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Background/Hypothesis: Motion sensitivity symptoms, such as dizziness or unsteadiness, are frequently reported as non-headache symptoms of migraine. Postural imbalance has been observed in subjects with vestibular migraine, chronic migraine, and aura. We aimed to assess the ability of largest Lyapunov's exponent for a short time series (sLLE), which reflects the ability to cope with internal perturbations during gait, to detect differences in local dynamic stability between individuals with migraine without aura (MO) with an episodic pattern between attacks and healthy subjects (HS). Methods: Trunk accelerations of 47 MO and 38 HS were recorded during gait using an inertial measurement unit. The discriminative ability of sLLE was assessed through receiver-operating characteristics curves and cutoff analysis. Partial correlation analysis was conducted between the clinical and gait variables, excluding the effects of gait speed. Results: MO showed higher sLLE values, and reduced pelvic rotation, pelvic tilt, and stride length values. sLLEML and pelvic rotation showed good ability to discriminate between MO and HS and were correlated with the perceived pain, migraine disability assessment score, and each other. Conclusions: these findings may provide new insights into the postural balance control mechanism in subjects with MO and introduce the sLLEML as a potential measure of dynamic instability in MO. [ABSTRACT FROM AUTHOR]

• many neurons in the central nucleus of the inferior colliculus are sensitive to sweeps of interaural time difference in tones or broadband noise. • response to such sweeps can match the response to static stimuli but can also drastically differ. • the difference in response to dynamic versus static stimuli predominantly reflects a neuron's temporal response pattern. • a roughly equal number of neurons showed build-up and adapting patterns. Many neurons in the central nucleus of the inferior colliculus (IC) show sensitivity to interaural time differences (ITDs), which is thought to be relayed from the brainstem. However, studies with interaural phase modulation of pure tones showed that IC neurons have a sensitivity to changes in ITD that is not present at the level of the brainstem. This sensitivity has been interpreted as a form of sensitivity to motion. A new type of stimulus is used here to study the sensitivity of IC neurons to dynamic changes in ITD, in which broad- or narrowband stimuli are swept through a range of ITDs with arbitrary start-ITD, end-ITD, speed, and direction. Extracellular recordings were obtained under barbiturate anesthesia in the cat. We applied the same analyses as previously introduced for the study of responses to tones. We find effects of motion which are similar to those described in response to interaural phase modulation of tones. The size of the effects strongly depended on the motion parameters but was overall smaller than reported for tones. We found that the effects of motion could largely be explained by the temporal response pattern of the neuron such as adaptation and build-up. Our data add to previous evidence questioning true coding of motion at the level of the IC. [ABSTRACT FROM AUTHOR]

Background: Persistent postural-perceptual dizziness (PPPD) is the most common functional vestibular disorder. A multisensory mismatch altered by psychological influences is considered to be an important pathophysiological mechanism. Increased cortical and subcortical excitability may play a role in the pathophysiology of PPPD. We hypothesized that decreased motion perception thresholds reflect one mechanism of the abnormal vestibular responsiveness in this disorder. We investigated the vestibular perception thresholds and the vestibular ocular reflex with a rotatory chair experiment to gain insights in the processing and adaption to vestibular provocation.Methods: In this cross-sectional study 26 female PPPD patients and 33 healthy female age matched controls (HC) were investigated sitting in a motorized rotary chair shielded regarding visual and acoustic stimuli. The chair was rotated for 20 minutes with slowly increasing velocity to a maximum of 72°/s. We functionally tested motion perception thresholds and vegetative responses to rotation as well as vestibular-ocular reflex thresholds. We additionally investigated several psychological comorbidities (i.e. depression, anxiety, somatosensory amplification) using validated scores. Conventional dizziness scores were obtained to quantify the experienced dizziness and impact on daily life.Results: PPPD patients showed a significant reduced vestibulo-perceptual threshold (PPPD: 10.9°/s vs. HC: 29.5°/s; p<0.001) with increased motion sensitivity and concomitant vegetative response during and after the chair rotation compared to healthy controls. The extent of increased vestibular sensitivity was in correlation with the duration of the disease (p=0.043). No significant difference was measured regarding nystagmus parameters between both groups.Conclusion: PPPD patients showed increased vegetative response as well as decreased vestibulo-perceptual thresholds which are related to disease duration. This is of interest as PPPD might be sustained by increased vestibular excitability leading to motion intolerance and induction of dizziness when exposed to movement. [ABSTRACT FROM AUTHOR]

