Distinct Nature of Directional Signals Among Parietal Cortical Areas During Visual Guidance

2002 ◽  
Vol 88 (4) ◽  
pp. 1777-1790 ◽  
Author(s):  
Emad N. Eskandar ◽  
John A. Assad
Keyword(s):  
Visual Motion ◽  
Hand Movement ◽  
Direction Selectivity ◽  
Visually Guided ◽  
Stimulus Motion ◽  
Directional Information ◽  
Temporal Area ◽  
Medial Superior Temporal ◽  
Direction Of Movement ◽  
Mst Neurons

We examined neuronal signals in the monkey medial superior temporal area (MST), the medial intraparietal area (MIP), and the lateral intraparietal area (LIP) during visually guided hand movements. Two animals were trained to use a joystick to guide a spot to a target. Many neurons responded in a direction-selective manner in this guidance task. We tested whether the direction selectivity depended on the direction of the stimulus spot or the direction of the hand movement. First, in some trials, the moving spot disappeared transiently. Second, the mapping between the hand direction and the spot direction was reversed on alternate blocks of trials. Third, we recorded the spot's movement while the animals moved the joystick and then played back that movement while the animals fixated without moving the joystick. Neurons in the three parietal areas conveyed distinct directional information. MST neurons were active and directional only on visible trials in both joystick-movement mode and playback mode and were not affected by the direction of hand movement. MIP neurons were mainly directional with respect to the hand movement, although some MIP neurons were also selective for stimulus direction. MIP neurons were much less active in playback mode. LIP neurons were active and directional in both joystick-movement mode and playback mode. Directional signals in LIP were unrelated to planning saccades. The selectivity of LIP neurons also became evident hundreds of milliseconds before the start of movement. Since the direction of movement was consistent throughout a block of trials, these signals could provide a prediction of the upcoming direction of motion. We tested this by alternating blocks of trials in which the direction was consistent or randomized. The direction selectivity developed earlier on trials in which the upcoming direction could be predicted. These results suggest that LIP neurons combine “bottom-up” visual motion signals with extraretinal, predictive signals about stimulus motion.

Microstimulation of Cortical Area MT Affects Performance on a Visual Working Memory Task

2001 ◽  
Vol 85 (1) ◽  
pp. 187-196 ◽  
Author(s):  
James W. Bisley ◽  
Daniel Zaksas ◽  
Tatiana Pasternak
Keyword(s):  
Working Memory ◽  
Visual Motion ◽  
Memory Task ◽  
Stimulus Motion ◽  
Area Mt ◽  
Directional Information ◽  
Temporal Area ◽  
Mt Neurons ◽  
Directional Motion ◽  
Term Storage

We applied electrical stimulation to physiologically identified sites in macaque middle temporal area (MT) to examine its role in short-term storage of recently encoded information about stimulus motion. We used a behavioral task in which monkeys compared the directions of two moving random-dot stimuli, sample and test, separated by a 1.5-s delay. Four sample directions were used for each site, and the animals had to indicate whether the direction of motion in the sample was the same as or different to the direction of motion in the test. We found that the effect of stimulation of the same directional column in MT depended on the behavioral state of the animal. Although stimulation had strong effects when applied during the encoding and the storage components of the task, these effects were not equivalent. Stimulation applied during the presentation of the sample produced signals interpreted by the monkeys as directional motion. However, the same stimulation introduced during the period of storage no longer produced signals interpreted as unambiguous directional information. We conclude that the directional information used by the monkeys in the working memory task is likely to be provided by neurons in MT, and the use of this information appears to be dependent on the portion of the task during which stimulation was delivered. Finally, the disruptive effects of stimulation during the delay suggest that MT neurons not only participate in the encoding of visual motion information but also in its storage by either maintaining an active connection with the circuitry involved in storage or being an integral component of that circuitry.

