota, Karen T. Reilly, Yves Rossetti, and Laure Pisella
- Subjects
mathematical modeling ,Posterior parietal cortex ,peripheral vision ,visuo-motor control ,Models, Theoretical ,optic ataxia ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Interaction with visual objects in the environment requires an accurate correspondence between visual space and its internal representation within the brain. Many clinical conditions involve some impairment in visuo-motor control and the errors created by the lesion of a specific brain region are neither random nor uninformative. Modern approaches to studying the neuropsychology of action require powerful data-driven analyses and error modelling in order to understand the function of the lesioned areas. In the present paper we carried out mixed-effect analyses of the pointing errors of seven optic ataxia patients and seven control subjects. We found that a small parameter set is sufficient to explain the pointing errors produced by unilateral optic ataxia patients. In particular, the extremely stereotypical errors made when pointing toward the contralesional visual field can be fitted by mathematical models similar to those used to model central magnification in cortical or sub-cortical structure(s). Our interpretation is that visual areas that contain this footprint of central magnification guide pointing movements when the posterior parietal cortex is damaged and that the functional role of the posterior parietal cortex is to actively compensate for the under-representation of peripheral vision that accompanies central magnification. Optic ataxia misreaching reveals what would be hand movement accuracy and precision if the human motor system did not include elaborated corrective processes for reaching and grasping to non-foveated targets.
- Published
- 2016
- Full Text
- View/download PDF
9. The Pointing Errors in Optic Ataxia Reveal the Role of "Peripheral Magnification" of the PPC.
- Author
-
Vindras, Philippe, Blangero, Annabelle, Hisaaki Ota, Reilly, Karen T., Rossetti, Yves, and Pisella, Laure
- Subjects
CEREBRAL cortex abnormalities ,MAGNIFICATION (Optics) ,PERIPHERAL vision - Abstract
Interaction with visual objects in the environment requires an accurate correspondence between visual space and its internal representation within the brain. Many clinical conditions involve some impairment in visuo-motor control and the errors created by the lesion of a specific brain region are neither random nor uninformative. Modern approaches to studying the neuropsychology of action require powerful data-driven analyses and error modeling in order to understand the function of the lesioned areas. In the present paper we carried out mixed-effect analyses of the pointing errors of seven optic ataxia patients and seven control subjects. We found that a small parameter set is sufficient to explain the pointing errors produced by unilateral optic ataxia patients. In particular, the extremely stereotypical errors made when pointing toward the contralesional visual field can be fitted by mathematical models similar to those used to model central magnification in cortical or sub-cortical structure(s). Our interpretation is that visual areas that contain this footprint of central magnification guide pointing movements when the posterior parietal cortex (PPC) is damaged and that the functional role of the PPC is to actively compensate for the under-representation of peripheral vision that accompanies central magnification. Optic ataxia misreaching reveals what would be hand movement accuracy and precision if the human motor system did not include elaborated corrective processes for reaching and grasping to non-foveated targets. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
10. Grasping objects by former amputees: The visuo-motor control of allografted hands.
- Author
-
Huchon, Laure, Badet, Lionel, Roy, Alice Catherine, Finos, Livio, Gazarian, Aram, Revol, Patrice, Bernardon, Laurence, Rossetti, Yves, Morelon, Emmanuel, Rode, Gilles, and Farnè, Alessandro
- Subjects
- *
ACQUISITIVENESS , *AMPUTEES , *HOMOGRAFTS , *BRAIN imaging , *SENSORIMOTOR integration - Abstract
Purpose: Hand allograft has recently emerged as a therapeutic option for upper limb amputees. Functional neuroimaging studies have progressively revealed sensorimotor cortices plasticity following both amputation and transplantation. The purpose of our study was to assess and characterize the functional recovery of the visuo-motor control of prehension in bilateral hand transplanted patients. Methods: Using kinematics recordings, we characterized the performance of prehension with or without visual feed-back for object of different position and size, in five bilateral hand allograft recipients and age-matched control subjects. Both hands were assessed, separately. Results: Despite an overall slower execution, allografted patients succeeded in grasping for more than 90% of the trials. They exhibited a preserved hand grip scaling according to object size, and preserved prehension performances when tested without visual feedback. These findings highlight the allograft recipients' abilities to produce an effective motor program, and a good proprioceptive-dependent online control. Nevertheless, the maximum grip aperture was reduced and delayed, the coupling between Transport and Grasp components was altered, and the final phase of the movement was lengthened. Conclusion: Hand allotransplantation can offer recipients a good recovery of the visuo-motor control of prehension, with slight impairments likely attributable to peripheral neuro-orthopedic limitations. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
11. Visuomotor control of 3D circular tracking movement in a virtual reality space.
- Author
-
Choi, W., Li, L., and Lee, J. H.
- Subjects
VIRTUAL reality ,CONFERENCES & conventions ,VISUAL perception ,MOTOR ability ,SPACE perception - Abstract
Purpose The progress of learning human movements and motor control mechanisms by observing and imitating human movements was based on visuomotor control in three-dimensional (3D) space. However, previous studies of motion control in 3D space have focused on analyzing tracking tasks along 1D lines or 2D planes using single or multi-joint movements. In this study, we propose a visuomotor system for quantitatively evaluating visuomotor control in a 3D space based on virtual reality (VR) (Choi (2018)). The proposed system has been designed to analyze 3D circular tracking motions on frontal and sagittal planes of VR space. Furthermore, we analyzed two types of 3D target tracking tasks to verify the effectiveness of our system, the 3D circular tracking movements from the frontal plane to the body and the circular tracking movements from the sagittal plane to the body. In addition, we compared visuomotor control in 3D circular tracking motion between monocular without depth and binocular vision with depth. Method The system allowed users to conduct the 3D visually-guided tracking movement in the 3D VR space (Figure 1). We established the size of the 3D target as 1.5 times larger than the 3D tracer in this research. The 3D target has a red ball with a radius of 1.5 cm. The 3D tracer has a yellow ball with a radius of 1 cm placed at the tip of the 3D stick. Instead of users' own hands in VR space, the hands were shown the 3D stick. Each task was carried out with the 3D target rotating on the frontal plane (ROTO in Figure 1(A)) and on the sagittal plane (ROT90 in Figure 1(B)). We transformed the data of the X, Y, and Z to "R" displacement, "ϑ" angular displacement, and "ω" angular velocity on polar coordinates. We analyzed the differences of 3D circular tracking movements based on the parameters of ΔR, Δϑ, and Δω in VR space (Choi (2020)). Results and Discussion We developed a system that allows users to quantitatively evaluate visuomotor movement based on 3D target tracking in a 3D virtual reality space. It is verified that 3D visuomotor control under monocular and binocular conditions could be analyzed quantitatively. We found that the tracking system is more useful to adopt the parameters of Δϑ, and Δω to analyze the circular tracking movement with increasing speed. In addition, we also found that the parameter of ΔR was not suitable for the analysis of low-speed movement. When tracking movement, we also found that the visual dependence was large and had a great influence on the accuracy of the movement. The proposed system can be useful for assessing the severity of the disease and the rehabilitation of people with hemiplegic upper arms. The proposed system can also quantitatively measure the performance of the visuomotor control system of aging adults and create a database of the visuomotor control. This study will contribute to a basic research to analyze the changes of the visuomotor control system that occur with aging and to present an appropriate motor learning model for aging adults. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
12. Color perception is impaired in baseball batters while performing an interceptive action.
- Author
-
Sasada, Manami, Nakamoto, Hiroki, Ikudome, Sachi, Unenaka, Satoshi, and Mori, Shiro
- Subjects
- *
COLOR vision , *DESIGNATED hitters (Baseball) , *BASEBALL players , *VISUAL perception , *VISUOMOTOR coordination - Abstract
In order to test the theoretical idea that experts rely more on the dorsal stream than the ventral stream during interceptive action for the interception of a moving target, the present study investigates the perception of color (dominant in ventral processing) during interceptive action in fast-ball sports. Twelve college baseball players and 12 non-baseball players performed a coincident-timing task with target color changes (from white to red, blue, or white) at various time points (at 100, 200, or 300 ms before target arrival). In this task, participants swung a bat and/or pressed a button in response to the target's arrival at a prespecified location. Participants were then asked to state the final color of the target. Baseball players, but not non-baseball players, were significantly less proficient at identifying color changes during the bat-swing condition relative to the button-press condition, irrespective of the time points of color change. These results are consistent with the idea that baseball players rely more on the dorsal stream during bat swinging for the interception of a moving target than do novices. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
