scholarly journals Distracter suppression dominates attentional modulation of responses to multiple stimuli inside the receptive fields of middle temporal neurons

2017 ◽  
Vol 46 (12) ◽  
pp. 2844-2858 ◽  
Author(s):  
Nour Malek ◽  
Stefan Treue ◽  
Paul Khayat ◽  
Julio Martinez‐Trujillo
Keyword(s):  
Receptive Fields ◽  
Attentional Modulation ◽  
Middle Temporal

scholarly journals The Effect of Attention on Neuronal Responses to High and Low Contrast Stimuli

2010 ◽  
Vol 104 (2) ◽  
pp. 960-971 ◽  
Author(s):  
Joonyeol Lee ◽  
John H. R. Maunsell
Keyword(s):  
Cerebral Cortex ◽  
Visual Cortex ◽  
Rhesus Monkeys ◽  
Receptive Fields ◽  
Visual Area ◽  
Neuronal Responses ◽  
Attentional Modulation ◽  
Low Contrast ◽  
Middle Temporal ◽  
Visual Area Mt

It remains unclear how attention affects the tuning of individual neurons in visual cerebral cortex. Some observations suggest that attention preferentially enhances responses to low contrast stimuli, whereas others suggest that attention proportionally affects responses to all stimuli. Resolving how attention affects responses to different stimuli is essential for understanding the mechanism by which it acts. To explore the effects of attention on stimuli of different contrasts, we recorded from individual neurons in the middle temporal visual area (MT) of rhesus monkeys while shifting their attention between preferred and nonpreferred stimuli within their receptive fields. This configuration results in robust attentional modulation that makes it possible to readily distinguish whether attention acts preferentially on low contrast stimuli. We found no evidence for greater enhancement of low contrast stimuli. Instead, the strong attentional modulations were well explained by a model in which attention proportionally enhances responses to stimuli of all contrasts. These data, together with observations on the effects of attention on responses to other stimulus dimensions, suggest that the primary effect of attention in visual cortex may be to simply increase the strength of responses to all stimuli by the same proportion.

Visual response properties of neurons in four extrastriate visual areas of the owl monkey (Aotus trivirgatus): a quantitative comparison of medial, dorsomedial, dorsolateral, and middle temporal areas

1981 ◽  
Vol 45 (3) ◽  
pp. 397-416 ◽  
Author(s):  
J. F. Baker ◽  
S. E. Petersen ◽  
W. T. Newsome ◽  
J. M. Allman
Keyword(s):  
Receptive Fields ◽  
Field Size ◽  
Visual Response ◽  
Response Properties ◽  
Middle Temporal ◽  
Optimal Direction ◽  
Visual Areas ◽  
Direction Of Movement ◽  
Owl Monkeys ◽  
The Difference

1. The response properties of 354 single neurons in the medial (M), dorsomedial (DM), dorsolateral (DL), and middle temporal (MT) visual areas were studied quantitatively with bar, spot, and random-dot stimuli in chronically implanted owl monkeys with fixed gaze. 2. A directionality index was computed to compare the responses to stimuli in the optimal direction with the responses to the opposing direction of movement. The greater the difference between opposing directions, the higher the index. MT cells had much higher direction indices to moving bars than cells in DL, DM, and M. 3. A tuning index was computed for each cell to compare the responses to bars moving in the optimal direction, or flashed in the optimal orientation, with the responses in other directions or orientations within +/- 90 degrees. Cells in all four areas were more sharply tuned to the orientation of stationary flashed bars than to moving bars, although a few cells (9/92( were unresponsive in the absence of movement. DM cells tended to be more sharply tuned to moving bars than cells in the other areas. 4. Directionality in DM, DL, and MT was relatively unaffected by the use of single-spot stimuli instead of bars; tuning in all four areas was broader to spots than bars. 5. Moving arrays of randomly spaced spots were more strongly excitatory than bar stimuli for many neurons in MT (16/31 cells). These random-dot stimuli were also effective in M, but evoked no response or weak responses from most cells in DM and DL. 6. The best velocities of movement were usually in the range of 10-100 degrees/s, although a few cells (22/227), primarily in MT (14/69 cells), preferred higher velocities. 7. Receptive fields of neurons in all four areas were much larger than striate receptive fields. Eccentricity was positively correlated with receptive-field size (r = 0.62), but was not correlated with directionality index, tuning index, or best velocity. 8. The results support the hypothesis that there are specializations of function among the cortical visual areas.

scholarly journals Biologically inspired computational modeling of motion based on middle temporal area

2018 ◽  
Vol 9 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Fernanda da C. e C. Faria ◽  
Jorge Batista ◽  
Helder Araújo
Keyword(s):  
Receptive Fields ◽  
Biologically Inspired ◽  
Significant Information ◽  
Temporal Area ◽  
Middle Temporal ◽  
Complex Cells ◽  
Motion Computation ◽  
Reciprocal Connections ◽  
Middle Temporal Area ◽  
Last Stage

