scholarly journals Imperceptible Somatosensory Single Pulse and Pulse Train Stimulation Oppositely Modulate Mu Rhythm Activity and Perceptual Performance

2020 ◽  
Vol 30 (12) ◽  
pp. 6284-6295
Author(s):  
Fivos Iliopoulos ◽  
Birol Taskin ◽  
Arno Villringer ◽  
Till Nierhaus
Keyword(s):  
Single Pulse ◽  
Mu Rhythm ◽  
Neural Basis ◽  
Pulse Trains ◽  
Perceptual Performance ◽  
The Common ◽  
Three Delays ◽  
Rhythm Activity ◽  
Neural Signaling ◽  
Train Stimulation

Abstract Subliminal stimulation alters conscious perception – a potential mechanism is the modulation of cortical background rhythms especially in the alpha range. Here, in the human somatosensory domain, we assessed effects of subthreshold (imperceptible) electrical finger nerve stimulation – either presented as single pulses or as brief (1 s) 7 Hz pulse trains—on mu-alpha rhythm and perceptual performance. In electroencephalography, subthreshold single pulses transiently (~150–350 ms poststimulus) increased mu activity (event-related synchronization), while, interestingly, subthreshold trains led to prolonged (>1 s) mu desynchronization. In psychophysics, detection of near-threshold target stimuli was consistently reduced when presented together with subthreshold trains (at three delays), whereas for targets paired with subthreshold single pulses detection remained unaffected (30 and 180 ms) or was even elevated (60 ms). Though both imperceptible, single pulses and pulse trains exerted opposite effects on neural signaling and perception. We suggest that the common neural basis is preferential activation of cortical inhibitory interneurons. While the inhibitory impact of a subthreshold single pulse (reflected by mu synchronization) is not psychophysically detectable—rather perception may be facilitated—repetition of the same subthreshold pulse shifts the excitation-inhibition balance toward an inhibitory cortical state (reflected by perceptual impediment) accompanied by mu desynchronization. These differential findings provide novel insights on the notion of alpha activity mediating functional inhibition.

scholarly journals Crossmodal Classification of Mu Rhythm Activity during Action Observation and Execution Suggests Specificity to Somatosensory Features of Actions

2017 ◽  
Vol 37 (24) ◽  
pp. 5936-5947 ◽  
Author(s):  
Michel-Pierre Coll ◽  
Clare Press ◽  
Hannah Hobson ◽  
Caroline Catmur ◽  
Geoffrey Bird
Keyword(s):  
Action Observation ◽  
Mu Rhythm ◽  
Rhythm Activity

scholarly journals The Thousand-Pulsar-Array programme on MeerKAT – I. Science objectives and first results

2020 ◽  
Vol 493 (3) ◽  
pp. 3608-3615 ◽  
Author(s):  
Simon Johnston ◽  
A Karastergiou ◽  
M J Keith ◽  
X Song ◽  
P Weltevrede ◽  
...  
Keyword(s):  
Radio Emission ◽  
Single Pulse ◽  
Wide Band ◽  
Radio Pulsars ◽  
Pulse Trains ◽  
First Results ◽  
Dispersion Measures ◽  
Large Survey ◽  
First Time

ABSTRACT We report here on initial results from the Thousand-Pulsar-Array (TPA) programme, part of the Large Survey Project ‘MeerTime’ on the MeerKAT telescope. The interferometer is used in the tied-array mode in the band from 856 to 1712 MHz, and the wide band coupled with the large collecting area and low receiver temperature make it an excellent telescope for the study of radio pulsars. The TPA is a 5 year project, which aims at to observing (a) more than 1000 pulsars to obtain high-fidelity pulse profiles, (b) some 500 of these pulsars over multiple epochs, and (c) long sequences of single-pulse trains from several hundred pulsars. The scientific outcomes from the programme will include the determination of pulsar geometries, the location of the radio emission within the pulsar magnetosphere, the connection between the magnetosphere and the crust and core of the star, tighter constraints on the nature of the radio emission itself, as well as interstellar medium studies. First, results presented here include updated dispersion measures, 26 pulsars with Faraday rotation measures derived for the first time, and a description of interesting emission phenomena observed thus far.

scholarly journals Seeking the “beauty center” in the brain: A meta-analysis of fMRI studies of beautiful human faces and visual art