13. Effects of sport expertise on representational momentum during timing control.
- Author
-
Nakamoto, Hiroki, Mori, Shiro, Ikudome, Sachi, Unenaka, Satoshi, and Imanaka, Kuniyasu
- Subjects
- *
EXPERTISE , *ATHLETIC ability , *VISUAL perception , *COGNITION , *VISUOMOTOR coordination , *REACTION time - Abstract
Sports involving fast visual perception require players to compensate for delays in neural processing of visual information. Memory for the final position of a moving object is distorted forward along its path of motion (i.e., 'representational momentum,' RM). This cognitive extrapolation of visual perception might compensate for the neural delay in interacting appropriately with a moving object. The present study examined whether experienced batters cognitively extrapolate the location of a fast-moving object and whether this extrapolation is associated with coincident timing control. Nine expert and nine novice baseball players performed a prediction motion task in which a target moved from one end of a straight 400-cm track at a constant velocity. In half of the trials, vision was suddenly occluded when the target reached the 200-cm point (occlusion condition). Participants had to press a button concurrently with the target arrival at the end of the track and verbally report their subjective assessment of the first target-occluded position. Experts showed larger RM magnitude (cognitive extrapolation) than did novices in the occlusion condition. RM magnitude and timing errors were strongly correlated in the fast velocity condition in both experts and novices, whereas in the slow velocity condition, a significant correlation appeared only in experts. This suggests that experts can cognitively extrapolate the location of a moving object according to their anticipation and, as a result, potentially circumvent neural processing delays. This process might be used to control response timing when interacting with moving objects. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
14. The effect of temporal perception on weight perception
- Author
-
Hiroyuki eKambara, Duk eShin, Toshihiro eKawase, Natsue eYoshimura, Katsuhito eAkahane, Makoto eSato, and Yasuharu eKoike
- Subjects
Weight Perception ,motor adaptation ,temporal adaptation ,Temporal Perception ,visuo-motor control ,force illusion ,Psychology ,BF1-990 - Abstract
A successful catch of a falling ball requires an accurate estimation of the timing for when the ball hits the hand. In a previous experiments in which participants performed ball-catching task in virtual reality environment, we accidentally found that the weight of a falling ball was perceived differently when the timing of ball load force to the hand was shifted from the timing expected from visual information. Although it is well known that spatial information of an object, such as size, can easily deceive our perception of its heaviness, the relationship between temporal information and perceived heaviness is still not clear. In this study, we investigated the effect of temporal factors on weight perception. We conducted ball-catching experiments in a virtual environment where the timing of load force exertion was shifted away from the visual contact timing (i.e., time when the ball hit the hand in the display). We found that the ball was perceived heavier when force was applied earlier than visual contact and lighter when force was applied after visual contact. We also conducted additional experiments in which participants were conditioned to one of two constant time offsets prior to testing weight perception. After performing ball-catching trials with 60 ms advanced or delayed load force exertion, participants' subjective judgment on the simultaneity of visual contact and force exertion changed, reflecting a shift in perception of time offset. In addition, timing of catching motion initiation relative to visual contact changed, reflecting a shift in estimation of force timing. We also found that participants began to perceive the ball as lighter after conditioning to 60 ms advanced offset and heavier after the 60 ms delayed offset. These results suggest that perceived heaviness depends not on the actual time offset between force exertion and visual contact but on the subjectively perceived time offset between them and/or estimation error in force timing.
- Published
- 2013
- Full Text
- View/download PDF
15. An External Focus of Attention Enhances Manual Tracking of Occluded and Visible Targets
- Author
-
Matthew eSchlesinger, Jared ePorter, and Robert eRussell
- Subjects
spatial working memory ,Focus of attention ,visuo-motor control ,manual tracking ,occluded motion perception ,Psychology ,BF1-990 - Abstract
The present study investigated the enhancement effects of an external focus-of-attention (FOA) in the context of a manual-tracking task, in which participants tracked both visible and occluded targets. Three conditions were compared, which manipulated the distance of the FOA from the participant as well as the external/internal dimension. As expected, an external FOA resulted in lower tracking errors than an internal FOA. In addition, analyses of participants' movement patterns revealed a systematic shift toward higher-frequency movements in the external FOA condition, consistent with the idea that an external FOA exploits the natural movement dynamics available during skilled action. Finally, target visibility did not influence the effect of focused attention on tracking performance, which provides evidence for the proposal that the mechanisms that underlie FOA do not depend directly on vision.
- Published
- 2013
- Full Text
- View/download PDF
16. On the mechanisms underlying Prism Adaptation: A review of neuro-imaging and neuro-stimulation studies
- Author
-
Yves Rossetti, Francesco Panico, Luigi Trojano, Panico, F., Rossetti, Y., and Trojano, L.
- Subjects
Prism Adaptation ,Cognitive Neuroscience ,media_common.quotation_subject ,Experimental and Cognitive Psychology ,050105 experimental psychology ,Functional Laterality ,Neglect ,Task (project management) ,Perceptual Disorders ,03 medical and health sciences ,0302 clinical medicine ,Cognition ,Neuroimaging ,Cerebellum ,medicine ,Humans ,0501 psychology and cognitive sciences ,media_common ,05 social sciences ,Brain ,Spatial cognition ,Spatial attention ,Neuro-imaging ,Adaptation, Physiological ,Neuropsychology and Physiological Psychology ,medicine.anatomical_structure ,Brain stimulation ,Space Perception ,Psychology ,Neuroscience ,Prism adaptation ,Visuo-motor control ,030217 neurology & neurosurgery ,Motor cortex - Abstract
Prism Adaptation (PA) is a behavioral task to assess visuo-motor plasticity and to ameliorate the symptoms of unilateral spatial neglect. Several studies have addressed the effects of PA on both sensory-motor and cognitive processing and the contribution of different brain regions to PA, although via non standardized procedures. The aim of the present review is to gather findings from the neuro-imaging and neuro-stimulation fields and put forward an interpretative framework for PA. The available evidence supports that sensory-motor effects of PA would mainly relate to the activation of a cerebello-parietal network, while the effects on spatial cognition would be mediated by bottom-up activation of temporal and prefrontal regions. The consolidation of PA effects would rely on activity of the motor cortex. The use of standardized PA procedures is strongly recommended for a systematic and accurate investigation of the neural mechanisms of PA.
- Published
- 2020
17. The VODKA Sensor: A Bio-Inspired Hyperacute Optical Position Sensing Device.
- Author
-
Kerhuel, L., Viollet, S., and Franceschini, N.
- Abstract
We have designed and built a simple optical sensor called Vibrating Optical Device for the Kontrol of Autonomous robots (VODKA), that was inspired by the “tremor” eye movements observed in many vertebrate and invertebrate animals. In the initial version presented here, the sensor relies on the repetitive micro-translation of a pair of photoreceptors set behind a small lens, and on the processing designed to locate a target from the two photoreceptor signals. The VODKA sensor, in which retinal micro-scanning movements are performed via a small piezo-bender actuator driven at a frequency of 40 Hz, was found to be able to locate a contrasting edge with an outstandingly high resolution 900-fold greater than its static resolution (which is constrained by the interreceptor angle), regardless of the scanning law imposed on the retina. Hyperacuity is thus obtained at a very low cost, thus opening new vistas for the accurate visuo-motor control of robotic platforms. As an example, the sensor was mounted onto a miniature aerial robot that became able to track a moving target accurately by exploiting the robot's uncontrolled random vibrations as the source of its ocular microscanning movement. The simplicity, small size, low mass and low power consumption of this optical sensor make it highly suitable for many applications in the fields of metrology, astronomy, robotics, automotive, and aerospace engineering. The basic operating principle may also shed new light on the whys and wherefores of the tremor eye movements occurring in both animals and humans. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
18. Development of human visual function
- Author
-
Braddick, Oliver and Atkinson, Janette
- Subjects
- *
VISUAL acuity , *CONTRAST sensitivity (Vision) , *EVOKED potentials (Electrophysiology) , *EYE movements , *INFANT care , *OPHTHALMOLOGY , *PEDIATRIC neurology ,VISION research - Abstract
Abstract: By 1985 newly devised behavioural and electrophysiological techniques had been used to track development of infants’ acuity, contrast sensitivity and binocularity, and for clinical evaluation of developing visual function. This review focusses on advances in the development and assessment of infant vision in the following 25years. Infants’ visual cortical function has been studied through selectivity for orientation, directional motion and binocular disparity, and the control of subcortical oculomotor mechanisms in fixation shifts and optokinetic nystagmus, leading to a model of increasing cortical dominance over subcortical pathways. Neonatal face processing remains a challenge for this model. Recent research has focussed on development of integrative processing (hyperacuity, texture segmentation, and sensitivity to global form and motion coherence) in extra-striate visual areas, including signatures of dorsal and ventral stream processing. Asynchronies in development of these two streams may be related to their differential vulnerability in both acquired and genetic disorders. New methods and approaches to clinical disorders are reviewed, in particular the increasing focus on paediatric neurology as well as ophthalmology. Visual measures in early infancy in high-risk children are allowing measures not only of existing deficits in infancy but prediction of later visual and cognitive outcome. Work with early cataract and later recovery from blinding disorders has thrown new light on the plasticity of the visual system and its limitations. The review concludes with a forward look to future opportunities provided by studies of development post infancy, new imaging and eye tracking methods, and sampling infants’ visual ecology. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
19. Depth-cue integration in grasp programming: No evidence for a binocular specialism
- Author
-
Keefe, Bruce D., Hibbard, Paul B., and Watt, Simon J.
