Responses of MST neurons to plaid stimuli

2013 ◽  
Vol 110 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Farhan A. Khawaja ◽  
Liu D. Liu ◽  
Christopher C. Pack
Keyword(s):  
Motion Processing ◽  
Two Stage ◽  
Mt Neurons ◽  
V1 Neurons ◽  
Motion Integration ◽  
Medial Superior Temporal ◽  
Retinal Input ◽  
Third Stage ◽  
Mst Neurons ◽  
Velocity Selectivity

The estimation of motion information from retinal input is a fundamental function of the primate dorsal visual pathway. Previous work has shown that this function involves multiple cortical areas, with each area integrating information from its predecessors. Compared with neurons in the primary visual cortex (V1), neurons in the middle temporal (MT) area more faithfully represent the velocity of plaid stimuli, and the observation of this pattern selectivity has led to two-stage models in which MT neurons integrate the outputs of component-selective V1 neurons. Motion integration in these models is generally complemented by motion opponency, which refines velocity selectivity. Area MT projects to a third stage of motion processing, the medial superior temporal (MST) area, but surprisingly little is known about MST responses to plaid stimuli. Here we show that increased pattern selectivity in MST is associated with greater prevalence of the mechanisms implemented by two-stage MT models: Compared with MT neurons, MST neurons integrate motion components to a greater degree and exhibit evidence of stronger motion opponency. Moreover, when tested with more challenging unikinetic plaid stimuli, an appreciable percentage of MST neurons are pattern selective, while such selectivity is rare in MT. Surprisingly, increased motion integration is found in MST even for transparent plaid stimuli, which are not typically integrated perceptually. Thus the relationship between MST and MT is qualitatively similar to that between MT and V1, as repeated application of basic motion mechanisms leads to novel selectivities at each stage along the pathway.

scholarly journals Responses of Neurons in the Medial Superior Temporal Visual Area to Apparent Motion Stimuli in Macaque Monkeys

2007 ◽  
Vol 97 (1) ◽  
pp. 272-282 ◽  
Author(s):  
Anne K. Churchland ◽  
Xin Huang ◽  
Stephen G. Lisberger
Keyword(s):  
Firing Rate ◽  
Apparent Motion ◽  
Target Speed ◽  
Speed Increase ◽  
Mt Neurons ◽  
Medial Superior Temporal ◽  
Smooth Motion ◽  
The Difference ◽  
Mst Neurons ◽  
Vector Averaging

Monkeys fixated a stationary spot during presentation of dot textures that moved in apparent motion defined by the spatial and temporal separations, Δx and Δt, between successive flashes of each dot. For each neuron, we assessed the speed tuning for smooth motion (Δt = 2 or 4 ms) at speeds ≤128°/s and the effect of varying the value of Δt at speeds of 16 and 32°/s. Many medial superior temporal (MST) neurons, like middle temporal (MT) neurons, were tuned for the speed of smooth motion and showed decreases in firing rate as the value of Δt increased at a constant speed. A subset of MST neurons, however, showed monotonically increasing firing rates as a function of smooth stimulus speed and responses to apparent motion that paralleled a previously discovered illusion where estimates of target speed increase with the value of Δt. Opponent firing rate, defined as the difference between responses for motion in the preferred and opposite directions, peaked at values of Δt that were consistent with the behavioral illusion. Comparison with a new sample of MT neurons recorded with the same stimuli failed to reveal comparable effects. Attempts to map the population responses in MT and MST onto the behavioral illusion of increased speed succeeded by averaging the opponent response across MST neurons, but only by applying vector averaging to determine the preferred speed of the most active MT neurons. We suggest that a vector-averaging computation transforms MT's place code for target speed into the rate code of some MST neurons.

MST Neurons Code for Visual Motion in Space Independent of Pursuit Eye Movements

2007 ◽  
Vol 97 (5) ◽  
pp. 3473-3483 ◽  
Author(s):  
Naoko Inaba ◽  
Shigeru Shinomoto ◽  
Shigeru Yamane ◽  
Aya Takemura ◽  
Kenji Kawano
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Visual Motion ◽  
Neural Mechanism ◽  
Mt Neurons ◽  
Pursuit Eye Movements ◽  
Medial Superior Temporal ◽  
Counter Rotation ◽  
Induced Motion ◽  
Mst Neurons

When a person tracks a small moving object, the visual images in the background of the visual scene move across his/her retina. It, however, is possible to estimate the actual motion of the images despite the eye-movement-induced motion. To understand the neural mechanism that reconstructs a stable visual world independent of eye movements, we explored areas MT (middle temporal) and MST (medial superior temporal) in the monkey cortex, both of which are known to be essential for visual motion analysis. We recorded the responses of neurons to a moving textured image that appeared briefly on the screen while the monkeys were performing smooth pursuit or stationary fixation tasks. Although neurons in both areas exhibited significant responses to the motion of the textured image with directional selectivity, the responses of MST neurons were mostly correlated with the motion of the image on the screen independent of pursuit eye movement, whereas the responses of MT neurons were mostly correlated with the motion of the image on the retina. Thus these MST neurons were more likely than MT neurons to distinguish between external and self-induced motion. The results are consistent with the idea that MST neurons code for visual motion in the external world while compensating for the counter-rotation of retinal images due to pursuit eye movements.

