scholarly journals Feature representation under crowding in V1 and V4 neuronal populations

2021 ◽  
Author(s):  
Christopher A Henry ◽  
Adam Kohn
Keyword(s):  
Visual Processing ◽  
Cortical Neurons ◽  
Information Loss ◽  
Feature Representation ◽  
Spatial Integration ◽  
Neural Basis ◽  
Sensory Stimuli ◽  
Neuronal Populations ◽  
Visual Cortical ◽  
Object Features

Visual perception depends strongly on spatial context. A profound example is visual crowding, whereby the presence of nearby stimuli impairs discriminability of object features. Despite extensive work on both perceptual crowding and the spatial integrative properties of visual cortical neurons, the link between these two aspects of visual processing remains unclear. To understand better the neural basis of crowding, we recorded simultaneously from neuronal populations in V1 and V4 of fixating macaque monkeys. We assessed the information about the orientation of a visual target available from the measured responses, both for targets presented in isolation and amid distractors. Both single neuron and population responses had less information about target orientation when distractors were present. Information loss was moderate in V1 and more substantial in V4. Information loss could be traced to systematic divisive and additive changes in neuronal tuning. Tuning changes were more severe in V4; in addition, tuning exhibited greater context-dependent distortions in V4, further restricting the ability of a fixed sensory readout strategy to extract accurate feature information across changing environments. Our results provide a direct test of crowding effects at different stages of the visual hierarchy, reveal how these effects alter the spiking activity of cortical populations by which sensory stimuli are encoded, and connect these changes to established mechanisms of neuronal spatial integration.

scholarly journals Adaptation in the visual cortex: a case for probing neuronal populations with natural stimuli

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1246 ◽  
Author(s):  
Michoel Snow ◽  
Ruben Coen-Cagli ◽  
Odelia Schwartz
Keyword(s):  
Cortical Neurons ◽  
Natural Environments ◽  
Single Neurons ◽  
Neural Responses ◽  
Complete Understanding ◽  
Sensory Stimuli ◽  
Neuronal Populations ◽  
Natural Stimuli ◽  
The Past ◽  
Visual Cortical

The perception of, and neural responses to, sensory stimuli in the present are influenced by what has been observed in the past—a phenomenon known as adaptation. We focus on adaptation in visual cortical neurons as a paradigmatic example. We review recent work that represents two shifts in the way we study adaptation, namely (i) going beyond single neurons to study adaptation in populations of neurons and (ii) going beyond simple stimuli to study adaptation to natural stimuli. We suggest that efforts in these two directions, through a closer integration of experimental and modeling approaches, will enable a more complete understanding of cortical processing in natural environments.

Joint-encoding of motion and depth by visual cortical neurons: neural basis of the Pulfrich effect

10.1038/87462 ◽  
2001 ◽  
Vol 4 (5) ◽  
pp. 513-518 ◽  
Author(s):  
Akiyuki Anzai ◽  
Izumi Ohzawa ◽  
Ralph D. Freeman
Keyword(s):  
Cortical Neurons ◽  
Neural Basis ◽  
Pulfrich Effect ◽  
Visual Cortical ◽  
Joint Encoding

scholarly journals Low rank mechanisms underlying flexible visual representations

2020 ◽  
Vol 117 (47) ◽  
pp. 29321-29329 ◽  
Author(s):  
Douglas A. Ruff ◽  
Cheng Xue ◽  
Lily E. Kramer ◽  
Faisal Baqai ◽  
Marlene R. Cohen
Keyword(s):  
Visual Cortex ◽  
Cognitive Processes ◽  
Task Switching ◽  
Visual Processing ◽  
Neuronal Population ◽  
Low Rank ◽  
Visual Neurons ◽  
Sensory Stimuli ◽  
Neuronal Populations ◽  
Wide Range

Neuronal population responses to sensory stimuli are remarkably flexible. The responses of neurons in visual cortex have heterogeneous dependence on stimulus properties (e.g., contrast), processes that affect all stages of visual processing (e.g., adaptation), and cognitive processes (e.g., attention or task switching). Understanding whether these processes affect similar neuronal populations and whether they have similar effects on entire populations can provide insight into whether they utilize analogous mechanisms. In particular, it has recently been demonstrated that attention has low rank effects on the covariability of populations of visual neurons, which impacts perception and strongly constrains mechanistic models. We hypothesized that measuring changes in population covariability associated with other sensory and cognitive processes could clarify whether they utilize similar mechanisms or computations. Our experimental design included measurements in multiple visual areas using four distinct sensory and cognitive processes. We found that contrast, adaptation, attention, and task switching affect the variability of responses of populations of neurons in primate visual cortex in a similarly low rank way. These results suggest that a given circuit may use similar mechanisms to perform many forms of modulation and likely reflects a general principle that applies to a wide range of brain areas and sensory, cognitive, and motor processes.