- Subjects
- *
ACQUISITIVENESS , *BINOCULAR vision , *VISUAL perception , *AGNOSIA , *EYE movements , *PSYCHOPHYSICS , *UNCERTAINTY - Abstract
Abstract: When we grasp with one eye covered, the finger and thumb are typically opened wider than for binocularly guided grasps, as if to build a margin-for-error into the movement. Also, patients with visual form agnosia can have profound deficits in their (otherwise relatively normal) grasping when binocular information is removed. One interpretation of these findings is that there is a functional specialism for binocular vision in the control of grasping. Alternatively, cue-integration theory suggests that binocular and monocular depth cues are combined in the control of grasping, and so impaired performance reflects not the loss of ‘critical’ binocular cues, but increased uncertainty per se. Unfortunately, removing binocular information confounds removing particular (binocular) depth cues with an overall reduction in the available information, and so such experiments cannot distinguish between these alternatives. We measured the effects on visually open-loop grasping of selectively removing monocular (texture) or binocular depth cues. To allow meaningful comparisons, we made psychophysical measurements of the uncertainty in size estimates in each case, so that the informativeness of binocular and monocular cues was known in each condition. Consistent with cue-integration theory, removing either binocular or monocular cues resulted in similar increases in grip apertures. In a separate experiment, we also confirmed that changes in uncertainty per se (keeping the same depth cues available) resulted in larger grip apertures. Overall, changes in the margin-for-error in grasping movements were determined by the uncertainty in size estimates and not by the presence or absence of particular depth cues. Our data therefore argue against a binocular specialism for grasp programming. Instead, grip apertures were smaller when binocular and monocular cues were available than with either cue alone, providing strong evidence that the visuo-motor system exploits the redundancy available in multiple sources of information, and integrates binocular and monocular cues to improve grasping performance. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
20. The influence of quiet eye training and pressure on attention and visuo-motor control
- Author
-
Vine, Samuel J. and Wilson, Mark R.
- Subjects
- *
ATTENTION , *VISUAL perception , *MOTOR learning , *ANXIETY , *DISTRACTION , *COMPARATIVE studies - Abstract
Abstract: The aim of this study was to examine the efficacy of an intervention designed to train effective visual attentional control (quiet eye-training) for a far aiming skill, and determine whether such training protected against attentional disruptions associated with performing under pressure. Sixteen novice participants wore a mobile eye-tracker to assess their visual attentional control (quiet eye) during the completion of 520 basketball free throws carried out over 8days. They first performed 40 pre-test free throws and were randomly allocated into a quiet eye (QE) training or Control group (technical instruction only). Participants then performed 360 free throws during a training period and a further 120 test free throws under conditions designed to manipulate the level of anxiety experienced. The QE trained group maintained more effective visual attentional control and performed significantly better in the pressure test compared to the Control group, providing support for the efficacy of attentional training for visuo-motor skills. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
21. Dissociation of extrastriate body and biological-motion selective areas by manipulation of visual-motor congruency
- Author
-
Kontaris, Ioannis, Wiggett, Alison J., and Downing, Paul E.
- Subjects
- *
BRAIN function localization , *VISUAL perception , *MOTION perception (Vision) , *MAGNETIC resonance imaging of the brain , *BRAIN anatomy , *MOTOR cortex - Abstract
Abstract: To date, several posterior brain regions have been identified that play a role in the visual perception of other people and their movements. The aim of the present study is to understand how these areas may be involved in relating body movements to their visual consequences. We used fMRI to examine the extrastriate body area (EBA), the fusiform body area (FBA), and an area in the posterior superior temporal sulcus (pSTS) that responds to patterns of human biological motion. Each area was localized in individual participants with independent scans. In the main experiment, participants performed and/or viewed simple, intransitive hand actions while in the scanner. An MR-compatible camera with a near-egocentric view of the participant''s hand was used to manipulate the relationship between motor output and the visual stimulus. Participants’ only view of their hands was via this camera. In the Compatible condition, participants viewed their own live hand movements projected onto the screen. In the Incompatible condition, participants viewed actions that were different from the actions they were executing. In pSTS, the BOLD response in the Incompatible condition was significantly higher than in the Compatible condition. Further, the response in the Compatible condition was below baseline, and no greater than that found in a control condition in which hand actions were performed without any visual input. This indicates a strong suppression in pSTS of the response to the visual stimulus that arises from one''s own actions. In contrast, in EBA and FBA, we found a large but equivalent response to the Compatible and Incompatible conditions, and this response was the same as that elicited in a control condition in which hand actions were viewed passively, with no concurrent motor task. These findings indicate that, in contrast to pSTS, EBA and FBA are decoupled from motor systems. Instead we propose that their role is limited to perceptual analysis of body-related visual input. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
22. Background luminance affects the detection of microampere currents delivered to macaque striate cortex.
- Author
-
Tehovnik, Edward J. and Slocum, Warren M.
- Subjects
- *
ELECTRIC stimulation , *VISUAL cortex , *MONKEYS , *AFTER-images , *VISUAL perception , *APPLE juice - Abstract
Monkeys detect electrical microstimulation delivered to the striate cortex (area V1). We examined whether the ability of monkeys to detect such stimulation is affected by background luminance. While remaining fixated on a spot of light centered on a monitor, a monkey was required to detect a 100 ms train of electrical stimulation delivered to a site within area V1 situated from 1 to 1.5 mm below the cortical surface. A monkey signaled the delivery of stimulation by depressing a lever after which it was rewarded with a drop of apple juice. Control trials were interleaved during which time no stimulation was delivered and the monkey was rewarded for not depressing the lever. Biphasic pulses were delivered at 200 Hz and the current ranged from 2 to 30 μA using 0.2 ms anode-first biphasic pulses. The background luminance level of the monitor could be varied from 0.005 to 148 cd/m2. It was found that, for monitor luminance levels below 10 cd/m2, the current threshold to evoke a detection response increased. We discuss the significance of this result with regard to phosphenes elicited from human V1 and in relation to visual perception. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
23. The role of binocular vision in grasping: a small stimulus-set distorts results.
- Author
-
Keefe, Bruce D. and Watt, Simon J.
- Subjects
- *
BINOCULAR vision , *ACQUISITIVENESS , *KINEMATICS , *STIMULUS generalization , *SENSES - Abstract
The role of binocular vision in grasping has frequently been assessed by measuring the effects on grasp kinematics of covering one eye. These studies have typically used three or fewer objects presented at three or fewer distances, raising the possibility that participants learn the properties of the stimulus set. If so, even relatively poor visual information may be sufficient to identify which object/distance configuration is presented on a given trial, in effect providing an additional source of depth information. Here we show that the availability of this uncontrolled cue leads to an underestimate of the effects of removing binocular information, and therefore to an overestimate of the effectiveness of the remaining cues. We measured the effects of removing binocular cues on visually open-loop grasps using (1) a conventional small stimulus-set, and (2) a large, pseudo-randomised stimulus set, which could not be learned. Removing binocular cues resulted in a significant change in grip aperture scaling in both conditions: peak grip apertures were larger (when reaching to small objects), and scaled less with increases in object size. However, this effect was significantly larger with the randomised stimulus set. These results confirm that binocular information makes a significant contribution to grasp planning. Moreover, they suggest that learned stimulus information can contribute to grasping in typical experiments, and so the contribution of information from binocular vision (and from other depth cues) may not have been measured accurately. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
