Activity of Neurons in Cortical Area MT During a Memory for Motion Task

2004 ◽  
Vol 91 (1) ◽  
pp. 286-300 ◽  
Author(s):  
James W. Bisley ◽  
Daniel Zaksas ◽  
Jason A. Droll ◽  
Tatiana Pasternak
Keyword(s):  
Visual Motion ◽  
Sample Stimulus ◽  
Subsequent Increase ◽  
Middle Temporal ◽  
Firing Rates ◽  
Mt Neurons ◽  
Gating Mechanism ◽  
Successful Execution ◽  
Task Irrelevant ◽  
Related Process

We recorded the activity of middle temporal (MT) neurons in 2 monkeys while they compared the directions of motion in 2 sequentially presented random-dot stimuli, sample and test, and reported them as the same or different by pressing one of 2 buttons. We found that MT neurons were active not only in response to the sample and test stimuli but also during the 1,500-ms delay separating them. Most neurons showed a characteristic pattern of activity consisting of a small burst of firing early in the delay, followed by a period of suppression and a subsequent increase in firing rate immediately preceding the presentation of the test stimulus. In a third of the neurons, the activity early in the delay not only reflected the direction of the sample stimulus, but was also related to the range of local directions it contained. During the middle of the delay the majority of neurons were suppressed, consistent with a gating mechanism that could be used to ignore task-irrelevant stimuli. Late in the delay, most neurons showed an increase in response, probably in anticipation of the upcoming test. Throughout most of the delay there was a directional signal in the population of MT neurons, manifested by higher firing rates following the sample moving in the antipreferred direction. Whereas some of these effects may be related to sensory adaptation, others are more likely to represent a more active task-related process. These results support the hypothesis that MT neurons actively participate in the successful execution of all aspects of the task requiring processing and remembering visual motion.

Visual impairment by surrounding noise is due to interactions among stimuli in the higher-order visual cortex

2014 ◽  
Vol 112 (3) ◽  
pp. 620-630
Author(s):  
Hironori Kumano ◽  
Takanori Uka
Keyword(s):  
Visual Cortex ◽  
Peripheral Vision ◽  
Higher Order ◽  
Visual Neurons ◽  
Middle Temporal ◽  
Mt Neurons ◽  
Impaired Ability ◽  
Psychophysical Threshold ◽  
Task Irrelevant ◽  
Visual Area Mt

Observers have difficulty identifying a target in their peripheral vision in the presence of surrounding stimuli. Although hypotheses addressing this phenomenon have been proposed, such as the integration of stimuli and surround suppression in the higher-order visual cortex, no direct comparisons of the psychophysical and neuronal sensitivities have been performed. Here we measured the performance of monkeys with a variant of the direction discrimination task using a center/surround bipartite random-dot stimulus while simultaneously recording from isolated neurons from the middle temporal visual area (MT). The psychophysical threshold increased with the addition of a task-irrelevant noise annulus that surrounded the task-relevant motion stimuli. The neuronal threshold of MT neurons also increased at a spatial scale similar to the psychophysical threshold. This suggests that the impaired ability in our task resulted from impairment in the MT area. Importantly, reduced neuronal performance was due to both a reduced response to preferred motion and an enhanced response to nonpreferred motion. These observations suggest that impairment caused by surrounding noise results from interactions between stimuli and noise and not from a reduction in the response of visual neurons.

Area MT Neurons Respond to Visual Motion Distant From Their Receptive Fields

2005 ◽  
Vol 94 (6) ◽  
pp. 4156-4167 ◽  
Author(s):  
Daniel Zaksas ◽  
Tatiana Pasternak
Keyword(s):  
Time Course ◽  
Visual Motion ◽  
Cognitive Task ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Task Demands ◽  
Visual Signals ◽  
Area Mt ◽  
Mt Neurons ◽  
Stimulus Offset

Neurons in cortical area MT have localized receptive fields (RF) representing the contralateral hemifield and play an important role in processing visual motion. We recorded the activity of these neurons during a behavioral task in which two monkeys were required to discriminate and remember visual motion presented in the ipsilateral hemifield. During the task, the monkeys viewed two stimuli, sample and test, separated by a brief delay and reported whether they contained motion in the same or in opposite directions. Fifty to 70% of MT neurons were activated by the motion stimuli presented in the ipsilateral hemifield at locations far removed from their classical receptive fields. These responses were in the form of excitation or suppression and were delayed relative to conventional MT responses. Both excitatory and suppressive responses were direction selective, but the nature and the time course of their directionality differed from the conventional excitatory responses recorded with stimuli in the RF. Direction selectivity of the excitatory remote response was transient and early, whereas the suppressive response developed later and persisted after stimulus offset. The presence or absence of these unusual responses on error trials, as well as their magnitude, was affected by the behavioral significance of stimuli used in the task. We hypothesize that these responses represent top-down signals from brain region(s) accessing information about stimuli in the entire visual field and about the behavioral state of the animal. The recruitment of neurons in the opposite hemisphere during processing of behaviorally relevant visual signals reveals a mechanism by which sensory processing can be affected by cognitive task demands.

scholarly journals Sensitivity of Neurons in the Middle Temporal Area of Marmoset Monkeys to Random Dot Motion

2017 ◽  
Author(s):  
Tristan A. Chaplin ◽  
Benjamin J. Allitt ◽  
Maureen A. Hagan ◽  
Nicholas S. Price ◽  
Ramesh Rajan ◽  
...  
Keyword(s):  
Primate Species ◽  
Neural Basis ◽  
Temporal Area ◽  
Middle Temporal ◽  
Mt Neurons ◽  
Wide Range ◽  
Middle Temporal Area ◽  
Dot Motion ◽  
Marmoset Monkeys ◽  
Random Dot Motion