scholarly journals Spontaneous behaviors drive multidimensional, brainwide activity

Science ◽  
2019 ◽  
Vol 364 (6437) ◽  
pp. eaav7893 ◽  
Author(s):  
Carsen Stringer ◽  
Marius Pachitariu ◽  
Nicholas Steinmetz ◽  
Charu Bai Reddy ◽  
Matteo Carandini ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spontaneous Activity ◽  
Random Noise ◽  
Population Activity ◽  
Sensory Stimuli ◽  
Neuronal Populations ◽  
Ongoing Behavior ◽  
Visual Cortical ◽  
Mouse Visual Cortex ◽  
External Stimuli

Neuronal populations in sensory cortex produce variable responses to sensory stimuli and exhibit intricate spontaneous activity even without external sensory input. Cortical variability and spontaneous activity have been variously proposed to represent random noise, recall of prior experience, or encoding of ongoing behavioral and cognitive variables. Recording more than 10,000 neurons in mouse visual cortex, we observed that spontaneous activity reliably encoded a high-dimensional latent state, which was partially related to the mouse’s ongoing behavior and was represented not just in visual cortex but also across the forebrain. Sensory inputs did not interrupt this ongoing signal but added onto it a representation of external stimuli in orthogonal dimensions. Thus, visual cortical population activity, despite its apparently noisy structure, reliably encodes an orthogonal fusion of sensory and multidimensional behavioral information.

scholarly journals Playing the electric light orchestra—how electrical stimulation of visual cortex elucidates the neural basis of perception

2015 ◽  
Vol 370 (1677) ◽  
pp. 20140206 ◽  
Author(s):  
Nela Cicmil ◽  
Kristine Krug
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Information Integration ◽  
Cortical Neurons ◽  
Extrastriate Cortex ◽  
Neural Basis ◽  
Electrical Microstimulation ◽  
Neuronal Mechanisms ◽  
Visual Cortical ◽  
Stimulation Of

Vision research has the potential to reveal fundamental mechanisms underlying sensory experience. Causal experimental approaches, such as electrical microstimulation, provide a unique opportunity to test the direct contributions of visual cortical neurons to perception and behaviour. But in spite of their importance, causal methods constitute a minority of the experiments used to investigate the visual cortex to date. We reconsider the function and organization of visual cortex according to results obtained from stimulation techniques, with a special emphasis on electrical stimulation of small groups of cells in awake subjects who can report their visual experience. We compare findings from humans and monkeys, striate and extrastriate cortex, and superficial versus deep cortical layers, and identify a number of revealing gaps in the ‘causal map′ of visual cortex. Integrating results from different methods and species, we provide a critical overview of the ways in which causal approaches have been used to further our understanding of circuitry, plasticity and information integration in visual cortex. Electrical stimulation not only elucidates the contributions of different visual areas to perception, but also contributes to our understanding of neuronal mechanisms underlying memory, attention and decision-making.

scholarly journals Altered functional interactions between neurons in primary visual cortex of macaque monkeys with experimental amblyopia

2019 ◽  
Author(s):  
Katerina Acar ◽  
Lynne Kiorpes ◽  
J. Anthony Movshon ◽  
Matthew A. Smith
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Cortical Neurons ◽  
Visual Sensitivity ◽  
Visual Responses ◽  
Macaque Monkeys ◽  
Fellow Eye ◽  
Neuronal Populations ◽  
Evoked Activity