24. The Use of Prescanning in the Parameterization of Sequential Pointing and Reaching Movements.
- Author
-
Wilmut, Kate and Wann, John
- Subjects
- *
VISUAL perception , *SOMATIC sensation , *EYE-hand coordination , *MOTOR ability , *POINTING (Gesture) , *GAZE , *PHYSIOLOGY - Abstract
The accuracy of reaching movements improves when active gaze can be used to fixate on targets. The advantage of free gaze has been attributed to the use of ocular proprioception or efference signals for online control. The time course of this process, however, is not established, and it is unclear how far in advance gaze can move and still be used to parameterize subsequent movements. In this experiment, the authors considered the advantage of prescanning targets for both pointing and reaching movements. The authors manipulated the visual information and examined the extent to which prescanning of targets could compensate for a reduction in online visual feedback. In comparison with a conventional reaching/pointing condition, the error in pointing was reduced, the eye-hand lead decreased, and both the hand-closure time and the size of the maximum grip aperture in reaching were modulated when prescanning was allowed. These results indicate that briefly prescanning multiple targets just prior to the movement allows the refinement of subsequent hand movements that yields an improvement in accuracy. This study therefore provides additional evidence that the coordinate information arising from efference or ocular-proprioceptive signals can, for a limited period, be buffered and later used to generate a sequence of movements. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
25. Internal models and prediction of visual gravitational motion
- Author
-
Zago, Myrka, McIntyre, Joseph, Senot, Patrice, and Lacquaniti, Francesco
- Subjects
- *
VISUAL perception , *VISION , *RESEARCH , *GRAVITY - Abstract
Abstract: Baurès et al. [Baurès, R., Benguigui, N., Amorim, M.-A., & Siegler, I. A. (2007). Intercepting free falling objects: Better use Occam’s razor than internalize Newton’s law. Vision Research, 47, 2982–2991] rejected the hypothesis that free-falling objects are intercepted using a predictive model of gravity. They argued instead for “a continuous guide for action timing” based on visual information updated till target capture. Here we show that their arguments are flawed, because they fail to consider the impact of sensori-motor delays on interception behaviour and the need for neural compensation of such delays. When intercepting a free-falling object, the delays can be overcome by a predictive model of the effects of gravity on target motion. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
26. Visual and musculoskeletal underpinnings of anchoring in rhythmic visuo-motor tracking.
- Author
-
Roerdink, Melvyn, Ophoff, Ellen, (Lieke) E. Peper, C., and Beek, Peter
- Subjects
- *
MUSCULOSKELETAL system , *VISUAL perception , *SENSORIMOTOR integration , *CEREBRAL cortex , *SENSORIMOTOR cortex , *SENSORY processing disorder - Abstract
Anchoring, that is, a local reduction in kinematic (i.e., spatio-temporal) variability, is commonly observed in cyclical movements, often at or around reversal points. Two kinds of underpinnings of anchoring have been identified—visual and musculoskeletal—yet their relative contributions and interrelations are largely unknown. We conducted an experiment to delineate the effects of visual and musculoskeletal factors on anchoring behavior in visuo-motor tracking. Thirteen participants (reduced to 12 in the analyses) tracked a sinusoidally moving visual target signal by making flexion–extension movements about the wrist, while both visual (i.e., gaze direction) and musculoskeletal (i.e., wrist posture) factors were manipulated in a fully crossed (3 × 3) design. Anchoring was affected by both factors in the absence of any significant interactions, implying that their contributions were independent. When gaze was directed to one of the target turning points, spatial endpoint variability at this point was reduced, but not temporal endpoint variability. With the wrist in a flexed posture, spatial and temporal endpoint variability were both smaller for the flexion endpoint than for the extension endpoint, while the converse was true for tracking with the wrist extended. Differential anchoring effects were absent for a neutral wrist posture and when gaze was fixated in between the two target turning points. Detailed analyses of the tracking trajectories in terms of velocity profiles and Hooke’s portraits showed that the tracking dynamics were affected more by wrist posture than by gaze direction. The discussion focuses on the processes underlying the observed independent effects of gaze direction and wrist posture on anchoring as well as their implications for the notion of anchoring as a generic feature of sensorimotor coordination. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
27. On the timing of reference frames for action control.
- Author
-
Fischer, Martin H., Pratt, Jay, and Adam, Jos J.
- Subjects
- *
MOTOR ability , *HUMAN mechanics , *VISION , *BRAIN research , *NEUROBIOLOGY - Abstract
This study investigated the time course and automaticity of spatial coding of visual targets for pointing movements. To provide an allocentric reference, placeholders appeared on a touch screen either 500 ms before target onset, or simultaneously with target onset, or at movement onset, or not at all (baseline). With both blocked and randomized placeholder timing, movements to the most distant targets were only facilitated when placeholders were visible before movement onset. This result suggests that allocentric target coding is most useful during movement planning and that this visuo-spatial coding mechanism is not sensitive to strategic effects. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
28. Viewing geometry determines the contribution of binocular vision to the online control of grasping
- Author
-
Simon J. Watt and Bruce Keefe
- Subjects
Adult ,Male ,Grasping ,Time Factors ,genetic structures ,Online control ,Computer science ,Property (programming) ,Movement ,Geometry ,Sensory system ,Visual control ,Online Systems ,050105 experimental psychology ,Sensory integration ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Feedback, Sensory ,Humans ,0501 psychology and cognitive sciences ,Vision, Binocular ,Monocular ,Hand Strength ,General Neuroscience ,05 social sciences ,GRASP ,Middle Aged ,Wrist ,Object (philosophy) ,Visual feedback ,eye diseases ,Visual Perception ,Binocular disparity ,Female ,Binocular vision ,Visuo-motor control ,030217 neurology & neurosurgery ,Photic Stimulation ,Psychomotor Performance ,Research Article - Abstract
Binocular vision is often assumed to make a specific, critical contribution to online visual control of grasping by providing precise information about the separation between digits and object. This account overlooks the ‘viewing geometry’ typically encountered in grasping, however. Separation of hand and object is rarely aligned precisely with the line of sight (the visual depth dimension), and analysis of the raw signals suggests that, for most other viewing angles, binocular feedback is less precise than monocular feedback. Thus, online grasp control relying selectively on binocular feedback would not be robust to natural changes in viewing geometry. Alternatively, sensory integration theory suggests that different signals contribute according to their relative precision, in which case the role of binocular feedback should depend on viewing geometry, rather than being ‘hard-wired’. We manipulated viewing geometry, and assessed the role of binocular feedback by measuring the effects on grasping of occluding one eye at movement onset. Loss of binocular feedback resulted in a significantly less extended final slow-movement phase when hand and object were separated primarily in the frontoparallel plane (where binocular information is relatively imprecise), compared to when they were separated primarily along the line of sight (where binocular information is relatively precise). Consistent with sensory integration theory, this suggests the role of binocular (and monocular) vision in online grasp control is not a fixed, ‘architectural’ property of the visuo-motor system, but arises instead from the interaction of viewer and situation, allowing robust online control across natural variations in viewing geometry. Electronic supplementary material The online version of this article (doi:10.1007/s00221-017-5087-0) contains supplementary material, which is available to authorized users.
- Published
- 2017
29. How active gaze informs the hand in sequential pointing movements.
- Author
-
Wilmut, Kate, Wann, John P., and Brown, Janice H.
- Subjects
- *
GAZE , *VISUAL perception , *EYE movements , *HUMAN mechanics , *SACCADIC eye movements - Abstract
Visual information is vital for fast and accurate hand movements. It has been demonstrated that allowing free eye movements results in greater accuracy than when the eyes maintain centrally fixed. Three explanations as to why free gaze improves accuracy are: shifting gaze to a target allows visual feedback in guiding the hand to the target (feedback loop), shifting gaze generates ocular-proprioception which can be used to update a movement (feedback–feedforward), or efference copy could be used to direct hand movements (feedforward). In this experiment we used a double-step task and manipulated the utility of ocular-proprioceptive feedback from eye to head position by removing the second target during the saccade. We confirm the advantage of free gaze for sequential movements with a double-step pointing task and document eye–hand lead times of approximately 200 ms for both initial movements and secondary movements. The observation that participants move gaze well ahead of the current hand target dismisses foveal feedback as a major contribution. We argue for a feedforward model based on eye movement efference as the major factor in enabling accurate hand movements. The results with the double-step target task also suggest the need for some buffering of efference and ocular-proprioceptive signals to cope with the situation where the eye has moved to a location ahead of the current target for the hand movement. We estimate that this buffer period may range between 120 and 200 ms without significant impact on hand movement accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
30. Limits to human movement planning with delayed and unpredictable onset of needed information.
- Author
-
Trommershäuser, Julia, Mattis, Joanna, Maloney, Laurence T., and Landy, Michael S.