In primates, broad thorny retinal ganglion cells are highly sensitive to small, moving stimuli. They have tortuous, fine dendrites with many short, spine‐like branches that occupy three contiguous strata in the middle of the inner plexiform layer. The neural circuits that generate their responses to moving stimuli are not well‐understood, and that was the goal of this study. A connectome from central macaque retina was generated by serial block‐face scanning electron microscopy, a broad thorny cell was reconstructed, and its synaptic inputs were analyzed. It received fewer than 2% of its inputs from both ON and OFF types of bipolar cells; the vast majority of its inputs were from amacrine cells. The presynaptic amacrine cells were reconstructed, and seven types were identified based on their characteristic morphology. Two types of narrow‐field cells, knotty bistratified Type 1 and wavy multistratified Type 2, were identified. Two types of medium‐field amacrine cells, ON starburst and spiny, were also presynaptic to the broad thorny cell. Three types of wide‐field amacrine cells, wiry Type 2, stellate wavy, and semilunar Type 2, also made synapses onto the broad thorny cell. Physiological experiments using a macaque retinal preparation in vitro confirmed that broad thorny cells received robust excitatory input from both the ON and the OFF pathways. Given the paucity of bipolar cell inputs, it is likely that amacrine cells provided much of the excitatory input, in addition to inhibitory input. [ABSTRACT FROM AUTHOR]

Concussion can lead to various symptoms such as balance problems, memory impairments, dizziness, and/or headaches. It has been previously suggested that during self-motion relevant tasks, individuals with concussion may rely heavily on visual information to compensate for potentially less reliable vestibular inputs and/or problems with multisensory integration. As such, concussed individuals may also be more sensitive to other visually-driven sensations such as visually induced motion sickness (VIMS). To investigate whether concussed individuals are at elevated risk of experiencing VIMS, we exposed participants with concussion (n = 16) and healthy controls (n = 15) to a virtual scene depicting visual self-motion down a grocery store aisle at different speeds. Participants with concussion were further separated into symptomatic and asymptomatic groups. VIMS was measured with the SSQ before and after stimulus exposure, and visual dependence, self-reported dizziness, and somatization were recorded at baseline. Results showed that concussed participants who were symptomatic demonstrated significantly higher SSQ scores after stimulus presentation compared to healthy controls and those who were asymptomatic. Visual dependence was positively correlated with the level of VIMS in healthy controls and participants with concussion. Our results suggest that the presence of concussion symptoms at time of testing significantly increased the risk and severity of VIMS. This finding is of relevance with regards to the use of visual display devices such as Virtual Reality applications in the assessment and rehabilitation of individuals with concussion. [ABSTRACT FROM AUTHOR]

Background and purpose: Vestibular migraine (VM) patients are ictally and interictally hypersensitive for self‐motion and visual perception. Increased cortical excitability of the vestibular system represented by lowered motion perception thresholds might play an important role in the pathophysiology of VM. We aimed to compare motion perception thresholds and the vegetative response to rotatory motion, as well as the vestibulo‐ocular reflex (VOR) during rotation in VM patients compared to healthy controls (HC). Methods: In this cross‐sectional study, 28 female VM patients in the interictal state and 33 age‐ and gender‐matched HC were investigated sitting in a motorized rotary chair shielded regarding visual and acoustic stimuli for 20 min with slowly increasing velocity (maximum = 72°/s). The motion perception threshold was indicated by the participants by pushing a button. During and after rotation, participants rated the presence and extent of motion sickness using a sickness rating scale. Results: We detected lower motion perception thresholds (7.54°/s vs. 23.49°/s; p < 0.001) in VM patients compared to HC but no difference at the basic VOR thresholds. Furthermore, the patients showed enhanced susceptibility to motion sickness during and after the rotation. Conclusions: We provide evidence for decreased motion perception thresholds and pronounced susceptibility to motion sickness in VM patients in the interictal state, which could indicate alterations in higher levels of vestibular processing. Future studies should determine whether this could be the pathophysiological hallmark of VM either as a unique disease entity or in differentiation from other forms of migraine. [ABSTRACT FROM AUTHOR]

