scholarly journals Visual Functions of Primate Area V4

2020 ◽  
Vol 6 (1) ◽  
pp. 363-385 ◽  
Author(s):  
Anitha Pasupathy ◽  
Dina V. Popovkina ◽  
Taekjun Kim
Keyword(s):  
Macaque Monkey ◽  
High Dimensional ◽  
Functional Domain ◽  
Subcortical Structures ◽  
Area V4 ◽  
Cortical Areas ◽  
Neurophysiological Studies ◽  
Ventral Pathway ◽  
Visual Cortical ◽  
Color Depth

Area V4—the focus of this review—is a mid-level processing stage along the ventral visual pathway of the macaque monkey. V4 is extensively interconnected with other visual cortical areas along the ventral and dorsal visual streams, with frontal cortical areas, and with several subcortical structures. Thus, it is well poised to play a broad and integrative role in visual perception and recognition—the functional domain of the ventral pathway. Neurophysiological studies in monkeys engaged in passive fixation and behavioral tasks suggest that V4 responses are dictated by tuning in a high-dimensional stimulus space defined by form, texture, color, depth, and other attributes of visual stimuli. This high-dimensional tuning may underlie the development of object-based representations in the visual cortex that are critical for tracking, recognizing, and interacting with objects. Neurophysiological and lesion studies also suggest that V4 responses are important for guiding perceptual decisions and higher-order behavior.

Subcortical structures projecting to visual cortical areas in squirrel monkey

1982 ◽  
Vol 209 (1) ◽  
pp. 29-40 ◽  
Author(s):  
Johannes Tigges ◽  
M. Tigges ◽  
N. A. Cross ◽  
R. L. McBride ◽  
W. D. Letbetter ◽  
...  
Keyword(s):  
Squirrel Monkey ◽  
Subcortical Structures ◽  
Cortical Areas ◽  
Visual Cortical

scholarly journals Routing information flow by separate neural synchrony frequencies allows for “functionally labeled lines” in higher primate cortex

2019 ◽  
Vol 116 (25) ◽  
pp. 12506-12515 ◽  
Author(s):  
Mohammad Bagher Khamechian ◽  
Vladislav Kozyrev ◽  
Stefan Treue ◽  
Moein Esghaei ◽  
Mohammad Reza Daliri
Keyword(s):  
Information Flow ◽  
Information Transfer ◽  
Sensory Information ◽  
Spike Timing ◽  
Oscillatory Activity ◽  
Attention Task ◽  
Cortical Areas ◽  
High Gamma ◽  
Ventral Pathway ◽  
Visual Cortical

Efficient transfer of sensory information to higher (motor or associative) areas in primate visual cortical areas is crucial for transforming sensory input into behavioral actions. Dynamically increasing the level of coordination between single neurons has been suggested as an important contributor to this efficiency. We propose that differences between the functional coordination in different visual pathways might be used to unambiguously identify the source of input to the higher areas, ensuring a proper routing of the information flow. Here we determined the level of coordination between neurons in area MT in macaque visual cortex in a visual attention task via the strength of synchronization between the neurons’ spike timing relative to the phase of oscillatory activities in local field potentials. In contrast to reports on the ventral visual pathway, we observed the synchrony of spikes only in the range of high gamma (180 to 220 Hz), rather than gamma (40 to 70 Hz) (as reported previously) to predict the animal’s reaction speed. This supports a mechanistic role of the phase of high-gamma oscillatory activity in dynamically modulating the efficiency of neuronal information transfer. In addition, for inputs to higher cortical areas converging from the dorsal and ventral pathway, the distinct frequency bands of these inputs can be leveraged to preserve the identity of the input source. In this way source-specific oscillatory activity in primate cortex can serve to establish and maintain “functionally labeled lines” for dynamically adjusting cortical information transfer and multiplexing converging sensory signals.