- Subjects
- *
MOTION perception (Vision) , *MOVEMENT sequences , *VISUAL evoked response , *DECISION theory , *REACTION time , *KINEMATICS - Abstract
In motor tasks with explicit rewards and penalties, humans choose movement strategies that nearly maximize expected gain (Trommershäuser et al. in J Opt Soc Am A 20:1419–1433, ). Here, we examine whether performance is still close to optimal when information about payoffs is not available prior to movement onset. Subjects rapidly touched a target region while trying to avoid hitting an overlapping penalty region placed randomly to the left or right of the target. Subjects received rewards and incurred penalties for hitting the corresponding regions. Late responses (>700 ms) were heavily penalized. The penalty region was displayed 0, 200 or 400 ms after the reward region and the subject could not know where it would be until then. Reaction times to begin the movement after stimulus appearance were constant across conditions. Median reaction times were approximately 200 ms, i.e., the time the penalty was first displayed in the 200 ms delay condition. Performance was compared to that of an optimal movement planner that chooses mean end points to maximize expected gain despite movement variability. In the 0 and 200 ms delay conditions, subjects selected strategies that did not differ significantly from optimal, indicating that humans are able to plan their movements well despite delayed and unpredictable onset of information. Performance dropped below optimal in the 400 ms delay condition, with mean movement end points closer to the penalty region than predicted by the optimal strategy (in the high-penalty condition). We conclude that relevant information concerning the reward structure is required between 200 and 400 ms prior to the end of the movement, but can still be integrated into the movement plan after movement initiation. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
31. Preserved prism adaptation in bilateral optic ataxia: strategic versus adaptive reaction to prisms.
- Author
-
Pisella, L., Michel, C., Gréa, H., Tilikete, C., Vighetto, A., and Rossetti, Y.
- Subjects
- *
CEREBELLUM diseases , *CEREBRAL cortex , *PRISMS (Ophthalmology) , *PHYSIOLOGICAL adaptation , *ATAXIA telangiectasia , *CEREBELLUM - Abstract
To date the anatomical substrate(s) of prism adaptation remain(s) particularly debated, with two main candidates emerging from the literature: the posterior parietal cortex (PPC) and the cerebellum. The functional processes involved in the acquisition of the adaptive aftereffects also remain largely unknown. The main result shown here is that a patient with a bilateral optic ataxia can adapt to an optical deviation, which allows us to make a step forward on these two issues. First, it demonstrates that the corresponding part of the PPC is not a necessary substrate for prism adaptation. Second, since this patient exhibits deficit for fast visuo-motor guidance, it provides direct evidence for a dissociation between on-line visuo-motor control and visuo-motor plasticity. Since the intermanual transfer rate of adaptation is larger in this patient than in control subjects, the PPC may still have an influence on adaptation under normal conditions. We propose a model of the relative contribution of the PPC and the cerebellum during prism exposure, associating these two structures with the two interacting behavioural components of prism adaptation described by previous psychophysical experiments: the strategic component would be linked to the PPC and the adaptive component to the cerebellum. In this model, the strategic component enters in conflict with the development and the generalisation of the adaptive aftereffects. This idea is compatible with the fact that a lesion of the PPC increases the transfer rate and the generalisation of the adaptation, as is also observed in unilateral neglect. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
32. Visual guidance based on optic flow: a biorobotic approach
- Author
-
Franceschini, Nicolas
- Subjects
- *
AFFERENT pathways , *NERVOUS system , *ROBOTICS , *EYE - Abstract
This paper addresses some basic questions as to how vision links up with action and serves to guide locomotion in both biological and artificial creatures. The thorough knowledge gained during the past five decades on insects'' sensory-motor abilities and the neuronal substrates involved has provided us with a rich source of inspiration for designing tomorrow''s self-guided vehicles and micro-vehicles, which will be able to cope with unforeseen events on the ground, under water, in the air, in space, on other planets, and inside the human body. Insects can teach us some useful tricks for designing agile autonomous robots. Since constructing a “biorobot” first requires exactly formulating the biological principles presumably involved, it gives us a unique opportunity of checking the soundness and robustness of these principles by bringing them face to face with the real physical world. “Biorobotics” therefore goes one step beyond computer simulation. It leads to experimenting with real physical robots which have to pass the stringent test of the real world. Biorobotics provide us with a new tool, which can help neurobiologists and neuroethologists to identify and investigate worthwhile issues in the field of sensory-motor control. Here we describe some of the visually guided terrestrial and aerial robots we have developed since 1985 on the basis of our biological findings. All these robots behave in response to the optic flow, i.e., they work by measuring the slip speed of the retinal image. Optic flow is sensed on-board by miniature electro-optical velocity sensors. The very principle of these sensors was based on studies in which we recorded the responses of single identified neurons to single photoreceptor stimulation in a model visual system: the fly''s compound eye. [Copyright &y& Elsevier]
- Published
- 2004
- Full Text
- View/download PDF
33. Visuo-motor control of the ipsilateral hand: evidence from right brain-damaged patients
- Author
-
Farnè, A., Roy, A.C., Paulignan, Y., Rode, G., Rossetti, Y., Boisson, D., and Jeannerod, M.
- Subjects
- *
BRAIN damaged patients , *MOTOR ability - Abstract
We investigated the extent to which the right hemisphere is involved in the control of the ipsilateral hand by analysing the kinematics of right-hand prehension in right brain-damaged (RBD) patients. We required patients to grasp one of five possible objects, equally-sized and distributed over a 40° wide workspace. With the purpose of investigating the right hemisphere contribution to the on-line visuo-motor control, we also assessed patients’ ability to correct their movement “in-flight”, in response to a sudden change of object position. Patients’ performance was compared to that of aged-matched controls. A Younger group of healthy subjects, matching the population classically tested on double-step paradigms, was also evaluated to fully assess whether patients’ kinematics could be partially due to normal ageing. As a further aim, the possible influence of hemispatial neglect was evaluated by comparing the performances of right brain-damaged patients with and without neglect. In normal subjects, the results confirmed and extended the notion of (a) positional tuning of grip formation, and (b) fast reactions following a change in object position. In addition, subtle effects of ageing on visuo-motor behaviour were shown by less efficient movement correction in the Elderly group. Patients executing reach-to-grasp actions into the left contralesional hemispace were selectively affected in both temporal and spatial aspects of movements. While their performances were relatively well preserved in the right hemispace, patients did not show positional tuning of grip formation, nor fast corrections of their movements when acting in the left hemispace. Interestingly, similar deficits were found irrespective of the presence of neglect. These results show that the right hemisphere contributes to the processing of visuo-motor information that is necessary for executing actions with the ipsilateral hand in the contralateral space. [Copyright &y& Elsevier]
- Published
- 2003
34. The influence of computer experience on visuo-motor control: implications for visuo-motor testing in Parkinson’s disease
- Author
-
Stoffers, D., Berendse, H.W., Deijen, J.B., and Wolters, E.Ch.
- Subjects
- *
COMPUTERS , *PARKINSON'S disease , *MOTOR ability - Abstract
Abnormalities in visuo-motor control have repeatedly been reported in Parkinson’s disease (PD) patients. In the more recent studies, tasks measuring visuo-motor performance are usually computerised tasks requiring the use of a mouse-like manipulandum. In healthy subjects, previous computer mouse experience can influence performance in computerised visuo-motor tasks. We, therefore, investigated the potential confounding effect of mouse experience in a visuo-motor task used in PD patients, the visuo-motor testing (VMT) system, and its concurrent usefulness in the diagnosis of PD.Our study population included 49 early PD patients and 31 controls. The VMT system involves moving a pointer over a sinusoidal path displayed on a computer screen by moving an unseen digitiser mouse over a tablet.In both PD patients and controls, subjects with low mouse experience scored worse than subjects with high mouse experience on variables measuring movement accuracy, direction and speed. After correction for mouse experience the aforementioned deficits were still present in PD patients with low mouse experience. However, PD patients with high mouse experience only showed deficits in movement accuracy. It would seem that previous mouse experience can at least partly compensate for deficits in directional control and speed in PD patients, implying a possible role for training in the treatment of functional motor impairments in PD.Future studies using computerised psychomotor tasks should take sufficient precautions to avoid potential confounding effects of mouse experience. The present data further suggest that only accuracy of visuo-motor control might be a useful parameter in the (early) diagnosis of PD. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
35. Optic flow and scene structure do not always contribute to the control of human walking
- Author
-
Harris, Julie M. and Bonas, William
- Subjects
- *
OPTICS , *PRISMS , *MOTION perception (Vision) - Abstract
Using displacing prisms to dissociate the influence of optic flow and egocentric direction, previous research (Current Biology 8 (1998) 1191) showed that people primarily use egocentric direction to control their locomotion on foot, rather than optic flow. When wearing displacing prisms, participants followed the curved path predicted by the use of simple egocentric direction, rather than a straight path, as predicted by the use of optic flow. It has previously been suggested that, in rich visual environments, other visual information including optic flow and static scene structure may influence locomotion in addition to direction. Here we report a study where neither scene structure nor optic flow have any influence on the control of walking. Participants wearing displacing prisms walked along a well-lit corridor (containing rich scene structure and flow) and along the same corridor in darkness (no scene structure or flow). Heading errors were not significantly different between the dark and light conditions. Thus, even under conditions of rich scene structure and high flow when walking in a well-lit corridor, participants follow the same curved paths as when these cues are not available. These results demonstrate that there are conditions under which visual direction is the only useful source of visual information for the control of locomotion. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
36. The role of short-term visuo-spatial memory in control of rapid multi-joint prehensive movements.
- Author
-
Kohler, J., Isenberg, C., Schönle, P., Inbar, G., and Conrad, B.