Stereoscopic video quality assessment has become a major research topic in recent years. Existing stereoscopic video quality metrics are predominantly based on stereoscopic image quality metrics extended to the time domain via for example temporal pooling. These approaches do not explicitly consider the motion sensitivity of the Human Visual System (HVS). To address this limitation, this paper introduces a novel HVS model inspired by physiological findings characterising the motion sensitive response of complex cells in the primary visual cortex (V1 area). The proposed HVS model generalises previous HVS models, which characterised the behaviour of simple and complex cells but ignored motion sensitivity, by estimating optical flow to measure scene velocity at different scales and orientations. The local motion characteristics (direction and amplitude) are used to modulate the output of complex cells. The model is applied to develop a new type of full-reference stereoscopic video quality metrics which uniquely combine non-motion sensitive and motion sensitive energy terms to mimic the response of the HVS. A tailored two-stage multi-variate stepwise regression algorithm is introduced to determine the optimal contribution of each energy term. The two proposed stereoscopic video quality metrics are evaluated on three stereoscopic video datasets. Results indicate that they achieve average correlations with subjective scores of 0.9257 (PLCC), 0.9338 and 0.9120 (SRCC), 0.8622 and 0.8306 (KRCC), and outperform previous stereoscopic video quality metrics including other recent HVS-based metrics. [ABSTRACT FROM AUTHOR]

Parasol cells are one of the major types of primate retinal ganglion cells. The goal of this study was to describe the synaptic inputs that shape the light responses of the ON type of parasol cells, which are excited by increments in light intensity. A connectome from central macaque retina was generated by serial blockface scanning electron microscopy. Six neighboring ON parasol cells were reconstructed, and their synaptic inputs were analyzed. On average, they received 21% of their input from bipolar cells, excitatory local circuit neurons receiving input from cones. The majority of their input was from amacrine cells, local circuit neurons of the inner retina that are typically inhibitory. Their contributions to the neural circuit providing input to parasol cells are not well‐understood, and the focus of this study was on the presynaptic wide‐field amacrine cells, which provided 17% of the input to ON parasol cells. These are GABAergic amacrine cells with long, relatively straight dendrites, and sometimes also axons, that run in a single, narrow stratum of the inner plexiform layer. The presynaptic wide‐field amacrine cells were reconstructed, and two types were identified based on their characteristic morphology. One presynaptic amacrine cell was identified as semilunar type 2, a polyaxonal cell that is electrically coupled to ON parasol cells. A second amacrine was identified as wiry type 2, a type known to be sensitive to motion. These inputs likely make ON parasol cells more sensitive to stimuli that are rapidly changing outside their classical receptive fields. [ABSTRACT FROM AUTHOR]

