Area 17 lesions deactivate area MT in owl monkeys

AbstractThe middle temporal visual area, MT, is one of three major targets of the primary visual cortex, area 17, in primates. We assessed the contribution of area 17 connections to the responsiveness of area MT neurons to visual stimuli by first mapping the representation of the visual hemifield in MT of anesthetized owl monkeys with microelectrodes, ablating an electrophysiologically mapped part of area 17, and then immediately remapping MT. Before the lesions, neurons at recording sites throughout MT responded vigorously to moving slits of light and other visual stimuli. In addition, the relationship of receptive fields to recording sites revealed a systematic representation of the contralateral visual hemifield in MT, as reported previously for owl monkeys and other primates. The immediate effect of removing part of the retinotopic map in area 17 by gentle aspiration was to selectively deactivate the corresponding part of the visuotopic map in MT. Lesions of dorsomedial area 17 representing central and paracentral vision of the lower visual quadrant deactivated neurons in caudomedial MT formerly having receptive fields in the central and paracentral lower visual quadrant. Most neurons at recording sites throughout other parts of MT had normal levels of responsiveness to visual stimuli, and receptive-field locations that closely matched those before the lesion. However, neurons at a few sites along the margin of the deactivated zone of cortex had receptive fields that were slightly displaced from the region of vision affected by the lesion into other parts of the visual field, suggesting some degree of plasticity in the visual hemifield representation in MT. Subsequent histological examination of cortex confirmed that the lesions were confined to area 17 and the recordings were in MT. The results indicate that the visually evoked activity of neurons in MT of owl monkeys is highly dependent on inputs relayed directly or indirectly from area 17.

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

Journal of Neurophysiology ◽

10.1152/jn.00505.2005 ◽

2005 ◽

Vol 94 (6) ◽

pp. 4156-4167 ◽

Cited By ~ 14

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.

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Receptive-field properties of neurons in middle temporal visual area (MT) of owl monkeys

Journal of Neurophysiology ◽

10.1152/jn.1984.52.3.488 ◽

1984 ◽

Vol 52 (3) ◽

pp. 488-513 ◽

Cited By ~ 124

Author(s):

D. J. Felleman ◽

J. H. Kaas

Keyword(s):

Receptive Field ◽

Stimulus Onset ◽

Visual Area ◽

Area Mt ◽

Stimulus Movement ◽

Middle Temporal ◽

Preferred Direction ◽

Direction Of Movement ◽

Owl Monkeys ◽

Visual Area Mt

Response properties of single neurons in the middle temporal visual area (MT) of anesthetized owl monkeys were determined and quantified for flashed and moving bars of light under computer control for position, orientation, direction of movement, and speed. Receptive-field sizes, ranging from 4 to 25 degrees in width, were considerably larger than receptive fields with corresponding eccentricities in the striate cortex. Neurons were highly binocular with most cells equally or nearly equally activated by either eye. Neurons varied in selectivity for axis and direction of moving bars. Some neurons demonstrated little or no selectivity, others were bidirectional on a single axis, while the largest group was highly selective for direction with little or no response to bar movement opposite to the preferred direction. Over 70% of neurons were classified as highly selective and 90% showed some preference for direction and/or axis of stimulus movement. Neurons typically responded to bar movement only over a restricted range of velocities. The majority of neurons responded best to a particular velocity within the 5-60 degrees/s range, with marked attenuation of the response for velocities greater or less than the preferred. Some neurons failed to show significant response attenuation even at the lowest tested velocity, while other neurons preferred velocities of 100 degrees/s or more and failed to attenuate to the highest velocities. Response magnitude varied with stimulus dimensions. Increasing the length of the moving bar typically increased the magnitude of the response slightly until the stimulus exceeded the receptive-field borders. Other neurons responded less to increases in bar length within the excitatory receptive field. Neurons preferred narrow bars less than 1 degree in width, and marked reductions in responses characteristically occurred with wider stimuli. Moving patterns of randomly placed small dots were often as effective as or more effective than single bars in activating neurons. Selectivity for direction of movement remained for the dot pattern. for the dot pattern. Poststimulus time (PST) histograms of responses to bars flashed at a series of 21 different positions across the receptive field, in the "response-plane" format, indicated a spatially and temporally homogeneous receptive-field structure for nearly all neurons. Cells characteristically showed transient excitation at both stimulus onset and offset for all effective stimulus locations. Some cells responded mainly at bright stimulus onset or offset.

