Shape perception via a high-channel-count neuroprosthesis in monkey visual cortex

Science ◽  
2020 ◽  
Vol 370 (6521) ◽  
pp. 1191-1196 ◽  
Author(s):  
Xing Chen ◽  
Feng Wang ◽  
Eduardo Fernandez ◽  
Pieter R. Roelfsema
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Receptive Fields ◽  
Shape Perception ◽  
Area V4 ◽  
Multiple Electrodes ◽  
The World ◽  
Functional Vision ◽  
Monkey Visual Cortex

Blindness affects 40 million people across the world. A neuroprosthesis could one day restore functional vision in the blind. We implanted a 1024-channel prosthesis in areas V1 and V4 of the visual cortex of monkeys and used electrical stimulation to elicit percepts of dots of light (called phosphenes) on hundreds of electrodes, the locations of which matched the receptive fields of the stimulated neurons. Activity in area V4 predicted phosphene percepts that were elicited in V1. We simultaneously stimulated multiple electrodes to impose visible patterns composed of a number of phosphenes. The monkeys immediately recognized them as simple shapes, motions, or letters. These results demonstrate the potential of electrical stimulation to restore functional, life-enhancing vision in the blind.

Corticogeniculate neurons, corticotectal neurons, and suspected interneurons in visual cortex of awake rabbits: receptive-field properties, axonal properties, and effects of EEG arousal

1987 ◽  
Vol 57 (4) ◽  
pp. 977-1001 ◽  
Author(s):  
H. A. Swadlow ◽  
T. G. Weyand
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Receptive Field ◽  
Receptive Fields ◽  
Spontaneous Firing ◽  
Visual Responses ◽  
Firing Rates ◽  
Axonal Conduction ◽  
Conduction Velocities ◽  
Stimulation Of

The intrinsic stability of the rabbit eye was exploited to enable receptive-field analysis of antidromically identified corticotectal (CT) neurons (n = 101) and corticogeniculate (CG) neurons (n = 124) in visual area I of awake rabbits. Eye position was monitored to within 1/5 degrees. We also studied the receptive-field properties of neurons synaptically activated via electrical stimulation of the dorsal lateral geniculate nucleus (LGNd). Whereas most CT neurons had either complex (59%) or motion/uniform (15%) receptive fields, we also found CT neurons with simple (9%) and concentric (4%) receptive fields. Most complex CT cells were broadly tuned to both stimulus orientation and velocity, but only 41% of these cells were directionally selective. We could elicit no visual responses from 6% of CT cells, and these cells had significantly lower conduction velocities than visually responsive CT cells. The median spontaneous firing rates for all classes of CT neurons were 4-8 spikes/s. CG neurons had primarily simple (60%) and concentric (9%) receptive fields, and none of these cells had complex receptive fields. CG simple cells were more narrowly tuned to both stimulus orientation and velocity than were complex CT cells, and most (85%) were directionally selective. Axonal conduction velocities of CG neurons (mean = 1.2 m/s) were much lower than those of CT neurons (mean = 6.4 m/s), and CG neurons that were visually unresponsive (23%) had lower axonal conduction velocities than did visually responsive CG neurons. Some visually unresponsive CG neurons (14%) responded with saccadic eye movements. The median spontaneous firing rates for all classes of CG neurons were less than 1 spike/s. All neurons synaptically activated via LGNd stimulation at latencies of less than 2.0 ms had receptive fields that were not orientation selective (89% motion/uniform, 11% concentric), whereas most cells with orientation-selective receptive fields had considerably longer synaptic latencies. Most short-latency motion/uniform neurons responded to electrical stimulation of the LGNd (and visual area II) with a high-frequency burst (500-900 Hz) of three or more spikes. Action potentials of these neurons were of short duration, thresholds of synaptic activation were low, and spontaneous firing rates were the highest seen in rabbit visual cortex. These properties are similar to those reported for interneurons in several regions in mammalian central nervous system. Nonvisual sensory stimuli that resulted in electroencephalographic arousal (hippocampal theta activity) had a profound effect on the visual responses of many visual cortical neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Attentional modulation of intrinsic timescales in visual cortex and spatial networks

2021 ◽  
Author(s):  
Roxana Zeraati ◽  
Yan-Liang Shi ◽  
Nicholas A Steinmetz ◽  
Marc A Gieselmann ◽  
Alexander Thiele ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cognitive Task ◽  
Temporal Integration ◽  
Receptive Fields ◽  
Recurrent Network ◽  
Area V4 ◽  
Attention Tasks ◽  
Underlying Network ◽  
Network Mechanism ◽  
Spiking Activity

