scholarly journals Neural mechanisms of speed perception: transparent motion

2013 ◽  
Vol 110 (9) ◽  
pp. 2007-2018 ◽  
Author(s):  
Bart Krekelberg ◽  
Richard J. A. van Wezel
Keyword(s):  
Visual Motion ◽  
Human Subjects ◽  
Temporal Cortex ◽  
Motion Patterns ◽  
Tuning Curves ◽  
Mt Neurons ◽  
Transparent Motion ◽  
Single Pattern ◽  
Speed Perception ◽  
Unidirectional Motion

Visual motion on the macaque retina is processed by direction- and speed-selective neurons in extrastriate middle temporal cortex (MT). There is strong evidence for a link between the activity of these neurons and direction perception. However, there is conflicting evidence for a link between speed selectivity of MT neurons and speed perception. Here we study this relationship by using a strong perceptual illusion in speed perception: when two transparently superimposed dot patterns move in opposite directions, their apparent speed is much larger than the perceived speed of a single pattern moving at that physical speed. Moreover, the sensitivity for speed discrimination is reduced for such bidirectional patterns. We first confirmed these behavioral findings in human subjects and extended them to a monkey subject. Second, we determined speed tuning curves of MT neurons to bidirectional motion and compared these to speed tuning curves for unidirectional motion. Consistent with previous reports, the response to bidirectional motion was often reduced compared with unidirectional motion at the preferred speed. In addition, we found that tuning curves for bidirectional motion were shifted to lower preferred speeds. As a consequence, bidirectional motion of some speeds typically evoked larger responses than unidirectional motion. Third, we showed that these changes in neural responses could explain changes in speed perception with a simple labeled line decoder. These data provide new insight into the encoding of transparent motion patterns and provide support for the hypothesis that MT activity can be decoded for speed perception with a labeled line model.

Motion Mechanisms in Macaque MT

2005 ◽  
Vol 93 (5) ◽  
pp. 2908-2921 ◽  
Author(s):  
Bart Krekelberg ◽  
Thomas D. Albright
Keyword(s):  
Visual Motion ◽  
Dynamic Range ◽  
Gain Control ◽  
Competitive Interaction ◽  
Energy Model ◽  
Temporal Area ◽  
Motion Patterns ◽  
Mt Neurons ◽  
Motion Energy ◽  
Energy Components

The macaque middle temporal area (MT) is exquisitely sensitive to visual motion and there is a large amount of evidence that neural activity in MT is tightly correlated with the perception of motion. The mechanisms by which MT neurons achieve their directional selectivity, however, have received considerably less attention. We investigated the motion–energy model as a description of motion mechanisms in macaque MT. We first confirmed one of the predictions of the motion–energy model; macaques—just like humans—perceive a reversed direction of motion when a stimulus reverses contrast with every displacement (reverse-phi). This reversal of perceived direction had a clear correlate in the neural responses of MT cells, which were predictive of the monkey's behavioral decisions. Second, we investigated how multiple motion–energy components are combined. Psychophysical data have been used to argue that motion–energy components representing opposite directions are subtracted from each other. Our data show, however, that the interactions among motion–energy components are more complex. In particular, we found that the influence of a given component on the response to a stimulus consisting of multiple components depends on factors other than the response to that component alone. This suggests that there are subthreshold nonlinear interactions among multiple motion–energy components; these could take place within MT or in earlier stages of the motion network such as V1. We propose a model that captures the complexity of these component interactions by means of a competitive interaction among the components. This provides a better description of the MT responses than the subtractive motion opponency envisaged in the motion–energy model, even when the latter is combined with a gain-control mechanism. The competitive interaction extends the dynamic range of the cells and allows them to provide information on more subtle changes in motion patterns, including changes that are not purely directional.

scholarly journals Visual motion integration of bidirectional transparent motion in mouse opto-locomotor reflexes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
L. A. M. H. Kirkels ◽  
W. Zhang ◽  
Z. Rezvani ◽  
R. J. A. van Wezel ◽  
M. M. van Wanrooij
Keyword(s):  
Visual Motion ◽  
Whole Body ◽  
Neural Responses ◽  
Visual Motion Perception ◽  
Transparent Motion ◽  
Integration Mechanisms ◽  
Sensory Evidence ◽  
Random Dot Patterns ◽  
Winner Take All ◽  
Unidirectional Motion

AbstractVisual motion perception depends on readout of direction selective sensors. We investigated in mice whether the response to bidirectional transparent motion, activating oppositely tuned sensors, reflects integration (averaging) or winner-take-all (mutual inhibition) mechanisms. We measured whole body opto-locomotor reflexes (OLRs) to bidirectional oppositely moving random dot patterns (leftward and rightward) and compared the response to predictions based on responses to unidirectional motion (leftward or rightward). In addition, responses were compared to stimulation with stationary patterns. When comparing OLRs to bidirectional and unidirectional conditions, we found that the OLR to bidirectional motion best fits an averaging model. These results reflect integration mechanisms in neural responses to contradicting sensory evidence as has been documented for other sensory and motor domains.

scholarly journals Misperceptions of speed are accounted for by the responses of neurons in macaque cortical area MT

2011 ◽  
Vol 105 (3) ◽  
pp. 1199-1211 ◽  
Author(s):  
Pınar Boyraz ◽  
Stefan Treue
Keyword(s):  
Human Subjects ◽  
General Mechanism ◽  
Physiological Data ◽  
Neural Basis ◽  
Area Mt ◽  
Temporal Area ◽  
Tuning Curves ◽  
Mt Neurons ◽  
Random Dot Patterns ◽  
Perceived Speed

