scholarly journals Sensory and choice responses in MT distinct from motion encoding

2021 ◽  
Author(s):  
Aaron J Levi ◽  
Yuan Zhao ◽  
Il Memming Park ◽  
Alexander C Huk
Keyword(s):  
Visual Motion ◽  
Time Varying ◽  
Motion Direction ◽  
Population Activity ◽  
Motor Responses ◽  
Direction Discrimination ◽  
Multiple Components ◽  
Strategic Manipulation ◽  
Motion Responses ◽  
Correlated Signals

Macaque area MT is well known for its visual motion selectivity and relevance to motion perception, but the possibility of it also reflecting non-sensory functions has largely been ignored. Manipulating subjects' temporal evidence weighting revealed multiple components of MT responses that were, surprisingly, not interpretable as behaviorally-relevant modulations of motion encoding, nor as consequences of readout of motion direction. MT's time-varying motion-driven responses were starkly changed by our strategic manipulation, but with timecourses opposite the subjects' temporal weighting strategies. Furthermore, large choice-correlated signals were represented in population activity distinctly from motion responses (even after the stimulus) with multiple phases that both lagged psychophysical readout and preceded motor responses. These results reveal multiple cognitive contributions to MT responses that are task-related but not functionally relevant to encoding or decoding of motion for psychophysical direction discrimination, calling into question its nature as a simple sensory area.

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.

scholarly journals Motion Direction Discrimination with Tactile Random-Dot Kinematograms

i-Perception ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 204166952110046
Author(s):  
Scinob Kuroki ◽  
Shin’ya Nishida
Keyword(s):  
Motion Detection ◽  
Visual Motion ◽  
Discrimination Performance ◽  
Sensory Function ◽  
Human Observer ◽  
Motion Sensing ◽  
Motion Direction ◽  
Low Level ◽  
Direction Discrimination ◽  
High Level

Motion detection is a fundamental sensory function for multiple modalities, including touch, but the mechanisms underlying tactile motion detection are not well understood. While previous findings supported the existence of high-level feature tracking, it remains unclear whether there also exist low-level motion sensing that directly detects a local spatio-temporal correlation in the skin-stimulation pattern. To elucidate this mechanism, we presented, on braille displays, tactile random-dot kinematograms, similar to those widely used in visual motion research, which enables us to independently manipulate feature trackability and various parameters of local motion. We found that a human observer is able to detect the direction of difficult-to-track tactile motions presented to the fingers and palms. In addition, the direction-discrimination performance was better when the stimuli were presented along the fingers than when presented across the fingers. These results indicate that low-level motion sensing, in addition to high-level tracking, contribute to tactile motion perception.

scholarly journals Anodal Transcranial Direct Current Stimulation (tDCS) of hMT+ Does Not Affect Motion Perception Learning

2018 ◽  
Author(s):  
Stephanie J. Larcombe ◽  
Christopher Kennard ◽  
Jacinta O’Shea ◽  
Holly Bridge
Keyword(s):  
Task Performance ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Visual Motion ◽  
Training Session ◽  
Macaque Monkey ◽  
Anodal Tdcs ◽  
Motion Direction ◽  
Direct Current Stimulation ◽  
Direction Discrimination

AbstractBackgroundHuman visual cortical area hMT+, like its homologue MT in the macaque monkey, has been shown to be particularly selective to visual motion. After damage to the primary visual cortex (V1), patients often exhibit preserved ability to detect moving stimuli, which is associated with neural activity in area hMT+. As an anatomical substrate underlying residual function in the absence of V1, promoting functional plasticity in hMT+ could potentially boost visual performance despite cortical damage.ObjectiveTo establish in healthy participants whether it is possible to use transcranial direct current stimulation (tDCS) over hMT+ to potentiate learning of visual motion direction discrimination.MethodsParticipants were trained daily for five days on a visual motion direction discrimination task. Task difficulty was increased as performance improved, by decreasing the proportion of coherently moving dots, such that participants were always performing at psychophysical threshold. tDCS, either anodal or sham, was applied daily during the 20-minute training session. Task performance was assessed at baseline and at the end of the training period.ResultsAll participants showed improved task performance both during and after training. Contrary to our hypothesis, anodal tDCS did not further improve performance compared to sham stimulation. Bayesian statistics indicated significant evidence in favour of the null hypothesis.ConclusionAnodal tDCS to hMT+ does not enhance visual motion direction discrimination learning in the young healthy visual system.

The effect of TMS on visual motion sensitivity: an increase in neural noise or a decrease in signal strength?

2011 ◽  
Vol 106 (1) ◽  
pp. 138-143 ◽  
Author(s):  
Manuela Ruzzoli ◽  
Arman Abrahamyan ◽  
Colin W. G. Clifford ◽  
Carlo A. Marzi ◽  
Carlo Miniussi ◽  
...  
Keyword(s):  
Visual Motion ◽  
Single Pulse ◽  
Visual Signal ◽  
Motion Direction ◽  
Motion Sensitivity ◽  
Neural Noise ◽  
Sensory Signal ◽  
Direction Discrimination ◽  
Motion Stimulus ◽  
Underlying Mechanisms

The underlying mechanisms of action of transcranial magnetic stimulation (TMS) are still a matter of debate. TMS may impair a subject's performance by increasing neural noise, suppressing the neural signal, or both. Here, we delivered a single pulse of TMS (spTMS) to V5/MT during a motion direction discrimination task while concurrently manipulating the level of noise in the motion stimulus. Our results indicate that spTMS essentially acts by suppressing the strength of the relevant visual signal. We suggest that TMS may induce a pattern of neural activity that complements the ongoing activation elicited by the sensory signal in a manner that partially impoverishes that signal.