Comparison of neuronal selectivity for stimulus speed, length, and contrast in the prestriate visual cortical areas V4 and MT of the macaque monkey

1994 ◽  
Vol 71 (6) ◽  
pp. 2269-2280 ◽  
Author(s):  
K. Cheng ◽  
T. Hasegawa ◽  
K. S. Saleem ◽  
K. Tanaka
Keyword(s):  
Receptive Field ◽  
Luminance Contrast ◽  
Macaque Monkey ◽  
Stimulus Motion ◽  
Temporal Area ◽  
Area V4 ◽  
Optimal Speed ◽  
Stimulus Speed ◽  
Stimulus Length ◽  
Visual Cortical

1. Prestriate area V4 and the middle temporal area (MT) compose the first stage in which the ventral and dorsal visual cortical pathways are segregated. To better known the functional dichotomy between the two pathways at this level, we recorded cell responses from V4 and MT using anesthetized, immobilized macaque monkeys and compared the selectivity for speed of stimulus motion and stimulus length and the sensitivity to luminance contrast between the two areas. 2. V4 cells were as selective as MT cells for speed. The sharpness of tuning was not different between the two populations. The optimal speed varied widely in both areas, but both of the two distributions showed peaks at 32 degrees/s. 3. V4 and MT cells were similar in that about one-half of the cells (45% in V4 and 48% in MT) showed inhibition by long (16 degrees) bars. However, V4 cells preferred stimuli whose lengths were distributed around the lengths of the receptive field, whereas an overwhelming majority of MT cells preferred stimuli whose lengths were much shorter than the lengths of the receptive field. 4. The cutoff contrast at which one-half the maximum response was elicited was distributed widely in both areas, and the two distributions considerably overlapped. MT cells as a whole, however, were slightly more sensitive to the luminance contrast than V4 cells. 5. There was a tendency toward local clustering for cells with similar speed preferences in MT but not in V4. Pairs of MT cells recorded within 400 microns had smaller difference in the optimal speed than that of cell pairs taken randomly from the whole sample of MT cells.

Extraretinal representations in area V4 in the macaque monkey

1991 ◽  
Vol 7 (6) ◽  
pp. 561-573 ◽  
Author(s):  
John H. R. Maunsell ◽  
Gary Sclar ◽  
Tara A. Nealey ◽  
Derryl D. DePriest
Keyword(s):  
Macaque Monkey ◽  
Matching Task ◽  
Systematic Change ◽  
Visual Responses ◽  
Match To Sample ◽  
Area V4 ◽  
Neurophysiological Studies ◽  
Sample Orientation ◽  
Fixation Task ◽  
Simple Fixation

AbstractSeveral neurophysiological studies have shown that the visual cerebral cortex of macaque monkeys performing delayed match-to-sample tasks contains individual neurons whose levels of activity depend on the sample the animal is required to remember. Haenny et al. (1988) reported that the activity of neurons in area V4 of monkeys performing an orientation matching task depends on the orientation for which the animal is searching. It was proposed that these neurons contribute to a representation of the orientation being sought.We have further characterized these neurons by recording visual responses from individual neurons during multiple behavioral tasks. Animals were trained to perform an orientation match-to-sample task using either a visual or a tactile orientation sample. In a set of 89 neurons examined using both types of sample, 25% showed statistically significant effects of sample orientation regardless of whether the sample was visual or tactile. Most of these preferred the same sample orientation in both conditions. These results allow us to specify the nature of the information signaled by these neurons more precisely than has previously been possible.For 193 units tested using one of the matching tasks, responses were also recorded while the animal performed a simple fixation task. In this task the animal was not required to attend to the visual stimuli that were presented. A few neurons that were responsive during the matching task were silent during fixation, but a comparable number was much more responsive during fixation. Across the whole population there was no systematic change in either responsivity or selectivity for orientation under the two conditions.

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.

Sign in / Sign up

Export Citation Format

Share Document