Motion Processing in Primates

Manning, Tyler S; Britten, Kenneth H.

doi:10.1093/acrefore/9780190264086.013.76

Cited by 5 publications

(3 citation statements)

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“…It is well known that the visual system integrates multiple cues to infer visual properties for mid-level object properties, such as depth or object shape 1,4 . At a first glance, motion direction estimation may seem like a straightforward task, devoid of the need for additional evidenceafter all, why would direction-sensitive neurons not provide sufficient information for direction estimation (see, e.g., 51 , for a review)? However, as we show here, even for simple tasks the brain appears to utilize additional cues, such as spatial orientation, to reduce uncertainty.…”

Section: Discussionmentioning

confidence: 99%

Motion direction is represented as a bimodal probability distribution in the human visual cortex

Chetverikov

Jehee²

2023

Preprint

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How do humans infer motion direction from noisy sensory signals? We hypothesized that motion direction is computed not only from velocity but also spatial orientation signals - a 'streak' created by moving objects. We implemented this hypothesis in a Bayesian model, which quantifies knowledge with probability distributions, and tested its predictions using psychophysics and fMRI. Using a probabilistic pattern-based analysis, we decoded probability distributions of motion direction from trial-by-trial activity in the human visual cortex. Corroborating the predictions, the decoded distributions had a bimodal shape, with peaks that predicted the direction and magnitude of behavioral errors. Interestingly, we observed similar bimodality in the distribution of the observers' behavioral responses across trials. Together, these results suggest that observers use spatial orientation signals when estimating motion direction. More broadly, our findings indicate that the cortical representation of low-level visual features, such as motion direction, can reflect a combination of several qualitatively distinct signals.

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Section: Discussionmentioning

confidence: 99%

Motion direction is represented as a bimodal probability distribution in the human visual cortex

Chetverikov

Jehee²

2023

Preprint

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“…For example, we find that in area V4, quadratic features at the second stage of the model consists of excitatory and suppressive pairs of features that are selective for opposing directions of global motion. This is interesting because area V4 is not conventionally thought of as motion-selective area 35,36 . Nevertheless, motion signals are known to aid in object segmentation 36 and that some motion selectivity was detected in V4 neurons by prior studies 37,38 .…”

Section: Discussionmentioning

confidence: 99%

Quadratic computations maintain neural specificity to natural stimuli across stages of visual processing

Rowekamp

Sharpee

2022

Preprint

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Despite recent successes in machine vision, artificial recognition systems continue to be less robust than biological systems. The brittleness of artificial recognition system has been attributed to the linearity of the core operation that matches inputs to target patterns at each stage of the system. Here we analyze responses of neurons from the visual areas V1, V2, and V4 of the brain using the framework that incorporates quadratic computations into multi-stage models. These quadratic computations make it possible to capture local recurrent computation, and in particular, nonlinear suppressive interactions between visual features. We find that incorporating quadratic computation not only strongly improved predictive power of the resulting model, but also revealed several computation motifs that increased the selectivity of neural responses to natural stimuli. These motifs included the organization of excitatory and suppressive features along mutually exclusive hypotheses about incoming stimuli, such as orthogonal orientations or opposing motion directions. The balance between excitatory and suppressive features was largely maintained across brain regions. These results emphasize the importance and properties of quadratic computations that are necessary for achieving robust object recognition.

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“…Direction- and orientation-selective circuits in V1, which integrate spatiotemporal patterns of excitation within their receptive fields to encode motion, are necessary for the generation of smooth pursuit in primates and also provide a direction selective input to the image forming pathway. 22 , 30 A series of discrete flashes could be interpreted as motion in the context of the task, but this would not be expected to elicit a smooth pursuit. Therefore the observation of smooth pursuit in two subjects might suggest the experience of motion was more naturalistic than expected.…”

Section: Discussionmentioning

confidence: 99%

Oculomotor Responses to Dynamic Stimuli in a 44-Channel Suprachoroidal Retinal Prosthesis

Titchener

Kvansakul

Shivdasani

et al. 2020

Trans. Vis. Sci. Tech.

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Purpose To investigate oculomotor behavior in response to dynamic stimuli in retinal implant recipients. Methods Three suprachoroidal retinal implant recipients performed a four-alternative forced-choice motion discrimination task over six sessions longitudinally. Stimuli were a single white bar (“moving bar”) or a series of white bars (“moving grating”) sweeping left, right, up, or down across a 42″ monitor. Performance was compared with normal video processing and scrambled video processing (randomized image-to-electrode mapping to disrupt spatiotemporal structure). Eye and head movement was monitored throughout the task. Results Two subjects had diminished performance with scrambling, suggesting retinotopic discrimination was used in the normal condition and made smooth pursuit eye movements congruent to the moving bar stimulus direction. These two subjects also made stimulus-related eye movements resembling optokinetic reflex (OKR) for moving grating stimuli, but the movement was incongruent with stimulus direction. The third subject was less adept at the task, appeared primarily reliant on head position cues (head movements were congruent to stimulus direction), and did not exhibit retinotopic discrimination and associated eye movements. Conclusions Our observation of smooth pursuit indicates residual functionality of cortical direction-selective circuits and implies a more naturalistic perception of motion than expected. A distorted OKR implies improper functionality of retinal direction-selective circuits, possibly due to retinal remodeling or the non-selective nature of the electrical stimulation. Translational Relevance Retinal implant users can make naturalistic eye movements in response to moving stimuli, highlighting the potential for eye tracker feedback to improve perceptual localization and image stabilization in camera-based visual prostheses.

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Motion Processing in Primates

Cited by 5 publications

References 0 publications

Motion direction is represented as a bimodal probability distribution in the human visual cortex

Motion direction is represented as a bimodal probability distribution in the human visual cortex

Quadratic computations maintain neural specificity to natural stimuli across stages of visual processing

Oculomotor Responses to Dynamic Stimuli in a 44-Channel Suprachoroidal Retinal Prosthesis

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