Abstract This paper describes a bio-inspired algorithm for motion computation based on V1 (Primary Visual Cortex) andMT (Middle Temporal Area) cells. The behavior of neurons in V1 and MT areas contain significant information to understand the perception of motion. From a computational perspective, the neurons are treated as two dimensional filters to represent the receptive fields of simple cells that compose the complex cells. A modified elaborated Reichardt detector, adding an output exponent before the last stage followed by a re-entry stage of modulating feedback from MT, (reciprocal connections of V1 and MT) in a hierarchical framework, is proposed. The endstopped units, where the receptive fields of cells are surrounded by suppressive regions, are modeled as a divisive operation. MT cells play an important role for integrating and interpreting inputs from earlier-level (V1).We fit a normalization and a pooling to find the most active neurons for motion detection. All steps employed are physiologically inspired processing schemes and need some degree of simplification and abstraction. The results suggest that our proposed algorithm can achieve better performance than recent state-of-the-art bio-inspired approaches for real world images.

Center-Surround Interactions in the Middle Temporal Visual Area of the Owl Monkey

2000 ◽  
Vol 84 (5) ◽  
pp. 2658-2669 ◽  
Author(s):  
Richard T. Born
Keyword(s):  
Visual Motion ◽  
Receptive Fields ◽  
Visual Area ◽  
Motion Processing ◽  
Wide Field ◽  
Local Motion ◽  
Middle Temporal ◽  
Visual Motion Processing ◽  
Owl Monkey ◽  
Motion Contrast

Microelectrode recording and 2-deoxyglucose (2dg) labeling were used to investigate center-surround interactions in the middle temporal visual area (MT) of the owl monkey. These techniques revealed columnar groups of neurons whose receptive fields had opposite types of center-surround interaction with respect to moving visual stimuli. In one type of column, neurons responded well to objects such as a single bar or spot but poorly to large textured stimuli such as random dots. This was often due to the fact that the receptive fields had antagonistic surrounds: surround motion in the same direction as that preferred by the center suppressed responses, thus rendering these neurons unresponsive to wide-field motion. In the second set of complementary, interdigitated columns, neuronal receptive fields had reinforcing surrounds and responded optimally to wide-field motion. This functional organization could not be accounted for by systematic differences in binocular disparity. Within both column types, neurons whose receptive fields exhibited center-surround interactions were found less frequently in the input layers compared with the other layers. Additional tests were done on single units to examine the nature of the center-surround interactions. The direction tuning of the surround was broader than that of the center, and the preferred direction, with respect to that of the center, tended to be either in the same or opposite direction and only rarely in orthogonal directions. Surround motion at various velocities modulated the overall responsiveness to centrally placed moving stimuli, but it did not produce shifts in the peaks of the center's tuning curves for either direction or speed. In layers 3B and 5 of the local motion processing columns, a number of neurons responded only to local motion contrast but did so over a region of the visual field that was much larger than the optimal stimulus size. The central feature of this receptive field type was the generalization of surround antagonism over retinotopic space—a property similar to other “complex” receptive fields described previously. The columnar organization of different types of center-surround interactions may reflect the initial segregation of visual motion information into wide-field and local motion contrast systems that serve complementary functions in visual motion processing. Such segregation appears to occur at later stages of the macaque motion processing stream, in the medial superior temporal area (MST), and has also been described in invertebrate visual systems where it appears to be involved in the important function of distinguishing background motion from object motion.

Centrifugal directional bias in the middle temporal visual area (MT) of the macaque

1989 ◽  
Vol 2 (2) ◽  
pp. 177-188 ◽  
Author(s):  
Thomas D. Albright
Keyword(s):  
Visual Stimulation ◽  
Receptive Fields ◽  
Visual Area ◽  
Area Mt ◽  
Directional Bias ◽  
Middle Temporal ◽  
Naturally Occurring ◽  
Forward Locomotion ◽  
Visual Area Mt ◽  
Biased Distribution

AbstractWe have examined the distribution of preferred directions of motion for neurons in the middle temporal visual area (MT) of the macaque. We found a marked anisotropy favoring directions that are oriented away from the center of gaze. This anisotropy is present only among neurons with peripherally located receptive fields. This peripheral centrifugal directionality bias corresponds well to the biased distribution of motions characteristic of optic flow fields, which are generated by displacement of the visual world during forward locomotion. The bias may facilitate the processing of this common form of visual stimulation and could underlie previously observed perceptual anisotropies favoring centrifugal motion. We suggest that the bias could arise from exposure of modifiable cortical circuitry to a naturally occurring form of selective visual experience.

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