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.

Responses in ventral intraparietal area of awake macaque monkey to optic flow patterns corresponding to rotation of planes in depth can be explained by translation and expansion effects

1997 ◽  
Vol 14 (4) ◽  
pp. 633-646 ◽  
Author(s):  
S.J. Schaafsma ◽  
J. Duysens ◽  
C.C.A.M. Gielen
Keyword(s):  
Optic Flow ◽  
Macaque Monkey ◽  
Induced Responses ◽  
Temporal Area ◽  
Medial Superior Temporal ◽  
Preferred Direction ◽  
Optimal Direction ◽  
Mst Neurons ◽  
Ventral Intraparietal Area ◽  
Parallel Axis

AbstractThere is evidence that neurons in medial superior temporal area (MST) respond to rotation in depth of textured planes. MST neurons project to the ventral intraparietal area (VIP) and the question arises whether VIP neurons are responsive to rotation in depth as well. In the present study on awake monkeys, we have simulated movement of a flat board, covered with dots, by a computer. The two-dimensional images corresponded to the projection of structured planes rotating around a fronto-parallel axis. In the literature this stimulus is called fanning. Fanning effectively induced responses in VIP neurons. Most often the responses were nearly as strong as for translation, expansion/contraction, or rotation, indicating that there was no special sensitivity for rotation in depth. For neurons, sensitive to expansion, the response to fanning could often be explained by the positioning of the expanding part of the fanning stimulus over the area which was most responsive to expansion. For neurons which were direction selective to translation, the optimal direction of fanning was usually the same as the preferred direction for translation. It is concluded that VIP neurons may be sensitive to movement of structured planes but they are not specialized for the detection of such movement.

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.

Planar Directional Contributions to Optic Flow Responses in MST Neurons

1997 ◽  
Vol 77 (2) ◽  
pp. 782-796 ◽  
Author(s):  
Charles J. Duffy ◽  
Robert H. Wurtz
Keyword(s):  
Visual Field ◽  
Optic Flow ◽  
Circular Motion ◽  
Planar Motion ◽  
Global Motion ◽  
Temporal Area ◽  
Preferred Direction ◽  
Motion Stimulus ◽  
Mst Neurons ◽  
Vector Combination

Duffy, Charles J. and Robert H. Wurtz. Planar directional contributions to optic flow responses in MST neurons. J. Neurophysiol. 77: 782–796, 1997. Many neurons in the dorsal region of the medial superior temporal area (MSTd) of monkey cerebral cortex respond to optic flow stimuli in which the center of motion is shifted off the center of the visual field. Each shifted-center-of-motion stimulus presents both different directions of planar motion throughout the visual field and a unique pattern of global motion across the visual field. We investigated the contribution of planar motion to the responses of these neurons in two experiments. In the first, we compared the responses of 243 neurons to planar motion and to shifted-center-of-motion stimuli created by vector summation of planar motion and radial or circular motion. We found that many neurons preferred the same directions of motion in the combined stimuli as in the planar stimuli, but other neurons did not. When we divided our sample into one group with stronger directionality to both planar and vector combination stimuli and one group with weaker directionality, we found that the neurons with the stronger directionality were those that showed the greatest similarity in the preferred direction of motion for both the planar and combined stimuli. In a second set of experiments, we overlapped planar motion and radial or circular motion to create transparent stimuli with the same motion components as the vector combination stimuli, but without the shifted centers of motion. We found that the neurons that responded most strongly to the planar motion when it was combined with radial or circular motion also responded best when the planar motion was overlapped by a transparent motion stimulus. We conclude that the responses of those neurons with stronger directional responses to both the motion of planar and vector combination stimuli are most readily understood as responding to the total planar motion in the stimulus, a planar motion mechanism. Other neurons that had weaker directional responses showed no such similarity in the preferred directions of planar motion in the vector combination and the transparent overlap stimuli and fit best with a mechanism dependent on the global motion pattern. We also found that neurons having significant responses to both radial and circular motion also responded to the spiral stimuli that result from a vector combination of radial and circular motion. The preferred planar-spiral vector combination stimulus was frequently the one containing that neurons' preferred direction of planar motion, which makes them similar to other MSTd neurons.