AbstractAmblyopia, a disorder in which vision through one of the eyes is degraded, arises because of defective processing of information by the visual system. Amblyopia often develops in humans after early misalignment of the eyes (strabismus), and can be simulated in macaque monkeys by artificially inducing strabismus. In such amblyopic animals, single-unit responses in primary visual cortex (V1) are appreciably reduced when evoked by the amblyopic eye compared to the other (fellow) eye. However, this degradation in single V1 neuron responsivity is not commensurate with the marked losses in visual sensitivity and resolution measured behaviorally. Here we explored the idea that changes in patterns of coordinated activity across populations of V1 neurons may contribute to degraded visual representations in amblyopia, potentially making it more difficult to read out evoked activity to support perceptual decisions. We studied the visually-evoked activity of V1 neuronal populations in three macaques (M. nemestrina) with strabismic amblyopia and in one control. Activity driven through the amblyopic eye was diminished, and these responses also showed more interneuronal correlation at all stimulus contrasts than responses driven through the fellow eye or responses in the control. A decoding analysis showed that responses driven through the amblyopic eye carried less visual information than other responses. Our results suggest that part of the reduced visual capacity of amblyopes may be due to changes in the patterns of functional interaction among neurons in V1.New and noteworthyAmblyopia is a developmental disorder of visual processing that reduces visual function and changes the visual responses of cortical neurons in macaque monkeys. The neuronal and behavioral changes are not always well correlated. We found that the interactions among neurons in the visual cortex of monkeys with amblyopia are also altered. These changes may contribute to amblyopic visual deficits by diminishing the amount of information relayed by neuronal populations driven by the amblyopic eye.

scholarly journals Learning and attention increase visual response selectivity through distinct mechanisms

2021 ◽  
Author(s):  
Jasper Poort ◽  
Katharina A. Wilmes ◽  
Antonin Blot ◽  
Angus Chadwick ◽  
Maneesh Sahani ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Visual Response ◽  
Attention Switching ◽  
Sensory Stimuli ◽  
Neuronal Populations ◽  
Cell Class ◽  
Local Functional ◽  
Selective Enhancement ◽  
Switching Task ◽  
Circuit Modelling

SummarySelectivity of cortical neurons for sensory stimuli can increase across days as animals learn their behavioral relevance, and across seconds when animals switch attention. While both phenomena are expressed in the same cortical circuit, it is unknown whether they rely on similar mechanisms. We imaged activity of the same neuronal populations in primary visual cortex as mice learned a visual discrimination task and subsequently performed an attention switching task. Selectivity changes due to learning and attention were uncorrelated in individual neurons. Selectivity increases after learning mainly arose from selective suppression of responses to one of the task relevant stimuli but from selective enhancement and suppression during attention. Learning and attention differentially affected interactions between excitatory and PV, SOM and VIP inhibitory cell classes. Circuit modelling revealed that cell class-specific top-down inputs best explained attentional modulation, while the reorganization of local functional connectivity accounted for learning related changes. Thus, distinct mechanisms underlie increased discriminability of relevant sensory stimuli across longer and shorter time scales.

Linking sensory neurons to visually guided behavior: Relating MST activity to steering in a virtual environment

2013 ◽  
Vol 30 (5-6) ◽  
pp. 315-330 ◽  
Author(s):  
SETH W. EGGER ◽  
KENNETH H. BRITTEN
Keyword(s):  
Cortical Neurons ◽  
Traditional Approach ◽  
Sensory System ◽  
Sensory Information ◽  
Neuronal Population ◽  
Difficult Problem ◽  
Lower Envelope ◽  
Visually Guided ◽  
Medial Superior Temporal ◽  
Visual Cortical

AbstractMany complex behaviors rely on guidance from sensations. To perform these behaviors, the motor system must decode information relevant to the task from the sensory system. However, identifying the neurons responsible for encoding the appropriate sensory information remains a difficult problem for neurophysiologists. A key step toward identifying candidate systems is finding neurons or groups of neurons capable of representing the stimuli adequately to support behavior. A traditional approach involves quantitatively measuring the performance of single neurons and comparing this to the performance of the animal. One of the strongest pieces of evidence in support of a neuronal population being involved in a behavioral task comes from the signals being sufficient to support behavior. Numerous experiments using perceptual decision tasks show that visual cortical neurons in many areas have this property. However, most visually guided behaviors are not categorical but continuous and dynamic. In this article, we review the concept of sufficiency and the tools used to measure neural and behavioral performance. We show how concepts from information theory can be used to measure the ongoing performance of both neurons and animal behavior. Finally, we apply these tools to dorsal medial superior temporal (MSTd) neurons and demonstrate that these neurons can represent stimuli important to navigation to a distant goal. We find that MSTd neurons represent ongoing steering error in a virtual-reality steering task. Although most individual neurons were insufficient to support the behavior, some very nearly matched the animal’s estimation performance. These results are consistent with many results from perceptual experiments and in line with the predictions of Mountcastle’s “lower envelope principle.”

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