Some people doubt that the concept of developmental dyslexia (DD) is useful at all because the phonological weaknesses seen in DD cannot be distinguished from those found in every person with poor reading skills, whatever their cause. Here I argue that true DD is characterised by poor temporal processing, hence impaired visual and auditory sequencing, that is caused by impaired development of transient/magnocellular (M-) systems throughout the brain. These deficits can be measured in order to distinguish the causes of the phonological weaknesses in DD from those causing similar deficits in other types of poor reading. Importantly this knowledge can be exploited to develop effective improvements in treatment. The evidence for impaired visual magnocellular function in many, if not all, people with dyslexia is now overwhelming; it is supported not only by psychophysical tests of M- function, but also by electrophysiological, eye movement, attentional, imaging, interventional and genetic findings. Analogously, auditory temporal processing is mediated by auditory transient, 'magnocellular', processing systems, and evidence is accumulating persuasively that this system is also impaired in dyslexics. I briefly introduce the idea that 'motor magnocellular systems' may also be impaired in dyslexia, then consider genetic, immunological and nutritional factors that interact to cause the impaired magnocellular phenotype. I then discuss why the dyslexic phenotype is so common by speculating about what strengths it might confer that would maintain the responsible genes in the human genome. • The phonological deficit in developmental dyslexia is due to poor visual sequencing of the letters and poor auditory sequencing of the letter sounds in words. • These deficiencies result from impaired development of CNS timing systems which are mediated by large 'magnocellular' neurones throughout the brain. • The evidence is now overwhelming that people with dyslexia have impaired development of magnocellular neurons. • This abnormality has a genetic, immunological and nutritional basis. • This new understanding is enabling greatly improved diagnosis and remediation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chronic motion sensitivity (CMS) has been defined as a feeling of un-wellness elicited by either actual or perceived motion. CMS is a common condition and is more prevalent in females than in males. In addition to a variety of symptoms, young adults with CMS have less postural stability than those without CMS. OBJECTIVE: To determine whether dependence on visual cues for postural stability is different between young adults with and without CMS, and whether it differs by gender within each group. METHODS: Sixty young adults (30 females and 30 males) were assigned to one of two groups (CMS or non-CMS) using the Motion Sickness Susceptibility Questionnaire-Short Form. Postural stability was measured for all participants using the Bertec Balance Advantage-Computerized Dynamic Posturography with Immersion Virtual Reality. RESULTS: A significant difference was found in mean postural stability scores during immersion virtual reality between the CMS and non-CMS groups (p < 0.001); however, no significant difference was shown in mean postural stability between males and females within the CMS and non-CMS groups (p = 0.10 and p = 0.97, respectively). CONCLUSION: The results suggest that young adults with CMS are over-reliant on visual cues for postural stability, and that visual dependence is not influenced by gender. [ABSTRACT FROM AUTHOR]

Identifying perceptual thresholds is critical for understanding the mechanisms that underlie signal evolution. Using computer-animated stimuli, we examined visual speed sensitivity in the Jacky dragon Amphibolurus muricatus, a species that makes extensive use of rapid motor patterns in social communication. First, focal lizards were tested in discrimination trials using random-dot kinematograms displaying combinations of speed, coherence, and direction. Second, we measured subject lizards' ability to predict the appearance of a secondary reinforcer (1 of 3 different computer-generated animations of invertebrates: cricket, spider, and mite) based on the direction of movement of a field of drifting dots by following a set of behavioural responses (e.g., orienting response, latency to respond) to our virtual stimuli. We found an effect of both speed and coherence, as well as an interaction between these 2 factors on the perception of moving stimuli. Overall, our results showed that Jacky dragons have acute sensitivity to high speeds. We then employed an optic flow analysis to match the performance to ecologically relevant motion. Our results suggest that the Jacky dragon visual system may have been shaped to detect fast motion. This pre-existing sensitivity may have constrained the evolution of conspecific displays. In contrast, Jacky dragons may have difficulty in detecting the movement of ambush predators, such as snakes and of some invertebrate prey. Our study also demonstrates the potential of the computeranimated stimuli technique for conducting nonintrusive tests to explore motion range and sensitivity in a visually mediated species. [ABSTRACT FROM AUTHOR]