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.

scholarly journals Neurons in the ventral intraparietal area of awake macaque monkey closely resemble neurons in the dorsal part of the medial superior temporal area in their responses to optic flow patterns

1996 ◽  
Vol 76 (6) ◽  
pp. 4056-4068 ◽  
Author(s):  
S. J. Schaafsma ◽  
J. Duysens
Keyword(s):  
Optic Flow ◽  
Scale Invariance ◽  
Direction Selectivity ◽  
Temporal Area ◽  
First Order ◽  
Medial Superior Temporal ◽  
Field Response ◽  
Random Dot Patterns ◽  
Ventral Intraparietal Area ◽  
Flow Components

1. Neurons in the ventral intraparietal area (VIP) are known to respond to translating random dot patterns. Such responses can be explained on the basis of the input of the middle temporal area (MT) to this area. Anatomic evidence has shown that VIP receives input from the dorsal part of the medial superior temporal area (MSTd) also. Neurons in the latter area are though to be involved in egomotion because they are sensitive to first-order optic flow components such as divergence and rotation. Because of their MT and MSTd input, neurons in VIP may be expected to show sensitivity to such first-order optic flow as well. 2. The question of whether VIP neurons are selective to translation and/or first-order optic flow was investigated quantitatively in two awake monkeys by recording the responses of 52 visually responsive units and by fitting their tuning curves. The responses after presentation of random dot patterns exhibiting either expansion, contraction, clockwise rotation, or anticlockwise rotation were compared with the responses to translation stimuli tested in eight directions. 3. Most VIP neurons showed clear direction-selective responses, particularly to expansion but sometimes also to a combination of components (spiral stimuli). 4. A typical feature of VIP neurons is that their responses to these optic flow components remain when different parts of the receptive field are stimulated separately (“scale invariance”). For the most responsive subfield the response was on average 93% of the whole field response. For all subfields the mean response was on average 64% of the whole field response. 5. To test whether the scale invariance arose from convergence of translation-sensitive subfields with radial or circular direction preferences (“mosaic hypothesis”), the direction selectivity for translating stimuli was tested over these subfields. Basically the direction selectivity for translation was unchanged in the various subfields, thereby excluding the direction mosaic hypothesis. 6. It is concluded that the receptive field characteristics of VIP are very similar to those of MSTd neurons.

scholarly journals Discharge Properties of MST Neurons That Project to the Frontal Pursuit Area in Macaque Monkeys

2005 ◽  
Vol 94 (2) ◽  
pp. 1084-1090 ◽  
Author(s):  
Anne K. Churchland ◽  
Stephen G. Lisberger
Keyword(s):  
Optic Flow ◽  
Action Potentials ◽  
Rhesus Monkeys ◽  
Statistical Significance ◽  
Image Motion ◽  
Antidromic Activation ◽  
Medial Superior Temporal ◽  
Mst Neurons ◽  
Direction Tuning ◽  
And Control

We have used antidromic activation to determine the functional discharge properties of neurons that project to the frontal pursuit area (FPA) from the medial-superior temporal visual area (MST). In awake rhesus monkeys, MST neurons were considered to be activated antidromically if they emitted action potentials at fixed, short latencies after stimulation in the FPA and if the activation passed the collision test. Antidromically activated neurons ( n = 37) and a sample of the overall population of MST neurons ( n = 110) then were studied during pursuit eye movements across a dark background and during laminar motion of a large random-dot texture and optic flow expansion and contraction during fixation. Antidromically activated neurons showed direction tuning during pursuit (25/37), during laminar image motion (21/37), or both (16/37). Of 27 neurons tested with optic flow stimuli, 14 showed tuning for optic flow expansion ( n = 10) or contraction ( n = 4). There were no statistically significant differences in the response properties of the antidromically activated and control samples. Preferred directions for pursuit and laminar image motion did not show any statistically significant biases, and the preferred directions for eye versus image motion in each sample tended to be equally divided between aligned and opposed. There were small differences between the control and antidromically activated populations in preferred speeds for laminar motion and optic flow; these might have reached statistical significance with larger samples of antidromically activated neurons. We conclude that the population of MST neurons projecting to the FPA is highly diverse and quite similar to the general population of neurons in MST.

