scholarly journals Diminished Parietal Cortex Activity Associated with Poor Motion Direction Discrimination Performance in Schizophrenia

2009 ◽  
Vol 20 (7) ◽  
pp. 1749-1755 ◽  
Author(s):  
J. Wang ◽  
R. Brown ◽  
K. R. Dobkins ◽  
J. E. McDowell ◽  
B. A. Clementz
Keyword(s):  
Parietal Cortex ◽  
Discrimination Performance ◽  
Motion Direction ◽  
Direction Discrimination

scholarly journals Perceived direction of deformation flow

2019 ◽  
Author(s):  
Takahiro Kawabe
Keyword(s):  
Discrimination Performance ◽  
Natural World ◽  
Natural Image ◽  
Global Motion ◽  
Motion Direction ◽  
Image Deformation ◽  
Direction Discrimination ◽  
Transparent Liquid ◽  
Shearing Deformation ◽  
Opposite Motion

AbstractIn everyday circumstances, human observers can easily discriminate the direction of transparent liquid flow. However, the mechanism of direction discrimination is not so straightforward. The present study focused on the flow of image deformation, which is closely related to the flow of transparent liquid in the natural world. To determine what image information is important in discriminating the direction of deformation flow, a natural image in a stimulus clip was deformed by using a deformation vector map that translated leftward or rightward. The task of the observers was to judge whether the transparent liquid in the clip flowed leftward or rightward. Manipulating the amplitude of deformation, we found that the discrimination performance improved with the amplitude. Interestingly, the observers’ performance was high overall only when shearing deformation was applied to the stimuli, while the observers reported an opposite-motion direction when only compressive deformation was applied. We computationally analyzed motion statistics of stimuli and found that the combination of mean and skewness of horizontal motion vectors reliably predicted the performance. The results indicate that human observers use global motion directions in order to determine the direction of deformation flow.

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 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.

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 Sequential sensory and decision processing in posterior parietal cortex

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Guilhem Ibos ◽  
David J Freedman
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Sensory Information ◽  
Matching Task ◽  
Visual Features ◽  
Motion Direction ◽  
Sensory Stimuli ◽  
Cortex Area ◽  
Visual Matching ◽  
Posterior Parietal

Decisions about the behavioral significance of sensory stimuli often require comparing sensory inference of what we are looking at to internal models of what we are looking for. Here, we test how neuronal selectivity for visual features is transformed into decision-related signals in posterior parietal cortex (area LIP). Monkeys performed a visual matching task that required them to detect target stimuli composed of conjunctions of color and motion-direction. Neuronal recordings from area LIP revealed two main findings. First, the sequential processing of visual features and the selection of target-stimuli suggest that LIP is involved in transforming sensory information into decision-related signals. Second, the patterns of color and motion selectivity and their impact on decision-related encoding suggest that LIP plays a role in detecting target stimuli by comparing bottom-up sensory inputs (what the monkeys were looking at) and top-down cognitive encoding inputs (what the monkeys were looking for).

scholarly journals A simple linear readout of MT supports motion direction-discrimination performance

2020 ◽  
Vol 123 (2) ◽  
pp. 682-694 ◽  
Author(s):  
Jacob L. Yates ◽  
Leor N. Katz ◽  
Aaron J. Levi ◽  
Jonathan W. Pillow ◽  
Alexander C. Huk
Keyword(s):  
Temporal Dynamics ◽  
Temporal Integration ◽  
Discrimination Performance ◽  
Neuron Activity ◽  
Motion Direction ◽  
Temporal Area ◽  
Middle Temporal ◽  
Motion Discrimination ◽  
Temporal Properties ◽  
Middle Temporal Area

Motion discrimination is a well-established model system for investigating how sensory signals are used to form perceptual decisions. Classic studies relating single-neuron activity in the middle temporal area (MT) to perceptual decisions have suggested that a simple linear readout could underlie motion discrimination behavior. A theoretically optimal readout, in contrast, would take into account the correlations between neurons and the sensitivity of individual neurons at each time point. However, it remains unknown how sophisticated the readout needs to be to support actual motion-discrimination behavior or to approach optimal performance. In this study, we evaluated the performance of various neurally plausible decoders, trained to discriminate motion direction from small ensembles of simultaneously recorded MT neurons. We found that decoding the stimulus without knowledge of the interneuronal correlations was sufficient to match an optimal (correlation aware) decoder. Additionally, a decoder could match the psychophysical performance of the animals with flat integration of up to half the stimulus and inherited temporal dynamics from the time-varying MT responses. These results demonstrate that simple, linear decoders operating on small ensembles of neurons can match both psychophysical performance and optimal sensitivity without taking correlations into account and that such simple read-out mechanisms can exhibit complex temporal properties inherited from the sensory dynamics themselves. NEW & NOTEWORTHY Motion perception depends on the ability to decode the activity of neurons in the middle temporal area. Theoretically optimal decoding requires knowledge of the sensitivity of neurons and interneuronal correlations. We report that a simple correlation-blind decoder performs as well as the optimal decoder for coarse motion discrimination. Additionally, the decoder could match the psychophysical performance with moderate temporal integration and dynamics inherited from sensory responses.

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