AbstractNeurons in the Middle Temporal area (MT) of the primate cerebral cortex respond to moving visual stimuli. The sensitivity of MT neurons to motion signals can be characterized by using random-dot stimuli, in which the strength of the motion signal is manipulated by adding different levels of noise (elements that move in random directions). In macaques, this has allowed the calculation of “neurometric” thresholds. We characterized the responses of MT neurons in sufentanil/nitrous oxide anesthetized marmoset monkeys, a species which has attracted considerable recent interest as an animal model for vision research. We found that MT neurons show a wide range of neurometric thresholds, and that the responses of the most sensitive neurons could account for the behavioral performance of macaques and humans. We also investigated factors that contributed to the wide range of observed thresholds. The difference in firing rate between responses to motion in the preferred and null directions was the most effective predictor of neurometric threshold, whereas the direction tuning bandwidth had no correlation with the threshold. We also showed that it is possible to obtain reliable estimates of neurometric thresholds using stimuli that were not highly optimized for each neuron, as is often necessary when recording from large populations of neurons with different receptive field concurrently, as was the case in this study. These results demonstrate that marmoset MT shows an essential physiological similarity to macaque MT, and suggest that its neurons are capable of representing motion signals that allow for comparable motion-in-noise judgments.New and NoteworthyWe report the activity of neurons in marmoset MT in response to random-dot motion stimuli of varying coherence. The information carried by individual MT neurons was comparable to that of the macaque, and that the maximum firing rates were a strong predictor of sensitivity. Our study provides key information regarding the neural basis of motion perception in the marmoset, a small primate species that is becoming increasingly popular as an experimental model.

scholarly journals Inactivation of lateral prefrontal cortex increases activity of MT neurons during memory-guided comparisons of visual motion

2017 ◽  
Vol 17 (10) ◽  
pp. 930
Author(s):  
David Samu ◽  
Ruben Moreno-Bote ◽  
Albert Compte ◽  
Tatiana Pasternak
Keyword(s):  
Prefrontal Cortex ◽  
Visual Motion ◽  
Lateral Prefrontal Cortex ◽  
Mt Neurons

Direction- and Velocity-Specific Responses from beyond the Classical Receptive Field in the Middle Temporal Visual Area (MT)

Perception ◽  
1985 ◽  
Vol 14 (2) ◽  
pp. 105-126 ◽  
Author(s):  
John Allman ◽  
Francis Miezin ◽  
EveLynn McGuinness
Keyword(s):  
Receptive Field ◽  
Visual Area ◽  
Area Mt ◽  
Motion Cues ◽  
Middle Temporal ◽  
Global Context ◽  
Mt Neurons ◽  
Classical Receptive Field ◽  
Local Stimulus ◽  
Visual Area Mt

The true receptive field of more than 90% of neurons in the middle temporal visual area (MT) extends well beyond the classical receptive field (crf), as mapped with conventional bar or spot stimuli, and includes a surrounding region that is 50 to 100 times the area of the crf. These extensive surrounds are demonstrated by simultaneously stimulating the crf and the surround with moving stimuli. The surrounds commonly have directional and velocity-selective influences that are antagonistic to the response from the crf. The crfs of MT neurons are organized in a topographic representation of the visual field. Thus MT neurons are embedded in an orderly visuotopic array, but are capable of integrating local stimulus conditions within a global context. The extensive surrounds of MT neurons may be involved in figure–ground discrimination, preattentive vision, perceptual constancies, and depth perception through motion cues.

scholarly journals The fate of task-irrelevant visual motion: Perceptual load versus feature-based attention

2009 ◽  
Vol 9 (12) ◽  
pp. 12-12 ◽  
Author(s):  
S. Taya ◽  
W. J. Adams ◽  
E. W. Graf ◽  
N. Lavie
Keyword(s):  
Visual Motion ◽  
Perceptual Load ◽  
Feature Based ◽  
Task Irrelevant

The direct, not V1-mediated, functional influence between the thalamus and middle temporal complex in the human brain is modulated by the speed of visual motion

Neuroscience ◽  
2015 ◽  
Vol 284 ◽  
pp. 833-844 ◽  
Author(s):  
A. Gaglianese ◽  
M. Costagli ◽  
K. Ueno ◽  
E. Ricciardi ◽  
G. Bernardi ◽  
...  
Keyword(s):  
Human Brain ◽  
Visual Motion ◽  
Middle Temporal

scholarly journals Task-irrelevant visual motion and flicker attenuate the attentional blink

2006 ◽  
Vol 13 (4) ◽  
pp. 600-607 ◽  
Author(s):  
Isabel Arend ◽  
Stephen Johnston ◽  
Kimron Shapiro
Keyword(s):  
Attentional Blink ◽  
Visual Motion ◽  
Task Irrelevant

scholarly journals MT Neurons Combine Visual Motion with a Smooth Eye Movement Signal to Code Depth-Sign from Motion Parallax

Neuron ◽  
2009 ◽  
Vol 63 (4) ◽  
pp. 523-532 ◽  
Author(s):  
Jacob W. Nadler ◽  
Mark Nawrot ◽  
Dora E. Angelaki ◽  
Gregory C. DeAngelis
Keyword(s):  
Eye Movement ◽  
Visual Motion ◽  
Motion Parallax ◽  
Mt Neurons
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