MST Neurons Respond to Optic Flow and Translational Movement

1998 ◽  
Vol 80 (4) ◽  
pp. 1816-1827 ◽  
Author(s):  
Charles J. Duffy
Keyword(s):  
Optic Flow ◽  
Direction Selectivity ◽  
Movement Detection ◽  
Temporal Area ◽  
Medial Superior Temporal ◽  
Preferred Direction ◽  
Translational Movement ◽  
Mst Neurons ◽  
Best Responses ◽  
Stimulus Direction

Duffy, Charles J. MST neurons respond to optic flow and translational movement . J. Neurophysiol. 80: 1816–1827, 1998. We recorded the responses of 189 medial superior temporal area (MST) neurons by using optic flow, real translational movement, and combined stimuli in which matching directions of optic flow and real translational movement were presented together. One-half of the neurons (48%) showed strong responses to optic flow simulating self-movement in the horizontal plane, and 24% showed strong responses to translational movement. Combining optic flow stimuli with matching directions of translational movement caused substantial changes in both the amplitude of the best responses (44% of neurons) and the strength of direction selectivity (71% of neurons), with little effect on which stimulus direction was preferred. However, combining optic flow and translational movement such that opposite directions were presented together changed the preferred direction in 45% of the neurons with substantial changes in the strength of direction selectivity. These studies suggest that MST neurons combine visual and vestibular signals to enhance self-movement detection and disambiguate optic flow that results from either self-movement or the movement of large objects near the observer.

Sensitivity of MST neurons to optic flow stimuli. I. A continuum of response selectivity to large-field stimuli

1991 ◽  
Vol 65 (6) ◽  
pp. 1329-1345 ◽  
Author(s):  
C. J. Duffy ◽  
R. H. Wurtz
Keyword(s):  
Optic Flow ◽  
Receptive Fields ◽  
Flow Fields ◽  
Direction Selectivity ◽  
Single Component ◽  
Large Field ◽  
Temporal Area ◽  
Response Characteristics ◽  
Medial Superior Temporal ◽  
Mst Neurons

1. Neurons in the dorsomedial region of the medial superior temporal area (MSTd) have large receptive fields that include the fovea, are directionally selective for moving visual stimuli, prefer the motion of large fields to small spots, and respond to rotating and expanding patterns of motion as well as frontal parallel planar motion. These characteristics suggested that these neurons might contribute to the analysis of the large-field optic flow stimulation generated as an observer moves through the visual environment. 2. We tested the response of MSTd neurons in two awake monkeys by systematically presenting a set of translational and rotational stimuli to each neuron. These 100 X 100 degrees stimuli were the motion components from which all optic flow fields are derived. 3. In 220 single neurons we found 23% that responded primarily to one component of motion (planar, circular, or radial), 34% that responded to two components (planocircular or planoradial, but never circuloradial), and 29% that responded to all three components. 4. The number of stimulus components to which a neuron responded was unrelated to the size or eccentricity of its receptive field. 5. Triple-, double-, and single-component neurons varied widely in the strength of their responses to the preferred components. Grouping these neurons together revealed that they did not form discrete classes but rather a continuum of response selectivity. 6. This continuum was apparent in other response characteristics. Direction selectivity was weakest in triple-component neurons, strongest in single-component neurons. Significant inhibitory responses were less frequent in triple-component neurons than in single-component neurons. 7. There was some indication that the neurons of similar component classes occupied adjacent regions within MSTd, but all combinations of component and direction selectivity were occasionally found in immediate juxtaposition. 8. Experiments on a subset of neurons showed that the speed of motion, the dot density, and the number of different speed planes in the display had little influence on these responses. 9. We conclude that the selective responses of many MSTd neurons to the rotational and translational components of optic flow make these neurons reasonable candidates for contributing to the analysis of optic flow fields.

Response to Motion in Extrastriate Area MSTl: Disparity Sensitivity

1999 ◽  
Vol 82 (5) ◽  
pp. 2462-2475 ◽  
Author(s):  
Satoshi Eifuku ◽  
Robert H. Wurtz
Keyword(s):  
Receptive Field ◽  
Tuning Curve ◽  
Receptive Fields ◽  
Relative Difference ◽  
Moving Object ◽  
Absolute Difference ◽  
Stimulus Motion ◽  
Temporal Area ◽  
Moving Stimuli ◽  
Medial Superior Temporal