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

Perception ◽

10.1068/p140105 ◽

1985 ◽

Vol 14 (2) ◽

pp. 105-126 ◽

Cited By ~ 435

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.

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Response selectivity of neurons in area MT of the macaque monkey during reversible inactivation of area V1

Journal of Neurophysiology ◽

10.1152/jn.1992.67.6.1437 ◽

1992 ◽

Vol 67 (6) ◽

pp. 1437-1446 ◽

Cited By ~ 137

Author(s):

P. Girard ◽

P. A. Salin ◽

J. Bullier

Keyword(s):

Receptive Field ◽

Macaque Monkey ◽

Direction Selectivity ◽

Area 17 ◽

Visual Responses ◽

Area Mt ◽

Reversible Inactivation ◽

Mt Neurons ◽

Preferred Direction ◽

Blocking Index

1. Behavioral results in the monkey and clinical studies in human show remarkable residual visual capacities after a lesion of area V1. Earlier work by Rodman et al. demonstrated that visual activity can be recorded in the middle temporal area (MT) of the macaque monkey several weeks after a complete lesion of V1. These authors also tested the effect of a reversible block of area V1 on the visual responses of a small number of neurons in area MT and showed that most of these cells remain visually responsive. From the results of that study, however, it is difficult to assess the contribution of area 17 to the receptive-field selectivity of area MT neurons. To address this question, we have quantitatively measured the effects of a reversible inactivation of area 17 on the direction selectivity of MT neurons. 2. A circular part of the opercular region of area V1 was reversibly inactivated by cooling with a Peltier device. A microelectrode was positioned in the lower layers of V1 to control the total inactivation of that area. Eighty percent of the sites recorded in the retinotopically corresponding region of MT during inactivation of V1 were found to be visually responsive. The importance of the effect was assessed by calculating the blocking index (0 for no effect, 1 for complete inactivation). Approximately one-half of the quantitatively studied neurons gave a blocking index below 0.6, illustrating the strong residual responses recorded in many neurons. 3. Receptive-field properties were examined with multihistograms. It was found that, during inactivation of V1, the preferred direction changed for most neurons but remained close to the preferred direction or to its opposite in the control situation. During inactivation of V1, the average tuning curve of neurons became broader mostly because of strong reductions in the response to directions close to the preferred and nonpreferred. Very little change was observed in the responses for directions at 90 degrees to the optimal. These results are consistent with a model in which direction selectivity is present without an input from V1 but is reinforced by the spatial organization of this excitatory input. 4. Residual responses were found to be highly dependent on the state of anesthesia because they were completely abolished by the addition of 0.4-0.5% halothane to the ventilation gases. Finally, visual responses were recorded in area MT several hours after an acute lesion of area 17.(ABSTRACT TRUNCATED AT 400 WORDS)

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Spatial precision of population activity in primate area MT

Journal of Neurophysiology ◽

10.1152/jn.00152.2015 ◽

2015 ◽

Vol 114 (2) ◽

pp. 869-878 ◽

Cited By ~ 13

Author(s):

Spencer C. Chen ◽

John W. Morley ◽

Samuel G. Solomon

Keyword(s):

Neural Activity ◽

Visual Processing ◽

Receptive Fields ◽

Object Motion ◽

Spatial Position ◽

Multielectrode Arrays ◽

Visual World ◽

Population Activity ◽

Area Mt ◽

Mt Neurons

The middle temporal (MT) area is a cortical area integral to the “where” pathway of primate visual processing, signaling the movement and position of objects in the visual world. The receptive field of a single MT neuron is sensitive to the direction of object motion but is too large to signal precise spatial position. Here, we asked if the activity of MT neurons could be combined to support the high spatial precision required in the where pathway. With the use of multielectrode arrays, we recorded simultaneously neural activity at 24–65 sites in area MT of anesthetized marmoset monkeys. We found that although individual receptive fields span more than 5° of the visual field, the combined population response can support fine spatial discriminations (<0.2°). This is because receptive fields at neighboring sites overlapped substantially, and changes in spatial position are therefore projected onto neural activity in a large ensemble of neurons. This fine spatial discrimination is supported primarily by neurons with receptive fields flanking the target locations. Population performance is degraded (by 13–22%) when correlations in neural activity are ignored, further reflecting the contribution of population neural interactions. Our results show that population signals can provide high spatial precision despite large receptive fields, allowing area MT to represent both the motion and the position of objects in the visual world.