- Abstract
How memorized visuo-spatial information influences motor control and whether this information is able to replace the feedback processing in cases of visual deprivation was studied using an unrestrained finger- and hand-movement paradigm. Nineteen right-handed subjects were asked to grasp and lift a small block with the index finger and thumb of the right hand, as quickly as possible. The efficiency of motor performance was analysed by measuring the grasping time derived from tangential velocity profiles of the fingertips. The data revealed significantly shorter grasping times under continuous visual guidance than during blind grasping. Grasping times increased under conditions with stepwise prolongation of visual deprivation time prior to the movement onset. The results support the general concept that within the first seconds of visual deprivation, stored visuo-spatial information can partly compensate for the lack of continuous visual feedback. [ABSTRACT FROM AUTHOR]
- Published
- 1989
- Full Text
- View/download PDF
37. Evidence of a limited visuo-motor memory used in programming wrist movements.
- Author
-
Miall, R., Haggard, P., and Cole, J.
- Abstract
Human subjects can pre-program movements on the basis of visual cues. Experience in a particular task leads to the storage of appropriate control parameters which are used in programming subsequent movements, via a short-term motor memory. The form, duration and usage of this memory are, however, uncertain. Repetitive wrist flexion and extension movements were measured in four subjects. Three were neurologically normal men; the fourth subject had a peripheral large-fibre sensory neuropathy, depriving him of proprioceptive information about wrist movement. Subjects made alternating 45° wrist movements between two visual targets; visual feedback of wrist position was provided for the first part of each trial. After 10 s of tracking, the subjects paused for an interval of 0-24 s before resuming tracking without visual feedback of wrist position. The positional accuracy of subsequent movements was analysed with respect to pause interval. Movement accuracy was reduced by the removal of visual feedback in all four subjects: movements after the pause interval were less accurate than those before the pause. Errors also accumulated within each sequence of movements made without visual feedback. Analysis of the first movement in each trial after the pause indicated a clear relationship between movement accuracy and pause interval. In all four subjects, movement accuracy decayed with longer pause intervals. In the deafferented subject, manipulation of the visual inputs (requiring visual fixation, rather than normal pursuit of the target; or direct viewing of the hand instead of viewing a cursor on a computer screen) affected the relationship between pause interval and subsequent movement accuracy. We propose that the memory used when producing these movements is a short-lasting visuo-motor signal, lasting a few seconds, which is derived from visual knowledge of previous movements, rather than a memory of a particular motor output. This visuo-motor signal is used to scale the amplitude of subsequent wrist movements. The brevity of the visuo-motor memory and the resultant inaccuracy of this deafferented subject and of our neurologically normal subjects implies that human feedforward control of the amplitude and position of wrist movements is severely limited. [ABSTRACT FROM AUTHOR]
- Published
- 1995
- Full Text
- View/download PDF
38. Effects of tianeptine on the performance of a reaching movement in the cat.
- Author
-
Carayan, R., Mocaër, E., and Fabre-Thorpe, M.
- Abstract
Unlike other antidepressant drugs, tianeptine, when administered to cats at doses ranging from 1.2 to 5 mg/kg, produces an increase in arousal associated with longer sequences of immobile attentiveness. The present study analyses tianeptine-induced effects on visuomotor performance. Cats were trained to perform a pointing movement towards a randomly moving spot of light. Following tianeptine treatment (5 mg/kg), visuomotor performance was totally disrupted. When 2.5 mg/kg tianeptine was used, the accuracy of performance was unaffected, whereas the latency of movement onset was considerably and consistently increased. On a number of occasions the movement took also longer to perform. Following lower doses (0.6-1.2 mg/kg), performance was rarely impaired; in contrast, an improvement of visuo-motor scores was observed. This improvement was mostly characterized by an increased accuracy and could be associated with shorter latencies of movement onset or shorter movement times. Desipramine, another antidepressant drug having few sedative effects, induced a clear delay of movement onset when first administered. Further injections did not produce any changes in the visuo-motor performance. These results are discussed in relation with other effects of tianeptine, in particular its facilitatory effect on attentional processes. [ABSTRACT FROM AUTHOR]
- Published
- 1991
- Full Text
- View/download PDF
39. A margin for error in grasping: hand pre-shaping takes into account task-dependent changes in the probability of errors
- Author
-
Simon J. Watt, Pierre-Arthur Suray, and Bruce Keefe
- Subjects
Adult ,Male ,Grasping ,Adolescent ,Computer science ,Grip aperture ,Margin of error ,Visual feedback ,Motor Activity ,050105 experimental psychology ,Task (project management) ,Probability of success ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Humans ,0501 psychology and cognitive sciences ,Margin for error ,Movement (music) ,General Neuroscience ,05 social sciences ,Work (physics) ,Uncertainty ,Visual uncertainty ,Term (time) ,Blurring vision ,Visual Perception ,Female ,Visuo-motor control ,030217 neurology & neurosurgery ,Psychomotor Performance ,Cognitive psychology ,Research Article - Abstract
Ideal grasping movements should maintain an appropriate probability of success, while controlling movement-related costs, in the presence of varying visual (and motor) uncertainty. It is often assumed that the probability of errors is managed by adjusting a margin for error in hand opening (e.g., opening the hand wider with increased visual uncertainty). This idea is intuitive, but non-trivial. It implies not only that the brain can estimate the amount of uncertainty, but also that it can compute how different possible alterations to the movement will affect the probability of errors—which we term the ‘probability landscape’. Previous work suggests the amount of uncertainty is factored into grasping movements. Our aim was to determine whether grasping movements are also sensitive to the probability landscape. Subjects completed three different grasping tasks, with naturally different probability landscapes, such that appropriate margin-for-error responses to increased uncertainty were qualitatively different (opening the hand wider, the same amount, or less wide). We increased visual uncertainty by blurring vision, and by covering one eye. Movements were performed without visual feedback to isolate uncertainty in the brain’s initial estimate of object properties. Changes to hand opening in response to increased visual uncertainty closely resembled those predicted by the margin-for-error account, suggesting that grasping is sensitive to the probability landscape associated with different tasks. Our findings therefore support the intuitive idea that grasping movements employ a true margin-for-error mechanism, which exerts active control over the probability of errors across changing circumstances.
- Published
- 2018
40. Motion parallax via head movements modulates visuo-motor control in pigeons.
- Author
-
Hataji Y, Kuroshima H, and Fujita K
- Subjects
- Animals, Columbidae, Cues, Depth Perception, Motion, Visual Perception, Head Movements, Motion Perception
- Abstract
Although it has been proposed that birds acquire visual depth cues through dynamic head movements, behavioral evidence on how birds use motion parallax depth cues caused by self-motion is lacking. This study investigated whether self-generated motion parallax modulates pecking motor control and visual size perception in pigeons ( Columba livia ). We trained pigeons to peck a target on a touch monitor and to classify it as small or large. To manipulate motion parallax of the target, we changed the target position on the monitor according to the bird's head position in real time using a custom-built head tracker with two cameras. Pecking motor control was affected by the manipulation of motion parallax: when the motion parallax signified the target position farther than the monitor surface, the head position just before pecking to target was near the monitor surface, and vice versa. By contrast, motion parallax did not affect how the pigeons classified target sizes, implying that motion parallax might not contribute to size constancy in pigeons. These results indicate that motion parallax via head movements modulates pecking motor control in pigeons, suggesting that head movements of pigeons have the visual function of accessing motion parallax depth cues., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)
- Published
- 2021
- Full Text
- View/download PDF
41. The Pointing Errors in Optic Ataxia Reveal the Role of 'Peripheral Magnification' of the PPC
- Author
-
Hisaaki Ota, Laure Pisella, Karen T. Reilly, Yves Rossetti, Philippe Vindras, Annabelle Blangero, Espace et Action, Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-IFR19-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
posterior parietal cortex ,visuo-motor control ,genetic structures ,Cognitive Neuroscience ,Visual space ,[SDV]Life Sciences [q-bio] ,Magnification ,Posterior parietal cortex ,optic ataxia ,lcsh:RC346-429 ,050105 experimental psychology ,lcsh:RC321-571 ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,models ,0302 clinical medicine ,Visual Objects ,Motor system ,peripheral vision ,0501 psychology and cognitive sciences ,Computer vision ,theoretical ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,visual central magnification ,lcsh:Neurology. Diseases of the nervous system ,ComputingMilieux_MISCELLANEOUS ,computer.programming_language ,Original Research ,business.industry ,05 social sciences ,Neuropsychology ,mathematical modeling ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Models, Theoretical ,Sensory Systems ,Visual field ,Peripheral vision ,[SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,Artificial intelligence ,Psychology ,business ,computer ,030217 neurology & neurosurgery ,Neuroscience - Abstract
Interaction with visual objects in the environment requires an accurate correspondence between visual space and its internal representation within the brain. Many clinical conditions involve some impairment in visuo-motor control and the errors created by the lesion of a specific brain region are neither random nor uninformative. Modern approaches to studying the neuropsychology of action require powerful data-driven analyses and error modelling in order to understand the function of the lesioned areas. In the present paper we carried out mixed-effect analyses of the pointing errors of seven optic ataxia patients and seven control subjects. We found that a small parameter set is sufficient to explain the pointing errors produced by unilateral optic ataxia patients. In particular, the extremely stereotypical errors made when pointing toward the contralesional visual field can be fitted by mathematical models similar to those used to model central magnification in cortical or sub-cortical structure(s). Our interpretation is that visual areas that contain this footprint of central magnification guide pointing movements when the posterior parietal cortex is damaged and that the functional role of the posterior parietal cortex is to actively compensate for the under-representation of peripheral vision that accompanies central magnification. Optic ataxia misreaching reveals what would be hand movement accuracy and precision if the human motor system did not include elaborated corrective processes for reaching and grasping to non-foveated targets.