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 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 Micropools of reliable area MT neurons explain rapid motion detection

2018 ◽  
Vol 120 (5) ◽  
pp. 2396-2409 ◽  
Author(s):  
Bryan M. Krause ◽  
Geoffrey M. Ghose
Keyword(s):  
Motion Detection ◽  
Rapid Detection ◽  
Threshold Model ◽  
Coherent Motion ◽  
Motion Processing ◽  
Precise Integration ◽  
Physiological Basis ◽  
Temporal Precision ◽  
Mt Neurons ◽  
Rapid Motion

Many models of perceptually based decisions postulate that actions are initiated when accumulated sensory signals reach a threshold level of activity. These models have received considerable neurophysiological support from recordings of individual neurons while animals are engaged in motion discrimination tasks. These experiments have found that the activity of neurons in a particular visual area strongly associated with motion processing (MT), when pooled over hundreds of milliseconds, is sufficient to explain behavioral timing and performance. However, this level of pooling may be problematic for urgent perceptual decisions in which rapid detection dictates temporally precise integration. In this paper, we explore the physiological basis of one such task in which macaques detected brief (~70 ms) transients of coherent motion within ~240 ms. We find that a simple linear summation model based on realistic stimulus responses of as few as 40 correlated neurons can predict the reliability and timing of rapid motion detection. The model naturally reproduces a distinctive physiological relationship observed in rapid detection tasks in which the individual neurons with the most reliable stimulus responses are also the most predictive of impending behavioral choices. Remarkably, we observed this relationship across our simulated neuronal populations even when all neurons within the pool were weighted equally with respect to readout. These results demonstrate that small numbers of reliable sensory neurons can dominate perceptual judgments without any explicit reliability based weighting and are sufficient to explain the accuracy, latency, and temporal precision of rapid detection. NEW & NOTEWORTHY Computational and psychophysical models suggest that performance in many perceptual tasks may be based on the preferential sampling of reliable neurons. Recent studies of MT neurons during rapid motion detection, in which only those neurons with the most reliable sensory responses were strongly predictive of the animals’ decisions, seemingly support this notion. Here we show that a simple threshold model without explicit reliability biases can explain both the behavioral accuracy and precision of these detections and the distribution of sensory- and choice-related signals across neurons.

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.

scholarly journals Pattern Motion Processing by MT Neurons

2019 ◽  
Vol 13 ◽  
Author(s):  
Parvin Zarei Eskikand ◽  
Tatiana Kameneva ◽  
Anthony N. Burkitt ◽  
David B. Grayden ◽  
Michael R. Ibbotson
Keyword(s):  
Motion Processing ◽  
Mt Neurons ◽  
Pattern Motion

A model for motion coherence and transparency

1994 ◽  
Vol 11 (6) ◽  
pp. 1205-1220 ◽  
Author(s):  
Hugh R. Wilson ◽  
Jeounghoon Kim
Keyword(s):  
Competitive Inhibition ◽  
Weighting Function ◽  
Coherent Motion ◽  
Motion Processing ◽  
Preferred Direction ◽  
Wide Range ◽  
Motion Coherence ◽  
Mst Neurons ◽  
Vector Sum ◽  
A Minor

AbstractA recent model for two-dimensional motion processing in MT has demonstrated that perceived direction can be accurately predicted by combining Fourier and non-Fourier component motion signals using a vector sum computation. The vector sum direction is computed by a neural network that weights Fourier and non-Fourier components by the cosine of the component direction relative to that of each pattern unit, after which competitive inhibition extracts the signals of the most active units. It is shown here that a minor modification of the connectivity in this network suffices to predict transitions from motion coherence to transparency under a wide range of circumstances. It is only necessary that the cosine weighting function and competitive inhibition be limited to directions within ± 120 deg of each pattern unit's preferred direction. This network responds by signaling one pattern direction for coherent motion but two distinct directions for transparent motion. Based on this, neural networks with properties of MT and MST neurons can automatically signal motion coherence or transparency. In addition, the model accurately predicts motion repulsion under transparency conditions.

When S-cones contribute to chromatic global motion processing

2007 ◽  
Vol 24 (1) ◽  
pp. 1-8 ◽  
Author(s):  
ALEXA I. RUPPERTSBERG ◽  
SOPHIE M. WUERGER ◽  
MARCO BERTAMINI
Keyword(s):  
Motion Processing ◽  
Current Debate ◽  
Color Contrast ◽  
Global Motion ◽  
Motion Direction ◽  
Motion Integration ◽  
Conflicting Evidence ◽  
Simple Detection ◽  
The Individual ◽  
Contrast Thresholds

There is common consensus now that color-defined motion can be perceived by the human visual system. For global motion integration tasks based on isoluminant random dot kinematograms conflicting evidence exists, whether observers can (Ruppertsberg et al., 2003) or cannot (Bilodeau & Faubert, 1999) extract a common motion direction for stimuli modulated along the isoluminant red-green axis. Here we report conditions, in which S-cones contribute to chromatic global motion processing. When the display included extra-foveal regions, the individual elements were large (∼0.3°) and the displacement was large (∼1°), stimuli modulated along the yellowish-violet axis proved to be effective in a global motion task. The color contrast thresholds for detection for both color axes were well below the contrasts required for global motion integration, and therefore the discrimination-to-detection ratio was >1. We conclude that there is significant S-cone input to chromatic global motion processing and the extraction of global motion is not mediated by the same mechanism as simple detection. Whether the koniocellular or the magnocellular pathway is involved in transmitting S-cone signals is a topic of current debate (Chatterjee & Callaway, 2002).

scholarly journals A role for terminators in motion processing by macaque MT neurons?

2010 ◽  
Vol 2 (7) ◽  
pp. 415-415 ◽  
Author(s):  
N. Majaj ◽  
M. A. Smith ◽  
A. Kohn ◽  
W. Bair ◽  
J. A. Movshon
Keyword(s):  
Motion Processing ◽  
Mt Neurons
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