Background: In order to maintain balance, input from the vestibular, somatosensory, and visual systems must work together to allow the patient to perform comfortably and to exist in his or her world. Any imbalance leads to a multitude of symptoms, including vertigo or disequilibrium. This paper analyzes a case of a patient suffering from long-standing vertigo and self-reported debilitating visual dysfunction. Case Report: A 47-year-old female presented with complaints of long-standing dizziness, a feeling of sickness in busy areas like grocery stores, the inability to multitask (including the inability to walk and talk at the same time comfortably), motion sensitivity, and disorientation. Due to her symptoms, the patient was unable to work, drive, or interact in social situations. Visual analysis revealed convergence insufficiency, oculomotor dysfunction, visual-vestibular sensory mismatch, and anomalous spatial perception. Traumatic brain injury testing quantified the patient's complaints. Completion of a vision therapy program, with an emphasis on dynamic techniques including procedures to rehabilitate accommodative, vergence, and oculomotor insufficiencies, allowed the patient to return to her activities of daily living. Conclusion: In order to assist in the rehabilitative process, optometrists and other medical professionals must be cognizant of the vital role the visual system plays in regulating balance. Vision therapy must be considered as a treatment option to allow the rehabilitation process to be effective. [ABSTRACT FROM AUTHOR]

Purpose To quantify the effects of driver age on night-time pedestrian conspicuity, and to determine whether individual differences in visual performance can predict drivers' ability to recognise pedestrians at night. Methods Participants were 32 visually normal drivers (20 younger: M = 24.4 years ± 6.4 years; 12 older: M = 72.0 years ± 5.0 years). Visual performance was measured in a laboratory-based testing session including visual acuity, contrast sensitivity, motion sensitivity and the useful field of view. Night-time pedestrian recognition distances were recorded while participants drove an instrumented vehicle along a closed road course at night; to increase the workload of drivers, auditory and visual distracter tasks were presented for some of the laps. Pedestrians walked in place, sideways to the oncoming vehicles, and wore either a standard high visibility reflective vest or reflective tape positioned on the movable joints (biological motion). Results Driver age and pedestrian clothing significantly ( p < 0.05) affected the distance at which the drivers first responded to the pedestrians. Older drivers recognised pedestrians at approximately half the distance of the younger drivers and pedestrians were recognised more often and at longer distances when they wore a biological motion reflective clothing configuration than when they wore a reflective vest. Motion sensitivity was an independent predictor of pedestrian recognition distance, even when controlling for driver age. Conclusions The night-time pedestrian recognition capacity of older drivers was significantly worse than that of younger drivers. The distance at which drivers first recognised pedestrians at night was best predicted by a test of motion sensitivity. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether the Wu-Jones Motion Sensitivity Screening Test (MSST) accurately reflects the burden of optic nerve disease in several onchoendemic communities in Africa. Materials and Methods: The MSST was used to evaluate subjects in the communities of Raja in Sudan, Bushenyi in Uganda, Morogoro in Tanzania, and Ikon, Olomboro, and Gembu in Nigeria. Motion sensitivity was expressed as a percentage of motion detected in the individual eye, and this was averaged for the community. A perfectly normal eye would detect all motion and score 100%. Results: In this study, 3858 eyes of 2072 subjects were tested. The test was completed in 76% of respondents. Acceptability was high. Average test time was 120.4 s. The overall mean motion sensitivity of all eyes tested was 88.49%, ±17.49. Using a cutoff level of 50%, 6.4% of all subjects tested were subnormal. The highest proportion of subnormals recorded was in Morogoro at 12.7%. Severe defects in a community best correlated with optic nerve disease prevalence, while the proportion of the defect from a higher cutoff level best correlated with overall ocular morbidity. A repeat examination in the next 5 years following ivermectin treatment will show the influence, if any, on community-wide MSST performance. Conclusion: A wide range in community scores reflected disease diversity. The MSST appears to be a useful test in community-wide screening and diagnosis as it reflects the general level of ocular pathology and specifically, optic nerve disease. [ABSTRACT FROM AUTHOR]