Neural activity fluctuates endogenously on timescales varying across the neocortex. The variation in these intrinsic timescales relates to the functional specialization of cortical areas and their involvement in the temporal integration of information. Yet, it is unknown whether the timescales can adjust rapidly and selectively to the demands of a cognitive task. We measured intrinsic timescales of local spiking activity within columns of area V4 while monkeys performed spatial attention tasks. The ongoing spiking activity unfolded across at least two distinct timescales---fast and slow---and the slow timescale increased when monkeys attended to the receptive fields location. A recurrent network model shows that multiple timescales in local dynamics arise from spatial connectivity mimicking vertical and horizontal interactions in visual cortex and that slow timescales increase with the efficacy of recurrent interactions. Our results reveal that targeted neural populations integrate information over variable timescales following the demands of a cognitive task and propose an underlying network mechanism.

Topographic map reorganization in cat area 17 after early monocular retinal lesions

2002 ◽  
Vol 19 (1) ◽  
pp. 85-96 ◽  
Author(s):  
KAZUKI MATSUURA ◽  
BIN ZHANG ◽  
TAKAFUMI MORI ◽  
EARL L. SMITH ◽  
JON H. KAAS ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Optic Disk ◽  
Area 17 ◽  
Topographic Map ◽  
Retinal Lesions ◽  
The World ◽  
Blind Spots ◽  
Made In

Neither discrete peripheral retinal lesions nor the normal optic disk produces obvious holes in one's percept of the world because the visual brain appears to perceptually “fill in” these blind spots. Where in the visual brain or how this filling in occurs is not well understood. A prevailing hypothesis states that topographic map of visual cortex reorganizes after retinal lesions, which “sews up” the hole in the topographic map representing the deprived area of cortex (cortical scotoma) and may lead to perceptual filling in. Since the map reorganization does not typically occur unless retinotopically matched lesions are made in both eyes, we investigated the conditions in which monocular retinal lesions can induce comparable map reorganization. We found that following monocular retinal lesions, deprived neurons in cat area 17 can acquire new receptive fields if the lesion occurred relatively early in life (8 weeks of age) and the lesioned cats experienced a substantial period of recovery (>3 years). Quantitative determination of the monocular and binocular response properties of reactivated units indicated that responses to the lesioned eye for such neurons were remarkably robust, and that the receptive-field properties for the two eyes were generally similar. Moreover, excitatory or inhibitory binocular interactions were found in the majority of experimental units when the two eyes were activated together. These results are consistent with the hypothesis that map reorganization after monocular retinal lesions require experience-dependent plasticity and may be involved in the perceptual filling in of blind spots due to retinal lesions early in life.

scholarly journals The DeepTune framework for modeling and characterizing neurons in visual cortex area V4

2018 ◽  
Author(s):  
Reza Abbasi-Asl ◽  
Yuansi Chen ◽  
Adam Bloniarz ◽  
Michael Oliver ◽  
Ben D.B. Willmore ◽  
...  
Keyword(s):  
Neural Network ◽  
Visual Cortex ◽  
Deep Neural Network ◽  
Predictive Accuracy ◽  
Population Analysis ◽  
Receptive Fields ◽  
Network Models ◽  
Neural Network Models ◽  
Area V4 ◽  
V4 Neurons

AbstractDeep neural network models have recently been shown to be effective in predicting single neuron responses in primate visual cortex areas V4. Despite their high predictive accuracy, these models are generally difficult to interpret. This limits their applicability in characterizing V4 neuron function. Here, we propose the DeepTune framework as a way to elicit interpretations of deep neural network-based models of single neurons in area V4. V4 is a midtier visual cortical area in the ventral visual pathway. Its functional role is not yet well understood. Using a dataset of recordings of 71 V4 neurons stimulated with thousands of static natural images, we build an ensemble of 18 neural network-based models per neuron that accurately predict its response given a stimulus image. To interpret and visualize these models, we use a stability criterion to form optimal stimuli (DeepTune images) by pooling the 18 models together. These DeepTune images not only confirm previous findings on the presence of diverse shape and texture tuning in area V4, but also provide rich, concrete and naturalistic characterization of receptive fields of individual V4 neurons. The population analysis of DeepTune images for 71 neurons reveals how different types of curvature tuning are distributed in V4. In addition, it also suggests strong suppressive tuning for nearly half of the V4 neurons. Though we focus exclusively on the area V4, the DeepTune framework could be applied more generally to enhance the understanding of other visual cortex areas.

scholarly journals Curvature domains in V4 of Macaque Monkey

2020 ◽  
Author(s):  
Jiaming Hu ◽  
Xue Mei Song ◽  
Qiannan Wang ◽  
Anna Wang Roe
Keyword(s):  
Visual Cortex ◽  
Optical Imaging ◽  
Functional Organization ◽  
Macaque Monkey ◽  
Visual Object ◽  
Shape Information ◽  
Object Shape ◽  
Area V4 ◽  
Monkey Visual Cortex ◽  
Visual Cortical

