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In this issue of Neuron, Jordan and Keller (2020) explore subthreshold computations underlying predictive coding using whole-cell recordings in mouse visual cortex. Their findings suggest that layer 2/3, but not layer 5/6, neurons compute prediction errors by subtracting predicted and actual visual flow inputs generated by locomotion.

All Smartphones have become a necessity rather than a utility. Not a single person can deny that our mobile phones go wherever we go. Phones were created as a means for more accessible communication over distance. The purpose of a phone has dramatically changed over the years by the technology advancement and the arrival of smartphones which provides many applications and make us stick to it. This study understands the correlation between the activity of eyes and flow level of the eye. Also, how the visual activity parameters are calculated will be discussed. This study enhances the understanding of visual fatigue caused due to the digital medium. Examine the subject’s eye flow level with smartphone and VDT utilisation. Besides, the application of learning algorithms, including machine learning/deep learning is massive with regards to analysing visual fatigue. The purpose of this study also going to discuss the application of both machine learning and deep learning on analysing visual fatigue caused by Digital Medium.

This study tested the effects of a motion-coupled display on task performance and self-reports of motion sickness for subjects experiencing motion at a frequency and intensity previously found to be nauseogenic. Subjects were randomly assigned to a control condition or a treatment condition. Both groups performed a simple computer game (Tetris) for a 30-minute period while moving forward and backward at 0.2 Hz in an enclosed chamber. In the treatment condition, a visual flow field whose movement was coupled to the motion of the enclosed test chamber was displayed behind and around a window in which subjects performed the computer game. For the control condition, the visual flow field elements were kept stationary. Contrary to expectations, no differences were found between the two groups on self-reported motion sickness symptoms; however, the treatment group performed significantly better than the control group on the computer game.

Despite considerable efforts to diminish critical spatial disorientation incidents during flight, they persist at constant rate. In instrument meteorological conditions, significantly enhanced support of spatial orientation (SO) could be achieved by displays of peripheral visual flow with conformal horizon. Focused depth related effectiveness of peripheral visual flow needs however to be investigated because of the pilot is changing depth focus in the cockpit. This was investigated in two experiments by manipulating relative depths of peripheral/central presentations and measuring their effects on postural instability. The results show that focused depth close-by with peripheral displays further away have less impact on perceived SO than focusing further away with peripheral displays closer. We conclude that focused depth drives the effects of peripheral visual flow on SO, and implementation implications are shortly discussed.

Foraging honeybees find their way from their hive to their food in a stereotypical manner using up to four place-finding servomechanisms in sequence: (1) They first fly a vector (straight-line distance and direction) from their home to the vicinity of the target. Direction is determined by the sun compass and by distant landmarks, while distance is estimated by visual flow. (2) They then beacon in on a landmark near the target location. (3) En route toward the landmark, they may adopt a sensorimotor trajectory that takes them toward the target. (4) Near the expected target location, they attempt image matching, which involves trying to put surrounding landmarks at the correct positions on their eyes. In doing image matching, they fly facing a stereotypical direction, a strategy that makes it unnecessary to translate retinal coordinates into another coordinate system.

We studied the effects of visual scenery modulation related to path inclination on gait performance. So far, seven young healthy adults were tested with an advanced virtual reality (VR) system. While walking on treadmill in a self-paced mode in straight, uphill and downhill inclinations, the subjects were exposed to visual scenery providing visual flow presenting either conflicting or matching visual inclination to the treadmill inclination. When visual scenery changed to uphill or downhill scenery, gait was immediately affected, even when no corresponding treadmill inclination. Further research is required to understand if this effect can be employed to facilitate rehabilitation programs.

SUMMARYFlies, like all animals that depend on vision to navigate through the world, must integrate the optic flow created by self-motion with the images generated by prominent features in their environment. Although much is known about the responses of Drosophila melanogaster to rotating flow fields, their reactions to the more complex patterns of motion that occur as they translate through the world are not well understood. In the present study we explore the interactions between two visual reflexes in Drosophila: object fixation and expansion avoidance. As a fly flies forward, it encounters an expanding visual flow field. However, recent results have demonstrated that Drosophila strongly turn away from patterns of expansion. Given the strength of this reflex, it is difficult to explain how flies make forward progress through a visual landscape. This paradox is partially resolved by the finding reported here that when undergoing flight directed towards a conspicuous object, Drosophila will tolerate a level of expansion that would otherwise induce avoidance. This navigation strategy allows flies to fly straight when orienting towards prominent visual features.

After a review of the purpose and biological background of Head Direction Cells, and existing models of them, we introduce an improved neural model that integrates visual flow information with the vestibular inputs found in earlier models. Simulation results using real video inputs are presented to explore and validate the new model, the evolutionary advantages for the proposed arrangement are noted, its utility for use in robot controllers is discussed, and suggestions are made for further work in this area.

It has been suggested that much of animal navigation takes place without reference to visual information in the environment (Gallistel 1990). A geocentric dead reckoning process, which tracks the travel trajectory of animals internally with only periodic reference to external visual cues, is thought to be a major component underlying animal navigation. Following Gibson (1979),and in contrast to the non-visual emphesis for animal navigation, two types of structure in visual flow are thought to be important for human navigation: perspective structure, which specifies self-motion and self-to-object relations, and invariant structure, which specifies object-to-object relations. A review of the cognitive mapping literature for sighted and blind human adults suggests that the invariant structure in visual flow is important to the formation of cognitive maps, or survey knowledge, of environments. In contrast, a geocentric dead reckoning process which uses the self-movement information provided by perspective structure may be importantly involved in the formation of route knowledge. Findings reviewed from studies of the development of navigational skills in children are consistent with the idea that cognitive mapping skills develop in concert with the ability to perceptually differentiate perspective and invariant structure in visual flow.