Despite motion of the entire retinal image that results from fixational eye-movements, the visual scene is perceived as stationary. One hypothesis to account for this observation is that normal motion sensitivity is limited by the variability of fixational eye velocity. The present experiments tested this hypothesis by comparing motion sensitivity and the variability of fixational eye velocity in corresponding meridians. Speed thresholds to detect horizontal, vertical, and rotary motion in a set of eight random-dot patches were measured, while normal observers monocularly viewed the stimulus with gaze either straight-ahead or deviated to the left by 45°. Eye-movement recordings using the search-coil technique were used to estimate the variability of eye velocity in the horizontal, vertical, and torsional meridians during fixation. As reported previously by Murakami (), the averaged thresholds for horizontal and vertical motion correlated with the averaged variability of eye velocity in the horizontal and vertical meridians when observers looked straight-ahead. However, no relationship existed between the threshold for rotary motion and the variability of eye velocity in the torsional meridian. Furthermore, no relationship existed between the motion threshold and the variability of eye velocity in any meridian during fixation in lateral eccentric gaze. These results are only partly consistent with the hypothesis that fixation variability limits motion sensitivity. [ABSTRACT FROM AUTHOR]

Adults have little difficulty perceiving objects as complete despite occlusion, but newborn infants perceive moving partly occluded objects solely in terms of visible surfaces. The developmental mechanisms leading to perceptual completion have never been adequately explained. Here, the authors examine the potential contributions of oculomotor behavior and motion sensitivity to perceptual completion performance in individual infants. Young infants were presented with a center-occluded rod. moving back and forth against a textured background, to assess perceptual completion. Infants also participated in tasks to assess oculomotor scanning patterns and motion direction discrimination. Individual differences in perceptual completion performance were strongly correlated with scanning patterns but were unrelated to motion direction discrimination. The authors present a new model of development of perceptual completion that posits a critical role for targeted visual scanning, an early developing oculomotor action system. [ABSTRACT FROM AUTHOR]

To investigatethe clinical features and naturalhistory of mal de debarquement(MdD). Retrospective casereview with follow-up questionnaireand telephone interviews. University Neurotology Clinic. Patients seen between1980 and 2006 who developed apersistent sensation of rocking orswaying for at least 3 days after exposureto passive motion. Clinical features,diagnostic testing, and questionnaireresponses. Of 64 patients(75 % women) identifiedwith MdD, 34 completed follow-upquestionnaires and interviews in2006. Most patients had normalneurological exams, ENGs andbrain MRIs. The average age of thefirst MdD episode was 39 ± 13years. A total of 206 episodes wereexperienced by 64 patients. Ofthese, 104 episodes (51 %) lasted> 1 month; 18 %, > 1 year; 15 %, > 2years; 12 %, > 4 years, and 11 %, > 5years. Eighteen patients (28 %) subsequentlydeveloped spontaneousepisodes of MdD-like symptomsafter the initial MdD episode.There was a much higher rate ofmigraine in patients who went onto develop spontaneous episodes(73 %) than in those who did not(22 %). Subsequent episodes werelonger than earlier ones in mostpatients who had multiple episodes.Re-exposure to passivemotion temporarily decreasedsymptoms in most patients (66 %).Subjective intolerance to visualmotion increased (10 % to 66 %)but self-motion sensitivity did not(37 % to 50 %) with onset of MdD. The majority of MdDepisodes lasting longer than 3 daysresolve in less than one year but theprobability of resolution declineseach year. Many patients experiencemultiple MdD episodes. Somepatients develop spontaneousepisodes after the initial motiontriggeredepisode with migrainebeing a risk factor. [ABSTRACT FROM AUTHOR]

Primary objective: To determine whether critical flicker frequency (CFF) thresholds are abnormal in individuals with mild traumatic brain injury (TBI) and, if so, if they are correlated with the degree of reported motion and light sensitivity. Methods and procedures: The foveal CFF threshold was assessed in individuals with mild TBI (n = 18) having varying degrees of reported light and motion sensitivity. Mean CFF values were obtained using the ascending and descending psychophysical method of limits with binocular viewing at 40 cm. A 7-item, rating-scale questionnaire was used to assess the degree of light and motion sensitivity. These parameters were also assessed in a large visually-normal, non-TBI cohort. Main outcomes and results: CFF in the mild TBI group was not significantly different across age groups from the visually-normal, non-TBI cohort. However, mean CFF among the mild TBI subjects was significantly higher for the 'light sensitive' and 'motion sensitive' sub-groups when compared to the 'not light sensitive' and 'not motion sensitive' sub-groups. The majority of TBI subjects manifested both light and motion sensitivity. Conclusion: CFF was found to be related to the reported degree of light and motion sensitivity in individuals with mild TBI. Neurological disinhibition as a result of brain injury may be causal of the subjective hypersensitivity to light and motion in the presence of normal CFF. [ABSTRACT FROM AUTHOR]