scholarly journals Weighting neurons by selectivity produces near-optimal population codes

2019 ◽  
Vol 121 (5) ◽  
pp. 1924-1937
Author(s):  
Elizabeth Zavitz ◽  
Nicholas S. C. Price
Keyword(s):  
A Priori ◽  
Maximum Level ◽  
Optimization Methods ◽  
Neuronal Population ◽  
Direction Selectivity ◽  
Motion Direction ◽  
Temporal Area ◽  
Linear Discriminant ◽  
Preferred Direction

Perception is produced by “reading out” the representation of a sensory stimulus contained in the activity of a population of neurons. To examine experimentally how populations code information, a common approach is to decode a linearly weighted sum of the neurons’ spike counts. This approach is popular because of the biological plausibility of weighted, nonlinear integration. For neurons recorded in vivo, weights are highly variable when derived through optimization methods, but it is unclear how the variability affects decoding performance in practice. To address this, we recorded from neurons in the middle temporal area (MT) of anesthetized marmosets ( Callithrix jacchus) viewing stimuli comprising a sheet of dots that moved coherently in 1 of 12 different directions. We found that high peak response and direction selectivity both predicted that a neuron would be weighted more highly in an optimized decoding model. Although learned weights differed markedly from weights chosen according to a priori rules based on a neuron’s tuning profile, decoding performance was only marginally better for the learned weights. In the models with a priori rules, selectivity is the best predictor of weighting, and defining weights according to a neuron’s preferred direction and selectivity improves decoding performance to very near the maximum level possible, as defined by the learned weights. NEW & NOTEWORTHY We examined which aspects of a neuron’s tuning account for its contribution to sensory coding. Strongly direction-selective neurons are weighted most highly by optimal decoders trained to discriminate motion direction. Models with predefined decoding weights demonstrate that this weighting scheme causally improved direction representation by a neuronal population. Optimizing decoders (using a generalized linear model or Fisher’s linear discriminant) led to only marginally better performance than decoders based purely on a neuron’s preferred direction and selectivity.

scholarly journals Comparison of the Spatial Limits on Direction Selectivity in Visual Areas MT and V1

2005 ◽  
Vol 93 (3) ◽  
pp. 1235-1245 ◽  
Author(s):  
Mark M. Churchland ◽  
Nicholas J. Priebe ◽  
Stephen G. Lisberger
Keyword(s):  
Apparent Motion ◽  
Great Majority ◽  
Spatial Separation ◽  
Direction Selectivity ◽  
Temporal Separation ◽  
Temporal Area ◽  
Mean Values ◽  
V1 Neurons ◽  
Preferred Direction ◽  
The Difference

We recorded responses to apparent motion from directionally selective neurons in primary visual cortex (V1) of anesthetized monkeys and middle temporal area (MT) of awake monkeys. Apparent motion consisted of multiple stationary stimulus flashes presented in sequence, characterized by their temporal separation (Δ t) and spatial separation (Δ x). Stimuli were 8° square patterns of 100% correlated random dots that moved at apparent speeds of 16 or 32°/s. For both V1 and MT, the difference between the response to the preferred and null directions declined with increasing flash separation. For each neuron, we estimated the maximum flash separation for which directionally selective responses were observed. For the range of speeds we used, Δ x provided a better description of the limitation on directional responses than did Δ t. When comparing MT and V1 neurons of similar preferred speed, there was no difference in the maximum Δ x between our samples from the two areas. In both V1 and MT, the great majority of neurons had maximal values of Δ x in the 0.25–1° range. Mean values were almost identical between the two areas. For most neurons, larger flash separations led to both weaker responses to the preferred direction and increased responses to the opposite direction. The former mechanism was slightly more dominant in MT and the latter slightly more dominant in V1. We conclude that V1 and MT neurons lose direction selectivity for similar values of Δ x, supporting the hypothesis that basic direction selectivity in MT is inherited from V1, at least over the range of stimulus speeds represented by both areas.