- Published
- 2016
42. Grasping objects by former amputees: The visuo-motor control of allografted hands
- Author
-
Lionel Badet, Livio Finos, Gilles Rode, Aram Gazarian, Patrice Revol, L. Huchon, Yves Rossetti, Alice C. Roy, Emmanuel Morelon, Laurence Bernardon, and Alessandro Farnè
- Subjects
Adult ,Male ,medicine.medical_specialty ,visuo-motor control ,medicine.medical_treatment ,Motor program ,030230 surgery ,Motor Activity ,Hand transplantation ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Physical medicine and rehabilitation ,Amputees ,Developmental Neuroscience ,Functional neuroimaging ,Feedback, Sensory ,medicine ,Humans ,prehension ,Neuronal Plasticity ,Proprioception ,Medicine (all) ,kinematics ,neural plasticity ,Neurology ,Neurology (clinical) ,Motor control ,Middle Aged ,Biomechanical Phenomena ,Transplantation ,medicine.anatomical_structure ,Amputation ,Upper limb ,Female ,Psychology ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Purpose Hand allograft has recently emerged as a therapeutic option for upper limb amputees. Functional neuroimaging studies have progressively revealed sensorimotor cortices plasticity following both amputation and transplantation. The purpose of our study was to assess and characterize the functional recovery of the visuo-motor control of prehension in bilateral hand transplanted patients. Methods Using kinematics recordings, we characterized the performance of prehension with or without visual feed-back for object of different position and size, in five bilateral hand allograft recipients and age-matched control subjects. Both hands were assessed, separately. Results Despite an overall slower execution, allografted patients succeeded in grasping for more than 90% of the trials. They exhibited a preserved hand grip scaling according to object size, and preserved prehension performances when tested without visual feedback. These findings highlight the allograft recipients' abilities to produce an effective motor program, and a good proprioceptive-dependent online control. Nevertheless, the maximum grip aperture was reduced and delayed, the coupling between Transport and Grasp components was altered, and the final phase of the movement was lengthened. Conclusion Hand allotransplantation can offer recipients a good recovery of the visuo-motor control of prehension, with slight impairments likely attributable to peripheral neuro-orthopedic limitations.
- Published
- 2016
43. On the mechanisms underlying Prism Adaptation: A review of neuro-imaging and neuro-stimulation studies.
- Author
-
Panico F, Rossetti Y, and Trojano L
- Subjects
- Cerebellum, Cognition, Functional Laterality, Humans, Space Perception, Adaptation, Physiological, Brain diagnostic imaging, Perceptual Disorders
- Abstract
Prism Adaptation (PA) is a behavioral task to assess visuo-motor plasticity and to ameliorate the symptoms of unilateral spatial neglect. Several studies have addressed the effects of PA on both sensory-motor and cognitive processing and the contribution of different brain regions to PA, although via non standardized procedures. The aim of the present review is to gather findings from the neuro-imaging and neuro-stimulation fields and put forward an interpretative framework for PA. The available evidence supports that sensory-motor effects of PA would mainly relate to the activation of a cerebello-parietal network, while the effects on spatial cognition would be mediated by bottom-up activation of temporal and prefrontal regions. The consolidation of PA effects would rely on activity of the motor cortex. The use of standardized PA procedures is strongly recommended for a systematic and accurate investigation of the neural mechanisms of PA., Competing Interests: Declaration of Competing Interest None., (Copyright © 2019 Elsevier Ltd. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
44. Dissociation of extrastriate body and biological-motion selective areas by manipulation of visual-motor congruency
- Author
-
Ioannis Kontaris, Alison J. Wiggett, and Paul E. Downing
- Subjects
Adult ,Male ,Visual perception ,genetic structures ,Action perception ,Cognitive Neuroscience ,Experimental and Cognitive Psychology ,Neuropsychological Tests ,Functional Laterality ,Article ,050105 experimental psychology ,Extrastriate body area ,Judgment ,Motion ,Young Adult ,03 medical and health sciences ,Behavioral Neuroscience ,0302 clinical medicine ,Extrastriate cortex ,Image Processing, Computer-Assisted ,Reaction Time ,medicine ,Humans ,Visual Pathways ,0501 psychology and cognitive sciences ,Brain Mapping ,fMRI ,05 social sciences ,Motor control ,Body movement ,Superior temporal sulcus ,Biological motion ,Magnetic Resonance Imaging ,Corpus Striatum ,Oxygen ,Fusiform body area ,Visual cortex ,medicine.anatomical_structure ,Visual Perception ,Female ,Psychology ,Visuo-motor control ,Neuroscience ,Photic Stimulation ,Psychomotor Performance ,030217 neurology & neurosurgery - Abstract
To date, several posterior brain regions have been identified that play a role in the visual perception of other people and their movements. The aim of the present study is to understand how these areas may be involved in relating body movements to their visual consequences. We used fMRI to examine the extrastriate body area (EBA), the fusiform body area (FBA), and an area in the posterior superior temporal sulcus (pSTS) that responds to patterns of human biological motion. Each area was localized in individual participants with independent scans. In the main experiment, participants performed and/or viewed simple, intransitive hand actions while in the scanner. An MR-compatible camera with a near-egocentric view of the participant's hand was used to manipulate the relationship between motor output and the visual stimulus. Participants’ only view of their hands was via this camera. In the Compatible condition, participants viewed their own live hand movements projected onto the screen. In the Incompatible condition, participants viewed actions that were different from the actions they were executing. In pSTS, the BOLD response in the Incompatible condition was significantly higher than in the Compatible condition. Further, the response in the Compatible condition was below baseline, and no greater than that found in a control condition in which hand actions were performed without any visual input. This indicates a strong suppression in pSTS of the response to the visual stimulus that arises from one's own actions. In contrast, in EBA and FBA, we found a large but equivalent response to the Compatible and Incompatible conditions, and this response was the same as that elicited in a control condition in which hand actions were viewed passively, with no concurrent motor task. These findings indicate that, in contrast to pSTS, EBA and FBA are decoupled from motor systems. Instead we propose that their role is limited to perceptual analysis of body-related visual input.