AbstractAn important aspect of visual object recognition is the ability to perceive object shape. How the brain encodes fundamental aspects of shape information remains poorly understood. Models of object shape representation describe a multi-stage process that includes encoding of contour orientation and curvature. While modules encoding contour orientation are well established (orientation domains in V1 and V2 visual cortical areas), whether there are modules for curvature is unknown. In this study, we identify a module for curvature representation in area V4 of monkey visual cortex and illustrate a systematic representation of low to high curvature and of curvature orientation, indicative of curvature hypercolumns in V4. We suggest that identifying systematic modular organizations at each stage of the visual cortical hierarchy signifies the key computations performed.SignificanceWe use intrinsic signal optical imaging in area V4 of anesthetized macaque monkey to study the functional organization of curvature representation. We find a modular basis for cue-invariant curvature representation in area V4 of monkey visual cortex and illustrate a systematic representation from low to high curvature and of curvature orientation, replete with curvature pinwheels. This is the first report of systematic functional organization for curvature representation in the visual system. The use of optical imaging has revealed at a population level spatial details of cortical responses, something which has not been evident from previous studies of single neurons. These data support a representational architecture underlying a ‘curvature hypercolumn’ in V4.

Is there a high concentration of color-selective cells in area V4 of monkey visual cortex?

1982 ◽  
Vol 47 (2) ◽  
pp. 193-213 ◽  
Author(s):  
S. J. Schein ◽  
R. T. Marrocco ◽  
F. M. de Monasterio
Keyword(s):  
Visual Cortex ◽  
Central Field ◽  
High Concentration ◽  
Field Representation ◽  
Area V4 ◽  
Area V2 ◽  
Sufficient Detail ◽  
Prelunate Gyrus ◽  
Color Selectivity ◽  
Monkey Visual Cortex

1. Recordings were made from neurons located within the central-field representation of the V4 area of extrastriate visual cortex using a semichronic, nitrous-oxide preparation; the properties of 174 cells were examined in sufficient detail to permit their classification. Cyto- and myeloarchitectural studies confirmed the identification of the area. 2. Color-selective cells with either color-biased or color-opponent properties represented about 20% of the examined population. Their incidence was not significantly different from that of similar cells encountered in penetrations into the central-field representation of area V2. 3. Most color-selective cells had color-biased properties, responding best to wave-lengths shorter than 460 nm, or longer than 580 n, or both. No examples of "green-biased" cells were found. Some color-biased cells responded to photopically matched white light, while others did not. Very few cells showed overt color-opponent responses. The spectral sensitivity of color-selective cells was not unusually narrow. 4. Cells lacking color selectivity and responding equally well to chromatic and achromatic lights of equal photopic luminosity, were the most commonly encountered cell type in penetrations of different parts of the V4 area (56%). Other than color, these cells showed stimulus preferences like those of color-selective cells. 5. One-fourth of V4 cells could not be systematically driven with the various stimuli used. This finding is consistent with recent results of recordings from the prelunate gyrus of the behaving monkey suggesting that some V4 cells receive extraretinal signals. 6. Our results do not support recent claims that V4 is specialized in the detailed analysis of color information.

The distribution of wavelength and orientation selective cells in different areas of monkey visual cortex

1983 ◽  
Vol 217 (1209) ◽  
pp. 449-470 ◽  
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Macaque Monkey ◽  
Regional Variations ◽  
Visual Areas ◽  
Monkey Visual Cortex

The distribution of orientation and wavelength selective cells in visual areas V1, the V4 complex and V5 of macaque monkey cortex was studied by recording from regions representing equivalent eccentricities in each and characterizing cells for their orientational and wavelength preferences. The results showed: ( a ) that in VI wavelength selective cells are concentrated in the region of foveal representation (central 0-2°) and decline at increasing eccentricities; ( b ) that in the V4 complex the concentration of such cells does not vary with eccentricity ; rather, there are regional variations that are not eccentricity dependent but follow other, and unknown, rules; ( c ) that in V5 there are virtually no wavelength selective cells even at central eccentricities; ( d ) that in VI fewer than 50 % of cells with receptive fields in the central 0-2° are orientation selective and that the proportion of such cells increases to reach a high of about 80% at eccentricities of between 10 and 30°; ( e ) that in the V4 complex and in V5 the concentration of orientation selective cells decreases at increasing eccentricities; ( f ) that very few wavelength selective cells in VI and in the V4 complex are orientation selective. The implications of these findings for a comparison between visual areas of the monkey cortex are discussed.

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