Many neurons in the lateral-ventral region of the medial superior temporal area (MSTl) have a clear center surround separation in their receptive fields. Either moving or stationary stimuli in the surround modulates the response to moving stimuli in the center, and this modulation could facilitate the perceptual segmentation of a moving object from its background. Another mechanism that could facilitate such segmentation would be sensitivity to binocular disparity in the center and surround regions of the receptive fields of these neurons. We therefore investigated the sensitivity of these MSTl neurons to disparity ranging from three degrees crossed disparity (near) to three degrees uncrossed disparity (far) applied to both the center and the surround regions. Many neurons showed clear disparity sensitivity to stimulus motion in the center of the receptive field. About [Formula: see text] of 104 neurons had a clear peak in their response, whereas another [Formula: see text] had broader tuning. Monocular stimulation abolished the tuning. The prevalence of cells broadly tuned to near and far disparity and the reversal of preferred directions at different disparities observed in MSTd were not found in MSTl. A stationary surround at zero disparity simply modulated up or down the response to moving stimuli at different disparities in the receptive field (RF) center but did not alter the disparity tuning curve. When the RF center motion was held at zero disparity and the disparity of the stationary surround was varied, some surround disparities produced greater modulation of MSTl neuron response than did others. Some neurons with different disparity preferences in center and surround responded best to the relative disparity differences between center and surround, whereas others were related to the absolute difference between center and surround. The combination of modulatory surrounds and the sensitivity to relative difference between center and surround disparity make these MSTl neurons particularly well suited for the segmentation of a moving object from the background.

Pursuit and optokinetic deficits following chemical lesions of cortical areas MT and MST

1988 ◽  
Vol 60 (3) ◽  
pp. 940-965 ◽  
Author(s):  
M. R. Dursteler ◽  
R. H. Wurtz
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Visual Motion ◽  
Ibotenic Acid ◽  
Motion Processing ◽  
Temporal Area ◽  
Target Speed ◽  
Pursuit Eye Movements ◽  
Medial Superior Temporal ◽  
Visual Motion Processing

1. Previous experiments have shown that punctate chemical lesions within the middle temporal area (MT) of the superior temporal sulcus (STS) produce deficits in the initiation and maintenance of pursuit eye movements (10, 34). The present experiments were designed to test the effect of such chemical lesions in an area within the STS to which MT projects, the medial superior temporal area (MST). 2. We injected ibotenic acid into localized regions of MST, and we observed two deficits in pursuit eye movements, a retinotopic deficit and a directional deficit. 3. The retinotopic deficit in pursuit initiation was characterized by the monkey's inability to match eye speed to target speed or to adjust the amplitude of the saccade made to acquire the target to compensate for target motion. This deficit was related to the initiation of pursuit to targets moving in any direction in the visual field contralateral to the side of the brain with the lesion. This deficit was similar to the deficit we found following damage to extrafoveal MT except that the affected area of the visual field frequently extended throughout the entire contralateral visual field tested. 4. The directional deficit in pursuit maintenance was characterized by a failure to match eye speed to target speed once the fovea had been brought near the moving target. This deficit occurred only when the target was moving toward the side of the lesion, regardless of whether the target began to move in the ipsilateral or contralateral visual field. There was no deficit in the amplitude of saccades made to acquire the target, or in the amplitude of the catch-up saccades made to compensate for the slowed pursuit. The directional deficit is similar to the one we described previously following chemical lesions of the foveal representation in the STS. 5. Retinotopic deficits resulted from any of our injections in MST. Directional deficits resulted from lesions limited to subregions within MST, particularly lesions that invaded the floor of the STS and the posterior bank of the STS just lateral to MT. Extensive damage to the densely myelinated area of the anterior bank or to the posterior parietal area on the dorsal lip of the anterior bank produced minimal directional deficits. 6. We conclude that damage to visual motion processing in MST underlies the retinotopic pursuit deficit just as it does in MT. MST appears to be a sequential step in visual motion processing that occurs before all of the visual motion information is transmitted to the brainstem areas related to pursuit.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals How multisensory neurons solve causal inference

2021 ◽  
Vol 118 (32) ◽  
pp. e2106235118
Author(s):  
Reuben Rideaux ◽  
Katherine R. Storrs ◽  
Guido Maiello ◽  
Andrew E. Welchman
Keyword(s):  
Motion Estimation ◽  
Causal Inference ◽  
Visual Motion ◽  
Temporal Area ◽  
Medial Superior Temporal ◽  
Electrophysiological Recordings ◽  
Visual Motion Cues ◽  
Integrated Or ◽  
Self Motion ◽  
The Brain