Conclusions. The Dutch (Belgium) translation of the Dizziness Handicap Inventory (DHI) has proven to be as consistent as the original version. In addition to the three original subscales, factor analysis revealed a fourth component scoring self-perceived effects of insufficient functioning of the vestibulo-ocular reflex (VOR). Focus should be on the DHI total score in order to compare future results with the existing literature. Objective. To conduct a factor analysis and to determine its internal consistency. Materials and methods. Charts of 214 outpatients, referred with dizziness or imbalance of vestibular and non-vestibular origin, were reviewed. Results. The Cronbach's alpha coefficients for internal consistency were high for the total scale and good for the subscales. Corrected item-total correlations ranged from 0.71 for 'restricted travelling' to 0.29 for 'difficulties reading', when items were correlated with their respective subtotals, and ranged from 0.69 (restricted participation in social activities) to 0.33 (stressed relationships), when correlated with the total score. A principal component analysis with orthogonal rotation was conducted, suggesting a four-factor solution. Two factors were related to vestibular handicap, referring to the original functional and emotional subcategories. The remaining two factors related to vestibular disability, documenting motion sensitivity (original physical subscale) and insufficient VOR functioning. [ABSTRACT FROM AUTHOR]

Although much evidence indicates that young infants perceive unitary objects by analyzing patterns of motion, infants’ abilities to perceive object unity by analyzing Gestalt properties and by integrating distinct views of an object over time are in dispute. To address these controversies, four experiments investigated adults’ and infants’ perception of the unity of a center-occluded, moving rod with misaligned visible edges. Both alignment information and depth information affected adults’ and infants’ perception of object unity in similar ways, and infants perceived object unity by integrating information about object features over time. However, infants perceived a moving, misaligned, three-dimensional object as indeterminate in its connectedness, whereas adults perceived it as connected behind the occluder. These findings indicate that the effectiveness of common motion in specifying unified surfaces across an occluder is reduced by misalignment of edges. Alignment information enhances perception of object unity either by serving directly as information for unity or by optimizing the detectability of motion-carried information for unity. In addition, young infants are able to retain information about edge orientation over short intervals in determining connectedness via a process of spatiotemporal integration. [Copyright &y& Elsevier]

Little is known about vestibular-related timing processes in patients with disequilibrium. Patients with a history of migraine headaches often complain of significant motion sensitivity and long-term vague imbalance inconsistent with a peripheral vestibular disorder. Some of these people have episodic spells of severe vertigo termed 'vestibular migraines'. Other patients have no history of migraine but do report significant motion sensitivity. Motion sensitivity has typically been explained as a mismatch between the amplitude of vestibular and other (typically visual) sensory inputs. Another possibility is that motion sensitive patients may suffer from a mismatch in the temporal integration of vestibular and other sensory inputs. Here, we compared the temporal binding window (TBW) of vestibular + auditory stimuli in normal subjects, subjects with motion sensitivity, and those with both migraine and motion sensitivity. We asked subjects undergoing earth-vertical sinusoidal rotations at 0.5 Hz, 128°/s to identify whether a metronome-like series of tone bursts was synchronous with their cyclic motion. We calculated the TBW as the range in time encompassing the middle 68% of the area under the psychometric curve. The TBW in normal subjects was 312 ± 135 ms (mean ± SD), in subjects with motion sensitivity was 454 ± 103 ms, and in subjects with migraine and motion sensitivity was 451 ± 124 ms. The TBW of normal subjects was significantly shorter than the other groups. Temporal errors in perception, as manifested by a prolongation of the TBW, are a plausible mechanism for imbalance in patients with migraine and motion sensitivity. [ABSTRACT FROM AUTHOR]