- Published
- 2009
- Full Text
- View/download PDF
45. Visual and musculoskeletal underpinnings of anchoring in rhythmic visuo-motor tracking
- Author
-
Peter J. Beek, Melvyn Roerdink, Ellen D. Ophoff, C. (Lieke) E. Peper, Movement Behavior, and Research Institute MOVE
- Subjects
Male ,Wrist Joint ,Periodicity ,Eye Movements ,genetic structures ,Wrist position ,Kinematics ,Wrist ,Neuropsychological Tests ,0302 clinical medicine ,Eye–hand coordination ,General Neuroscience ,05 social sciences ,Visual information ,Middle Aged ,medicine.anatomical_structure ,Female ,Movement trajectories ,Psychology ,Research Article ,Adult ,medicine.medical_specialty ,Neuroscience(all) ,Posture ,Anchoring ,Coordination dynamics ,Fixation, Ocular ,050105 experimental psychology ,Feedback ,03 medical and health sciences ,Physical medicine and rehabilitation ,Biological Clocks ,Orientation ,medicine ,Humans ,0501 psychology and cognitive sciences ,Muscle, Skeletal ,Communication ,business.industry ,Eye movement ,Motor control ,Manual tracking ,Proprioception ,Gaze ,Oculomotor Muscles ,Space Perception ,Fixation (visual) ,business ,Visuo-motor control ,030217 neurology & neurosurgery ,Photic Stimulation ,Psychomotor Performance - Abstract
Anchoring, that is, a local reduction in kinematic (i.e., spatio-temporal) variability, is commonly observed in cyclical movements, often at or around reversal points. Two kinds of underpinnings of anchoring have been identified - visual and musculoskeletal - yet their relative contributions and interrelations are largely unknown. We conducted an experiment to delineate the effects of visual and musculoskeletal factors on anchoring behavior in visuo-motor tracking. Thirteen participants (reduced to 12 in the analyses) tracked a sinusoidally moving visual target signal by making flexion-extension movements about the wrist, while both visual (i.e., gaze direction) and musculoskeletal (i.e., wrist posture) factors were manipulated in a fully crossed (3 x 3) design. Anchoring was affected by both factors in the absence of any significant interactions, implying that their contributions were independent. When gaze was directed to one of the target turning points, spatial endpoint variability at this point was reduced, but not temporal endpoint variability. With the wrist in a flexed posture, spatial and temporal endpoint variability were both smaller for the flexion endpoint than for the extension endpoint, while the converse was true for tracking with the wrist extended. Differential anchoring effects were absent for a neutral wrist posture and when gaze was fixated in between the two target turning points. Detailed analyses of the tracking trajectories in terms of velocity profiles and Hooke's portraits showed that the tracking dynamics were affected more by wrist posture than by gaze direction. The discussion focuses on the processes underlying the observed independent effects of gaze direction and wrist posture on anchoring as well as their implications for the notion of anchoring as a generic feature of sensorimotor coordination. © 2007 Springer-Verlag.
- Published
- 2008
46. Optic flow and scene structure do not always contribute to the control of human walking
- Author
-
William Bonas and Julie M. Harris
- Subjects
Heading (navigation) ,Straight path ,Computer science ,media_common.quotation_subject ,Optical flow ,Motion perception ,Walking ,Perception ,Psychophysics ,Humans ,Computer vision ,Control (linguistics) ,media_common ,Communication ,business.industry ,Optic flow ,Sensory Systems ,Ophthalmology ,Flow (mathematics) ,Visual Perception ,Artificial intelligence ,Cues ,High flow ,business ,Egocentric direction ,Visuo-motor control ,Locomotion ,Psychomotor Performance - Abstract
Using displacing prisms to dissociate the influence of optic flow and egocentric direction, previous research (Current Biology 8 (1998) 1191) showed that people primarily use egocentric direction to control their locomotion on foot, rather than optic flow. When wearing displacing prisms, participants followed the curved path predicted by the use of simple egocentric direction, rather than a straight path, as predicted by the use of optic flow. It has previously been suggested that, in rich visual environments, other visual information including optic flow and static scene structure may influence locomotion in addition to direction. Here we report a study where neither scene structure nor optic flow have any influence on the control of walking. Participants wearing displacing prisms walked along a well-lit corridor (containing rich scene structure and flow) and along the same corridor in darkness (no scene structure or flow). Heading errors were not significantly different between the dark and light conditions. Thus, even under conditions of rich scene structure and high flow when walking in a well-lit corridor, participants follow the same curved paths as when these cues are not available. These results demonstrate that there are conditions under which visual direction is the only useful source of visual information for the control of locomotion.
- Published
- 2002
47. Compression of motor space expands perceptual spaces
- Author
-
R. Volcic, C. Fantoni, C. Caudek, F. Domini, Vision Science Society, Volcic, R., Fantoni, Carlo, Caudek, C., and Domini, F.
- Subjects
Ophthalmology ,Depth Perception ,Plasticity ,Visuo-Motor control ,Perception & Action ,Reaching & Grasping ,Sensory Systems - Published
- 2012
48. Insect inspired autopilots
- Author
-
Nicolas Franceschini, Franck Ruffier, Julien Serres, Serres, Julien R, Institut des Sciences du Mouvement Etienne Jules Marey (ISM), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
0303 health sciences ,Engineering ,Micro-air vehicles (MAV) ,business.industry ,Visually guided ,Feedback control ,[SCCO.NEUR]Cognitive science/Neuroscience ,Flow regulator ,[SCCO.NEUR] Cognitive science/Neuroscience ,Control engineering ,Compound eye ,Avionics ,[SPI.AUTO]Engineering Sciences [physics]/Automatic ,03 medical and health sciences ,0302 clinical medicine ,[SPI.AUTO] Engineering Sciences [physics]/Automatic ,Obstacle avoidance ,optic flow ,Robot ,Underwater ,business ,Visuo-motor control ,Insect ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
This paper deals with the control problems involved in insects' and robots' visually guided piloting. Explicit control schemes are presented which may explain how insects navigate by relying on optic flow cues, without requiring any distance or speed measurements. The concept of the optic flow regulator, a feedback control system based on OF sensors, is presented. We tested our control schemes in simulation, and implemented them on-board two types of miniature aerial robots, a helicopter and a hovercraft. Their electronic OF sensors were inspired by the results of our microelectrode studies on motion sensitive neurons in the housefly's compound eye. The control schemes described do without any conventional avionic sensors like rangefinders or speedometers, and therefore show great potential for safe autonomous control of aerial, underwater and space vehicles in unchartered environments.
- Published
- 2009
49. Internal models and prediction of visual gravitational motion
- Author
-
Patrice Senot, Francesco Lacquaniti, Myrka Zago, and Joseph McIntyre
- Subjects
media_common.quotation_subject ,Models, Neurological ,Motion Perception ,occam ,Models, Psychological ,Internal models ,Settore BIO/09 ,Motion (physics) ,Compensation (engineering) ,Gravitation ,Perception ,Motion perception ,Timing ,Visuo-motor control ,Psychophysics ,Humans ,Gravity Sensing ,computer.programming_language ,media_common ,Communication ,business.industry ,Object (philosophy) ,Sensory Systems ,Action (physics) ,Ophthalmology ,business ,Psychology ,computer ,Algorithm ,Psychomotor Performance - Abstract
Baurès et al. [Baurès, R., Benguigui, N., Amorim, M.-A., & Siegler, I. A. (2007). Intercepting free falling objects: Better use Occam’s razor than internalize Newton’s law. Vision Research, 47, 2982–2991] rejected the hypothesis that free-falling objects are intercepted using a predictive model of gravity. They argued instead for “a continuous guide for action timing” based on visual information updated till target capture. Here we show that their arguments are flawed, because they fail to consider the impact of sensori-motor delays on interception behaviour and the need for neural compensation of such delays. When intercepting a free-falling object, the delays can be overcome by a predictive model of the effects of gravity on target motion.
- Published
- 2008
50. Vision based autopilot in flies
- Author
-
Franceschini, Nicolas, Ruffier, Franck, Serres, Julien, Serres, Julien R, Institut des Sciences du Mouvement Etienne Jules Marey (ISM), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU), Janelia Farm Research Campus, Howard Hughes Medical Institute, and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
visuo-motor control ,[SPI.AUTO] Engineering Sciences [physics]/Automatic ,motion vision ,[SCCO.NEUR]Cognitive science/Neuroscience ,[SCCO.NEUR] Cognitive science/Neuroscience ,Elementary Motion Detector (EMD) ,Optic Flow (OF) ,visually-guided behavior ,Micro-Air Vehicles (MAV) ,[SPI.AUTO]Engineering Sciences [physics]/Automatic - Abstract
International audience; When insects are flying forwards, the image of the ground sweeps backwards across their ventral viewfield, forming an ‘optic flow’, which depends on both the ground speed and the height of flight. To explain how these animals manage to avoid the ground using this image motion cue, we suggest that insect navigation hinges on a visual feedback loop we have called the optic flow regulator, which controls the vertical lift. To test this idea, we built a micro-helicopter equipped with a fly-inspired optic flow sensor and an optic flow regulator. We showed that this fly-by-sight microrobot can perform exacting tasks such as take-off, level flight and landing. Our control scheme accounts for many hitherto unexplained findings published during the last 70 years on insects’ visually guided performances, including the fact that honeybees descend by headwind, land with a constant slope, and drown when travelling over mirror-smooth water Our control scheme explains how insects manage to fly safely without any of the instruments used onboard aircraft to measure the height of flight, the air speed, the ground speed and the descent speed. An optic flow regulator is quite simple in terms of its neural implementation and just as appropriate for insects as it would be for aircraft.
- Published
- 2007
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.