In humans, the perceived speed of random dot patterns (RDP) moving within small apertures is faster than that of RDPs moving within larger apertures at the same physical speed. To investigate the neural basis of this illusion, we recorded the responses of direction- and speed-selective neurons in the middle temporal area (MT) of macaque monkeys to stimuli varying in size and speed. Our results show that the preferred speed of MT neurons is slower for smaller stimuli. This effect was larger for neurons preferring faster speeds, matching our psychophysical observation in human subjects that the magnitude of the misperception is larger at higher stimulus speeds. Our physiological data indicate that, across a population of speed-tuned neurons in MT, decreasing the size of a stimulus would shift the activity profile to neurons tuned for higher speeds. Modeling a labeled-line readout of this shifted profile, we show an increased apparent speed, in line with the psychophysical observations. This link strengthens the evidence for a causal role of area MT in speed perception. The systematic shift in tuning curves of single neurons with stimulus size might reflect a general mechanism for feature-mismatch illusions in visual perception.

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 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

scholarly journals Precision of working memory for visual motion sequences and transparent motion surfaces

2011 ◽  
Vol 11 (14) ◽  
pp. 2-2 ◽  
Author(s):  
N. Zokaei ◽  
N. Gorgoraptis ◽  
B. Bahrami ◽  
P. M. Bays ◽  
M. Husain
Keyword(s):  
Working Memory ◽  
Visual Motion ◽  
Transparent Motion

Human Updating of Visual Motion Direction During Head Rotations

2008 ◽  
Vol 99 (5) ◽  
pp. 2558-2576
Author(s):  
Mario Ruiz-Ruiz ◽  
Julio C. Martinez-Trujillo
Keyword(s):  
Visual Motion ◽  
Human Subjects ◽  
Head Tilt ◽  
Head Rotation ◽  
Three Dimensions ◽  
Spatial Updating ◽  
Motion Direction ◽  
Direction Discrimination ◽  
Head Rotations ◽  
Stimulus Direction

Previous studies have demonstrated that human subjects update the location of visual targets for saccades after head and body movements and in the absence of visual feedback. This phenomenon is known as spatial updating. Here we investigated whether a similar mechanism exists for the perception of motion direction. We recorded eye positions in three dimensions and behavioral responses in seven subjects during a motion task in two different conditions: when the subject's head remained stationary and when subjects rotated their heads around an anteroposterior axis (head tilt). We demonstrated that after head-tilt subjects updated the direction of saccades made in the perceived stimulus direction (direction of motion updating), the amount of updating varied across subjects and stimulus directions, the amount of motion direction updating was highly correlated with the amount of spatial updating during a memory-guided saccade task, subjects updated the stimulus direction during a two-alternative forced-choice direction discrimination task in the absence of saccadic eye movements (perceptual updating), perceptual updating was more accurate than motion direction updating involving saccades, and subjects updated motion direction similarly during active and passive head rotation. These results demonstrate the existence of an updating mechanism for the perception of motion direction in the human brain that operates during active and passive head rotations and that resembles the one of spatial updating. Such a mechanism operates during different tasks involving different motor and perceptual skills (saccade and motion direction discrimination) with different degrees of accuracy.

Analysis of Neural Interactions Explains the Activation of Occipital Cortex by an Auditory Stimulus

1998 ◽  
Vol 80 (5) ◽  
pp. 2790-2796 ◽  
Author(s):  
A. R. McIntosh ◽  
R. E. Cabeza ◽  
N. J. Lobaugh
Keyword(s):  
Auditory Stimulus ◽  
Structural Equation ◽  
Large Scale ◽  
Human Subjects ◽  
Premotor Cortex ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
Equation Modeling ◽  
Occipital Area ◽  
Neural Interactions

McIntosh, A. R., R. E. Cabeza, and N. J. Lobaugh. Analysis of neural interactions explains the activation of occipital cortex by an auditory stimulus . J. Neurophysiol. 80: 2790–2796, 1998. Large-scale neural interactions were characterized in human subjects as they learned that an auditory stimulus signaled a visual event. Once learned, activation of left dorsal occipital cortex (increased regional cerebral blood flow) was observed when the auditory stimulus was presented alone. Partial least-squares analysis of the interregional correlations (functional connectivity) between the occipital area and the rest of the brain identified a pattern of covariation with four dominant brain areas that could have mediated this activation: prefrontal cortex (near Brodmann area 10, A10), premotor cortex (A6), superior temporal cortex (A41/42), and contralateral occipital cortex (A18). Interactions among these regions and the occipital area were quantified with structural equation modeling to identify the strongest sources of the effect on left occipital activity (effective connectivity). Learning-related changes in feedback effects from A10 and A41/42 appeared to account for this change in occipital activity. Influences from these areas on the occipital area were initially suppressive, or negative, becoming facilitory, or positive, as the association between the auditory and visual stimuli was acquired. Evaluating the total effects within the functional models showed positive influences throughout the network, suggesting enhanced interactions may have primed the system for the now-expected visual discrimination. By characterizing both changes in activity and the interactions underlying sensory associative learning, we demonstrated how parts of the nervous system operate as a cohesive network in learning about and responding to the environment.

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