scholarly journals Low-dimensional encoding of decisions in parietal cortex reflects long-term training history

2021 ◽  
Author(s):  
Kenneth W Latimer ◽  
David J Freedman
Keyword(s):  
Parietal Cortex ◽  
Visual Motion ◽  
Stimulus Similarity ◽  
Motion Direction ◽  
Population Activity ◽  
Training History ◽  
Neural Computations ◽  
Sample Test ◽  
Low Dimensional

Neurons in parietal cortex exhibit task-related activity during decision-making tasks. However, it remains unclear how long-term training to perform different tasks over months or even years shapes neural computations and representations. We examine lateral intraparietal area (LIP) responses during a visual motion delayed-match-to-category (DMC) task. We consider two pairs of monkeys with different training histories: one trained only on the DMC task, and another first trained to perform fine motion-direction discrimination. We introduce generalized multilinear models to quantify low-dimensional, task-relevant components in population activity. During the DMC task, we found stronger cosine-like motion-direction tuning in the pretrained monkeys than in the DMC-only monkeys, and that the pretrained monkeys' performance depended more heavily on sample-test stimulus similarity. These results suggest that sensory representations in LIP depend on the sequence of tasks that the animals have learned, underscoring the importance of training history in studies with complex behavioral tasks.

scholarly journals Electrophysiological aftereffects of high-frequency transcranial random noise stimulation (hf-tRNS): an EEG investigation

2021 ◽  
Author(s):  
Filippo Ghin ◽  
Louise O’Hare ◽  
Andrea Pavan
Keyword(s):  
High Frequency ◽  
Discrimination Task ◽  
Temporal Dynamics ◽  
Random Noise ◽  
Decomposition Analysis ◽  
Oscillatory Activity ◽  
Motion Direction ◽  
Time Frequency ◽  
Direction Discrimination ◽  
Transcranial Random Noise Stimulation

AbstractThere is evidence that high-frequency transcranial random noise stimulation (hf-tRNS) is effective in improving behavioural performance in several visual tasks. However, so far there has been limited research into the spatial and temporal characteristics of hf-tRNS-induced facilitatory effects. In the present study, electroencephalogram (EEG) was used to investigate the spatial and temporal dynamics of cortical activity modulated by offline hf-tRNS on performance on a motion direction discrimination task. We used EEG to measure the amplitude of motion-related VEPs over the parieto-occipital cortex, as well as oscillatory power spectral density (PSD) at rest. A time–frequency decomposition analysis was also performed to investigate the shift in event-related spectral perturbation (ERSP) in response to the motion stimuli between the pre- and post-stimulation period. The results showed that the accuracy of the motion direction discrimination task was not modulated by offline hf-tRNS. Although the motion task was able to elicit motion-dependent VEP components (P1, N2, and P2), none of them showed any significant change between pre- and post-stimulation. We also found a time-dependent increase of the PSD in alpha and beta bands regardless of the stimulation protocol. Finally, time–frequency analysis showed a modulation of ERSP power in the hf-tRNS condition for gamma activity when compared to pre-stimulation periods and Sham stimulation. Overall, these results show that offline hf-tRNS may induce moderate aftereffects in brain oscillatory activity.

scholarly journals Neural selectivity for visual motion in macaque area V3A

2020 ◽  
Author(s):  
Nardin Nakhla ◽  
Yavar Korkian ◽  
Matthew R. Krause ◽  
Christopher C. Pack
Keyword(s):  
Visual Cortex ◽  
Optic Flow ◽  
Functional Role ◽  
Visual Motion ◽  
Flow Patterns ◽  
Brain Regions ◽  
Direction Selectivity ◽  
Motion Processing ◽  
Imaging Studies ◽  
Motion Direction

AbstractThe processing of visual motion is carried out by dedicated pathways in the primate brain. These pathways originate with populations of direction-selective neurons in the primary visual cortex, which project to dorsal structures like the middle temporal (MT) and medial superior temporal (MST) areas. Anatomical and imaging studies have suggested that area V3A might also be specialized for motion processing, but there have been very few studies of single-neuron direction selectivity in this area. We have therefore performed electrophysiological recordings from V3A neurons in two macaque monkeys (one male and one female) and measured responses to a large battery of motion stimuli that includes translation motion, as well as more complex optic flow patterns. For comparison, we simultaneously recorded the responses of MT neurons to the same stimuli. Surprisingly, we find that overall levels of direction selectivity are similar in V3A and MT and moreover that the population of V3A neurons exhibits somewhat greater selectivity for optic flow patterns. These results suggest that V3A should be considered as part of the motion processing machinery of the visual cortex, in both human and non-human primates.Significance statementAlthough area V3A is frequently the target of anatomy and imaging studies, little is known about its functional role in processing visual stimuli. Its contribution to motion processing has been particularly unclear, with different studies yielding different conclusions. We report a detailed study of direction selectivity in V3A. Our results show that single V3A neurons are, on average, as capable of representing motion direction as are neurons in well-known structures like MT. Moreover, we identify a possible specialization for V3A neurons in representing complex optic flow, which has previously been thought to emerge in higher-order brain regions. Thus it appears that V3A is well-suited to a functional role in motion processing.

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