Neural responses to visual texture patterns in middle temporal area of the macaque monkey

1992 ◽  
Vol 68 (1) ◽  
pp. 164-181 ◽  
Author(s):  
J. F. Olavarria ◽  
E. A. DeYoe ◽  
J. J. Knierim ◽  
J. M. Fox ◽  
D. C. van Essen
Keyword(s):  
Macaque Monkey ◽  
Direction Selectivity ◽  
Neural Responses ◽  
Temporal Area ◽  
Middle Temporal ◽  
Tuning Curves ◽  
Preferred Direction ◽  
Orientation Contrast ◽  
Background Texture ◽  
Moving Texture

1. We studied how neurons in the middle temporal visual area (MT) of anesthetized macaque monkeys responded to textured and nontextured visual stimuli. Stimuli contained a central rectangular ,figure- that was either uniform in luminance or consisted of an array of oriented line segments. The figure moved at constant velocity in one of four orthogonal directions. The region surrounding the figure was either uniform in luminance or contained a texture array (whose elements were identical or orthogonal in orientation to those of the figure), and it either was stationary or moved along with the figure. 2. A textured figure moving across a stationary textured background (,texture bar- stimulus) often elicited vigorous neural responses, but, on average, the responses to texture bars were significantly smaller than to solid (uniform luminance) bars. 3. Many cells showed direction selectivity that was similar for both texture bars and solid bars. However, on average, the direction selectivity measured when texture bars were used was significantly smaller than that for solid bars, and many cells lost significant direction selectivity altogether. The reduction in direction selectivity for texture bars generally reflected a combination of decreased responsiveness in the preferred direction and increased responsiveness in the null (opposite to preferred) direction. 4. Responses to a texture bar in the absence of a texture background (,texture bar alone-) were very similar to the responses to solid bars both in the magnitude of response and in the degree of direction selectivity. Conversely, adding a static texture surround to a moving solid bar reduced direction selectivity on average without a reduction in response magnitude. These results indicate that the static surround is largely responsible for the differences in direction selectivity for texture bars versus solid bars. 5. In the majority of MT cells studied, responses to a moving texture bar were largely independent of whether the elements in the bar were of the same orientation as the background elements or of the orthogonal orientation. Thus, for the class of stimuli we used, orientation contrast does not markedly affect the responses of MT neurons to moving texture patterns. 6. The optimum figure length and the shapes of the length tuning curves determined with the use of solid bars and texture bars differed significantly in most of the cells examined. Thus neurons in MT are not simply selective for a particular figure shape independent of whatever cues are used to delineate the figure.

scholarly journals Direction and Contrast Tuning of Macaque MSTd Neurons During Saccades

2009 ◽  
Vol 101 (6) ◽  
pp. 3100-3107 ◽  
Author(s):  
Nathan A. Crowder ◽  
Nicholas S. C. Price ◽  
Michael J. Mustari ◽  
Michael R. Ibbotson
Keyword(s):  
Visual Stimulation ◽  
Large Cell ◽  
Saccadic Suppression ◽  
Image Motion ◽  
Active Motion ◽  
Temporal Area ◽  
Full Field ◽  
Medial Superior Temporal ◽  
Preferred Direction ◽  
Direction Tuning

Saccades are rapid eye movements that change the direction of gaze, although the full-field image motion associated with these movements is rarely perceived. The attenuation of visual perception during saccades is referred to as saccadic suppression. The mechanisms that produce saccadic suppression are not well understood. We recorded from neurons in the dorsal medial superior temporal area (MSTd) of alert macaque monkeys and compared the neural responses produced by the retinal slip associated with saccades (active motion) to responses evoked by identical motion presented during fixation (passive motion). We provide evidence for a neural correlate of saccadic suppression and expand on two contentious results from previous studies. First, we confirm the finding that some neurons in MSTd reverse their preferred direction during saccades. We quantify this effect by calculating changes in direction tuning index for a large cell population. Second, it has been noted that neural activity associated with saccades can arrive in the parietal cortex ≤30 ms earlier than activity produced by similar visual stimulation during fixation. This led to the question of whether the saccade-related responses were visual in origin or were motor signals arising from saccade-planning areas of the brain. By comparing the responses to saccades made over textured backgrounds of different contrasts, we provide strong evidence that saccade-related responses were visual in origin. Refinements of the possible models of saccadic suppression are discussed.

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