Sitting in a static railway carriage can produce illusory self-motion if the train on an adjoining track moves off. While our visual system registers motion, vestibular signals indicate that we are stationary. The brain is faced with a difficult challenge: is there a single cause of sensations (I am moving) or two causes (I am static, another train is moving)? If a single cause, integrating signals produces a more precise estimate of self-motion, but if not, one cue should be ignored. In many cases, this process of causal inference works without error, but how does the brain achieve it? Electrophysiological recordings show that the macaque medial superior temporal area contains many neurons that encode combinations of vestibular and visual motion cues. Some respond best to vestibular and visual motion in the same direction (“congruent” neurons), while others prefer opposing directions (“opposite” neurons). Congruent neurons could underlie cue integration, but the function of opposite neurons remains a puzzle. Here, we seek to explain this computational arrangement by training a neural network model to solve causal inference for motion estimation. Like biological systems, the model develops congruent and opposite units and recapitulates known behavioral and neurophysiological observations. We show that all units (both congruent and opposite) contribute to motion estimation. Importantly, however, it is the balance between their activity that distinguishes whether visual and vestibular cues should be integrated or separated. This explains the computational purpose of puzzling neural representations and shows how a relatively simple feedforward network can solve causal inference.

Location and Functional Definition of Human Visual Motion Organization Using Functional Magnetic Resonance Imaging

2011 ◽  
pp. 18-27
Author(s):  
Tianyi Yan ◽  
Jinglong Wu
Keyword(s):  
Visual Field ◽  
Visual Motion ◽  
Receptive Fields ◽  
Superior Temporal Sulcus ◽  
Object Motion ◽  
Posterior Limb ◽  
Medial Superior Temporal ◽  
Processing Abilities ◽  
Mst Neurons ◽  
Definition Of

In humans, functional imaging studies have found a homolog of the macaque motion complex, MT+, which is suggested to contain both the middle temporal (MT) and medial superior temporal (MST) areas in the ascending limb of the inferior temporal sulcus. In the macaque, the motion-sensitive MT and MST areas are adjacent in the superior temporal sulcus. Electrophysiology has identified several motion-selective regions in the superior temporal sulcus (STS) of the macaque. Two of the best-studied areas include the MT and MST areas. The MT area has strong projections to the adjacent MST area and is typically subdivided into the dorsal (MSTd) and lateral (MSTl) subregions. While MT encodes the basic elements of motion, MST has higher-order motion-processing abilities and has been implicated in the perception of both object motion and self motion. The macaque MST area has been shown to have considerably larger receptive fields than the MT area. The receptive fields of MT cells typically extend only a few degrees into the ipsilateral visual field, while MST neurons have receptive fields that extend well into the ipsilateral visual field. This study tentatively identifies these subregions as the human homologs of the macaque MT and MST areas, respectively (Fig. 1). Putative human MT and MST areas were typically located on the posterior/ventral and anterior/dorsal banks of a dorsal/posterior limb of the inferior temporal sulcus. These locations are similar to their relative positions in the macaque superior temporal sulcus.

Discharge Characteristics of Pursuit Neurons in MST During Vergence Eye Movements

2005 ◽  
Vol 93 (5) ◽  
pp. 2415-2434 ◽  
Author(s):  
Teppei Akao ◽  
Michael J. Mustari ◽  
Junko Fukushima ◽  
Sergei Kurkin ◽  
Kikuro Fukushima
Keyword(s):  
Eye Movements ◽  
Visual Motion ◽  
Significant Proportion ◽  
Visual Signals ◽  
Visual Responses ◽  
Discharge Characteristics ◽  
Temporal Area ◽  
Mst Neurons ◽  
Pursuit Neurons ◽  
Vergence Tracking

For small objects moving smoothly in space close to the observer, smooth pursuit and vergence eye movements maintain target images near the foveae to insure high-resolution processing of visual signals about moving objects. Signals for both systems must be synthesized for pursuit-in-three-dimensions (3D). Recent studies have shown that responses of the majority of pursuit neurons in the frontal eye fields (FEF) code pursuit-in-3D. This area is known to have reciprocal connections with the medial superior temporal area (MST) where frontal pursuit neurons are found. To examine whether pursuit-in-3D signals are already present in MST and how MST neurons discharge during vergence-tracking induced by a small spot, we examined discharge of MST pursuit neurons in 2 monkeys. Of a total of 219 pursuit neurons examined during both frontal pursuit and vergence-tracking, 61% discharged only for frontal pursuit, 18% only for vergence-tracking, and 21% for both. A majority of vergence-related MST neurons exhibited sensitivity to vergence eye velocity. Their discharge was maintained during brief blanking of a vergence target. About 1/3 of vergence-related MST neurons exhibited visual responses to spot motion in depth. The preferred directions for visual motion and vergence-tracking were similar in half of our population. Some of the remaining neurons showed opposite preferred directions. A significant proportion (29%) of vergence-related neurons discharged before onset of eye movements with lead times longer than 20 ms. The results in this and previous studies indicate differences in discharge characteristics of FEF and MST pursuit neurons, suggesting different roles for the two in pursuit-in-3D.