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Feature attention for binocular disparity in primate area MT depends on tuning strength

Journal of Neurophysiology ◽

10.1152/jn.00772.2014 ◽

2015 ◽

Vol 113 (5) ◽

pp. 1545-1555 ◽

Cited By ~ 6

Author(s):

Douglas A. Ruff ◽

Richard T. Born

Keyword(s):

Binocular Disparity ◽

Receptive Fields ◽

Sensory Information ◽

Neuronal Population ◽

Area Mt ◽

Temporal Area ◽

Mt Neurons ◽

Feature Attention ◽

The Difference ◽

The Relationship

Attending to a stimulus modulates the responses of sensory neurons that represent features of that stimulus, a phenomenon named “feature attention.” For example, attending to a stimulus containing upward motion enhances the responses of upward-preferring direction-selective neurons in the middle temporal area (MT) and suppresses the responses of downward-preferring neurons, even when the attended stimulus is outside of the spatial receptive fields of the recorded neurons (Treue S, Martinez-Trujillo JC. Nature 399: 575–579, 1999). This modulation renders the representation of sensory information across a neuronal population more selective for the features present in the attended stimulus (Martinez-Trujillo JC, Treue S. Curr Biol 14: 744–751, 2004). We hypothesized that if feature attention modulates neurons according to their tuning preferences, it should also be sensitive to their tuning strength, which is the magnitude of the difference in responses to preferred and null stimuli. We measured how the effects of feature attention on MT neurons in rhesus monkeys ( Macaca mulatta) depended on the relationship between features—in our case, direction of motion and binocular disparity—of the attended stimulus and a neuron's tuning for those features. We found that, as for direction, attention to stimuli containing binocular disparity cues modulated the responses of MT neurons and that the magnitude of the modulation depended on both a neuron's tuning preferences and its tuning strength. Our results suggest that modulation by feature attention may depend not just on which features a neuron represents but also on how well the neuron represents those features.

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Functional Organization of Speed Tuned Neurons in Visual Area MT

Journal of Neurophysiology ◽

10.1152/jn.00097.2002 ◽

2003 ◽

Vol 89 (1) ◽

pp. 246-256 ◽

Cited By ~ 53

Author(s):

Jing Liu ◽

William T. Newsome

Keyword(s):

Functional Organization ◽

Rate Of Change ◽

Visual Area ◽

Cortical Surface ◽

Data Set ◽

Area Mt ◽

Mt Neurons ◽

Preferred Direction ◽

Columnar Organization ◽

Visual Area Mt

We analyzed the functional organization of speed tuned neurons in extrastriate visual area MT. We sought to determine whether neurons tuned for particular speeds are clustered spatially and whether such spatial clusters are elongated normal to the cortical surface so as to form speed columns. Our data showed that MT neurons are indeed clustered according to preferred speed. Multiunit recordings were speed tuned, and the speed tuning of these signals was well correlated with the speed tuning of single neurons recorded simultaneously. To determine whether speed columns exist in MT, we compared the rates at which preferred speed changed in electrode tracks that traversed MT obliquely and normally to the cortical surface. If speed columns exist, the preferred speed should change at a faster rate during oblique electrode tracks. We found, however, that preferred speed changed at similar rates for either type of penetration. In the same data set, the rate of change of preferred direction and preferred disparity differed substantially in normal and oblique penetrations as expected from the known columnar organization of MT. Thus our results suggest that a columnar organization for speed tuned neurons does not exist in MT.

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Encoding of dynamic visual stimuli by primate area MT neurons

Neurocomputing ◽

10.1016/j.neucom.2004.10.066 ◽

2005 ◽

Vol 65-66 ◽

pp. 135-142 ◽

Cited By ~ 1

Author(s):

Heiko Stemmann ◽

Winrich A. Freiwald ◽

Aurel Wannig ◽

Erich L. Schulzke ◽

Christian W. Eurich

Keyword(s):

Visual Stimuli ◽

Area Mt ◽

Mt Neurons

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

Visual Neuroscience ◽

10.1017/s0952523800012037 ◽

1989 ◽

Vol 2 (2) ◽

pp. 177-188 ◽

Cited By ~ 83

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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