Traversed distance perception involves estimating the extent of self-motion as one travels from one position in space to another. As such, it is a multi-modal experience in which information from both visual flow and locomotor cues (i.e. proprioceptive, efference copy and vestibular cues) jointly specify the magnitude of self-motion. While recent evidence has demonstrated the extent to which each of these cues can be used independently to estimate traversed distance, relatively little is known about how they are integrated when simultaneously present. Evaluating multi-modal cue integration in the context of dynamic locomotor behaviour is important to both understanding issues related to self-motion perception, as well as perceptual-motor coupling in real and virtual environments.

To reveal the underlying cellular mechanisms of the noise tolerance in the discrimination of the direction of visual flow, we analyzed both response behaviors of directionally selective cells in the d-MST of the macaque and discrimination properties of human subjects for visual flow by using large-field texture flow. The stimulus was a 32/spl times/32-pixel random checker pattern refreshed at every 16 msec in which coherency of the motion of the texture was systematically controlled by a special purpose computer. The discrimination performance of the human observers showed a high degree of tolerance for directional noise. Field-type D-cells in d-MST also showed response properties which closely resembled human discrimination performance. These results strongly suggest that cells in d-MST area play a crucial role in the generation of signals for perception of global motion.

The mechanisms involved in the cortical processing of large-field motion patterns still remain widely unclear. In particular, the integrative action of, e.g., cells and their receptive fields, their specificity, the topographic mapping of activity patterns, and the reciprocal interareal interaction needs to be investigated. We utilize a recently discovered relative motion illusion as a tool to gain insights into the neural mechanisms that underlie the integration and segregation of such motion fields occurring during navigation, steering and fixation control. We present a model of recurrent interaction of areas V1, MT, and MSTd along the dorsal cortical pathway utilizing a space-variant mapping of flow patterns. In accordance with psychophysical findings, our results provide evidence that recurrent gain control mechanisms together with the non-linear warping of the visual representation are essential to group or disambiguate motion responses. This provides further evidence for the importance of feedback interactions between cortical areas.

Grasping behavior starts from a set of biologically-determined tonic and postural adaptations that constitute the fulcrum of the movement. The analysis of these starting points and their transformation through the first months of life allows to better situate grasping behavior.

Counterphase gratings, and several other stimuli which consist of equal components of motion in both directions, appeared to drift foveofugally, rather than foveopetally, when presented to the retinal periphery. This ‘foveofugal drift effect’ was demonstrated by descriptive and nulling techniques and its magnitude was shown to vary across subjects. The effect was fairly brief under continuous fixation. Several lines of evidence suggested that eye movements were not responsible for the effect. The phenomenon implies a directional asymmetry in the human visual system which may be related to our consistent exposure to expanding patterns of visual flow.

A computational model for visual flow-field cueing and self-motion estimation is developed and simulated. The model is predicated on the notion that the pilot makes noisy, sampled measurements on the spatially distributed visual flow-field surrounding him and, on the basis of these measurements, generates estimates of his own linear and angular terrain-relative velocities which optimally satisfy, in a least-squares sense, the visual kinematic flow constraints. The least-squares formulation is applicable to general observer motions and viewing geometries; it is projection-plane independent and rational in its treatment of redundant and noisy flow cues. A subsidiary but significant output of the model is an `impact time' map, and observer-centered spatially scaled replica of the viewed surface. Simulations are presented to demonstrate the parametric sensitivity and ability to model relevant human visual performance data. Preliminary simulation results of human visual performance are encouraging.

Contrary to a previous assumption, the center of the expanding pattern of visual flow is not generally useful as an aid in judging the direction of self motion since its direction depends on the direction of gaze. For some visual environments, however, the point of maximum rate of change of magnification in the retinal image coincides with the direction of self motion, independently of the direction of gaze. This visual indicator could be used to judge the direction of self motion.

The paper presents experimental evidence for homing by path integration in a bird. Using a mammalian model case, the essentials of a cybernetical theory of this type of navigation are developed. As a consequence of its application to the extant data on geese, the necessary information about the translatory component of the animal’s movement along its path appears to be provided by the visual system, viz. the translatory component of the visual flow, whereas the rotatory information must (also) have non-visual sources, e.g. the semicircular canals or the magnetic field.

An experimental prototype for the Bionic Eyeglass will be demonstrated including three sample functions: pedestrian crosswalk detection, light detection and a basic color recognition. The prototype is built on the Bi-i visual computer, and uses a commercial cellular phone as a front-end towards the user. The visual flow is streamed from the camera of the cellular phone wirelessly to the Bi-i where it is processed, and the result is communicated through the speakers of the phone. Scalar or binary outputs are provided for the first two functions by beeping tones, whereas a basic color name is given for the last one.

Self-motion induces spontaneous eye movements which serve the purpose of stabilizing the visual image on the retina. Previous studies have mainly focused on their reflexive nature and how the perceptual system disentangles visual flow components caused by eye movements and self-motion. Here, we investigated the role of eye movements in distance reproduction (path integration). We used bimodal (visual-auditory)-simulated self-motion: visual optic flow was paired with an auditory stimulus whose frequency was scaled with simulated speed. The task of the subjects in each trial was, first, to observe the simulated self-motion over a certain distance (Encoding phase) and, second, to actively reproduce the observed distance using only visual, only auditory, or bimodal feedback (Reproduction phase). We found that eye positions and eye speeds were strongly correlated between the Encoding and the Reproduction phases. This was the case even when reproduction relied solely on auditory information and thus no visual stimulus was presented. We believe that these correlations are indicative of a contribution of eye movements to path integration.