Optic Flow Signals in Extrastriate Area MST: Comparison of Perceptual and Neuronal Sensitivity

2004 ◽  
Vol 91 (3) ◽  
pp. 1314-1326 ◽  
Author(s):  
Hilary W. Heuer ◽  
Kenneth H. Britten
Keyword(s):  
Optic Flow ◽  
Visual Motion ◽  
Extrastriate Cortex ◽  
Sufficient Information ◽  
Temporal Area ◽  
Medial Superior Temporal ◽  
Wide Range ◽  
Behavioral Choices ◽  
Behavioral Sensitivity

The medial superior temporal area of extrastriate cortex (MST) contains signals selective for nonuniform patterns of motion often termed “optic flow.” The presence of such tuning, however, does not necessarily imply involvement in perception. To quantify the relationship between these selective neuronal signals and the perception of optic flow, we designed a discrimination task that allowed us to simultaneously record neuronal and behavioral sensitivities to near-threshold optic flow stimuli tailored to MST cells' preferences. In this two-alternative forced-choice task, we controlled the salience of globally opposite patterns (e.g., expansion and contraction) by varying the coherence of the motion. Using these stimuli, we could both relate the sensitivity of neuronal signals in MST to the animal's behavioral sensitivity and also measure trial-by-trial correlation between neuronal signals and behavioral choices. Neurons in MST showed a wide range of sensitivities to these complex motion stimuli. Many neurons had sensitivities equal or superior to the monkey's threshold. On the other hand, trial-by-trial correlation between neuronal discharge and choice (“choice probability”) was weak or nonexistent in our data. Together, these results lead us to conclude that MST contains sufficient information for threshold judgments of optic flow; however, the role of MST activity in optic flow discriminations may be less direct than in other visual motion tasks previously described by other laboratories.

Ventral intraparietal area of the macaque: anatomic location and visual response properties

1993 ◽  
Vol 69 (3) ◽  
pp. 902-914 ◽  
Author(s):  
C. L. Colby ◽  
J. R. Duhamel ◽  
M. E. Goldberg
Keyword(s):  
Visual Motion ◽  
Visual Response ◽  
Intraparietal Sulcus ◽  
Stimulus Motion ◽  
Area Mt ◽  
Temporal Area ◽  
Response Properties ◽  
Preferred Direction ◽  
The Face ◽  
Ventral Intraparietal Area

1. The middle temporal area (MT) projects to the intraparietal sulcus in the macaque monkey. We describe here a discrete area in the depths of the intraparietal sulcus containing neurons with response properties similar to those reported for area MT. We call this area the physiologically defined ventral intraparietal area, or VIP. In the present study we recorded from single neurons in VIP of alert monkeys and studied their visual and oculomotor response properties. 2. Area VIP has a high degree of selectivity for the direction of a moving stimulus. In our sample 72/88 (80%) neurons responded at least twice as well to a stimulus moving in the preferred direction compared with a stimulus moving in the null direction. The average response to stimuli moving in the preferred direction was 9.5 times as strong as the response to stimuli moving in the opposite direction, as compared with 10.9 times as strong for neurons in area MT. 3. Many neurons were also selective for speed of stimulus motion. Quantitative data from 25 neurons indicated that the distribution of preferred speeds ranged from 10 to 320 degrees/s. The degree of speed tuning was on average twice as broad as that reported for area MT. 4. Some neurons (22/41) were selective for the distance at which a stimulus was presented, preferring a stimulus of equivalent visual angle and luminance presented near (within 20 cm) or very near (within 5 cm) the face. These neurons maintained their preference for near stimuli when tested monocularly, suggesting that visual cues other than disparity can support this response. These neurons typically could not be driven by small spots presented on the tangent screen (at 57 cm). 5. Some VIP neurons responded best to a stimulus moving toward the animal. The absolute direction of visual motion was not as important for these cells as the trajectory of the stimulus: the best stimulus was one moving toward a particular point on the face from any direction. 6. VIP neurons were not active in relation to saccadic eye movements. Some neurons (10/17) were active during smooth pursuit of a small target. 7. The predominance of direction and speed selectivity in area VIP suggests that it, like other visual areas in the dorsal stream, may be involved in the analysis of visual motion.

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