Biology subjects

Nategh, N.

Publications and source records attributed to Nategh, N..

5 recordsLinked to original sources

bioRxiv2026

A population readout of extrastriate activity reveals biased and smoothed temporal representations across saccades

Perception of visual time is transiently distorted around saccadic eye movements, yet the neuronal mechanisms constructing perisaccadic representations of time remain unclear. Here, we investigate how perisaccadic temporal information is encoded and read out in extrastriate cortex, by combining electrophysiological recordings in V4 and MT neuronal population in macaque monkeys under high spatiotemporal resolution visual stimulation, and a statistical modeling framework capturing perisaccadic response modulations at single-trial precision. Our analyses show that perisaccadic neuronal responses systematically shift the temporal representation of presaccadic stimuli within receptive fields-biasing them toward earlier times, and also reduce temporal sensitivity for presaccadic stimuli-impairing discrimination of stimulus onset times. Model-based readout using time-varying spatiotemporal sensitivity maps in neuronal ensembles enables quantitative characterization of these effects and identifies their specific neuronal response components at millisecond resolution. In silico manipulations further demonstrate a causal role of representational bias in reducing temporal sensitivity. These findings suggest that extrastriate cortex implements an active encoding strategy to stabilize presaccadic temporal information by favoring the most recent reliable input, revealing a fundamental tradeoff between temporal precision and robustness that supports a continuous visual percept across saccades. This finding also establishes a general role for extrastriate populations in constructing the perception of visual time.

neuroscience↗

bioRxiv2026

Limits of V4 perisaccadic firing rate modulations in explaining perceptual mislocalization

Whether and how various visual sensory areas contribute to the perceived location of visual stimuli remains unknown. To test the role of neurons in extrastriate area V4 in generating alterations in spatial perception during saccadic eye movements (saccades), we examined perisaccadic mislocalization--the perceptual phenomenon in which visual stimuli appearing around the time of a saccade are perceived at a different position than their actual location. We designed and implemented a combined behavioral and electrophysiological framework in non-human primates to directly relate trial-by-trial spatial perception reports during saccades to neuronal firing rates in V4 populations. We measured monkeys perception of stimulus location behaviorally and found perisaccadic mislocalization opposite to the saccade direction. We also quantified population responses by computing the center of mass of firing rate activity across probe locations for V4 neurons with receptive fields close to the saccade target. While perisaccadic neuronal responses showed shifts toward the saccade target, these shifts did not systematically vary with the magnitude of perceptual mislocalization across trials. In conclusion, receptive field shifts based on the perisaccadic firing rate of V4 neurons are not sufficient to account for the magnitude of perceptual mislocalization in each trial, suggesting that more complex neural representation of perisaccadic visual information may be critical for linking extrastriate neural activity to saccade-induced perception.

neuroscience↗

bioRxiv2023

Neural correlates of perisaccadic visual mislocalization in extrastriate cortex

When interacting with the visual world using saccadic eye movements (saccades), the perceived location of visual stimuli becomes biased, a phenomenon called perisaccadic mislocalization, which is indeed an exemplar of the brains dynamic representation of the visual world. However, the neural mechanism underlying this altered visuospatial perception and its potential link to other perisaccadic perceptual phenomena have not been established. Using a combined experimental and computational approach, we were able to quantify spatial bias around the saccade target (ST) based on the perisaccadic dynamics of extrastriate spatiotemporal sensitivity captured by statistical models. This approach could predict the perisaccadic spatial bias around the ST, consistent with the psychophysical studies, and revealed the precise neuronal response components underlying representational bias. These findings also established the crucial role of response remapping toward ST representation for neurons with receptive fields far from the ST in driving the ST spatial bias. Moreover, we showed that, by allocating more resources for visual target representation, visual areas enhance their representation of the ST location, even at the expense of transient distortions in spatial representation. This potential neural basis for perisaccadic ST representation, also supports a general role for extrastriate neurons in creating the perception of stimulus location.

neuroscience↗

bioRxiv2020

A Sensory Memory to Preserve Visual Representations Across Eye Movements

During eye movements, the continuous flow of visual information is frequently disrupted due to abrupt changes of the retinal image, yet our perception of the visual world is uninterrupted. In order to identify the neuronal response components necessary for the integration of perception across eye movements, we developed a computational model to trace the changes in the visuospatial sensitivity of neurons in the extrastriate cortex of macaque monkeys with high temporal precision. Employing the model, we examined the perceptual implications of these changes and found that by maintaining a memory of the visual scene, extrastriate neurons produce an uninterrupted representation of the visual world. These results reveal how our brain exploits available information to maintain the sense of vision in the absence of visual information.

neuroscience↗

bioRxiv2018

Diverse nonlinear modulation of visual features by retinal amacrine cells

The prevailing hierarchical view of the visual system consists of parallel circuits that begin in the retina, which then sum effects across sequential levels, increasing in complexity. Yet a separate type of interaction, whereby one visual pattern changes the influence of another, known as modulation, has received much less attention in terms of its circuit mechanisms. Retinal amacrine cells are a diverse class of inhibitory interneurons that are thought to have modulatory effects, but we lack a general understanding of their functional types. Using dynamic causal experiments in the salamander retina perturbing amacrine cells along with an unsupervised computational framework, we find that amacrine cell modulatory effects cluster into two distinct types. One type controls ganglion cell sensitivity to individual visual features, and a second type controls the ganglion cells output gain, acting to gate all features. These results establish three separate general roles of amacrine cells - to generate primary visual features, to use context to select specific visual features and to gate retinal output.

neuroscience↗