2016 ◽  
Author(s):  
Chuan-Peng Hu ◽  
Yi Huang ◽  
Simon B. Eickhoff ◽  
Kaiping Peng ◽  
Jie Sui
Keyword(s):  
Visual Art ◽  
Ventral Striatum ◽  
Meta Analysis ◽  
Likelihood Estimation ◽  
Brain Regions ◽  
Neural Basis ◽  
The Common ◽  
Conjunction Analysis ◽  
Human Faces ◽  
The Brain

AbstractThe existence of a common beauty is a long-standing debate in philosophy and related disciplines. In the last two decades, cognitive neuroscientists have sought to elucidate this issue by exploring the common neural basis of the experience of beauty. Still, empirical evidence for such common neural basis of different forms of beauty is not conclusive. To address this question, we performed an activation likelihood estimation (ALE) meta-analysis on the existing neuroimaging studies of beauty appreciation of faces and visual art by non-expert adults (49 studies, 982 participants, meta-data are available at https://osf.io/s9xds/). We observed that perceiving these two forms of beauty activated distinct brain regions: while the beauty of faces convergently activated the left ventral striatum, the beauty of visual art convergently activated the anterior medial prefrontal cortex (aMPFC). However, a conjunction analysis failed to reveal any common brain regions for the beauty of visual art and faces. The implications of these results are discussed.

The neural basis for violations of Weber’s law in self-motion perception

2021 ◽  
Vol 118 (36) ◽  
pp. e2025061118
Author(s):  
Jerome Carriot ◽  
Kathleen E. Cullen ◽  
Maurice J. Chacron
Keyword(s):  
Discrimination Performance ◽  
Fundamental Principle ◽  
Weber’S Law ◽  
Neural Basis ◽  
Sensory Stimuli ◽  
Weber's Law ◽  
Perceptual Performance ◽  
Improved Performance ◽  
Self Motion ◽  
Neural Variability

A prevailing view is that Weber’s law constitutes a fundamental principle of perception. This widely accepted psychophysical law states that the minimal change in a given stimulus that can be perceived increases proportionally with amplitude and has been observed across systems and species in hundreds of studies. Importantly, however, Weber’s law is actually an oversimplification. Notably, there exist violations of Weber’s law that have been consistently observed across sensory modalities. Specifically, perceptual performance is better than that predicted from Weber’s law for the higher stimulus amplitudes commonly found in natural sensory stimuli. To date, the neural mechanisms mediating such violations of Weber’s law in the form of improved perceptual performance remain unknown. Here, we recorded from vestibular thalamocortical neurons in rhesus monkeys during self-motion stimulation. Strikingly, we found that neural discrimination thresholds initially increased but saturated for higher stimulus amplitudes, thereby causing the improved neural discrimination performance required to explain perception. Theory predicts that stimulus-dependent neural variability and/or response nonlinearities will determine discrimination threshold values. Using computational methods, we thus investigated the mechanisms mediating this improved performance. We found that the structure of neural variability, which initially increased but saturated for higher amplitudes, caused improved discrimination performance rather than response nonlinearities. Taken together, our results reveal the neural basis for violations of Weber’s law and further provide insight as to how variability contributes to the adaptive encoding of natural stimuli with continually varying statistics.

scholarly journals Mechanisms and Dynamics of Cortical Motor Inhibition in the Stop-signal Paradigm: A TMS Study

2010 ◽  
Vol 22 (2) ◽  
pp. 225-239 ◽  
Author(s):  
Wery P. M. van den Wildenberg ◽  
Borís Burle ◽  
Franck Vidal ◽  
Maurits W. van der Molen ◽  
K. Richard Ridderinkhof ◽  
...  
Keyword(s):  
Time Course ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Single Pulse ◽  
Stop Signal ◽  
Neural Basis ◽  
Manual Response ◽  
Inhibitory Circuits ◽  
Voluntary Behavior

The ability to stop ongoing motor responses in a split-second is a vital element of human cognitive control and flexibility that relies in large part on prefrontal cortex. We used the stop-signal paradigm to elucidate the engagement of primary motor cortex (M1) in inhibiting an ongoing voluntary motor response. The stop-signal paradigm taps the ability to flexibly countermand ongoing voluntary behavior upon presentation of a stop signal. We applied single-pulse TMS to M1 at several intervals following the stop signal to track the time course of excitability of the motor system related to generating and stopping a manual response. Electromyography recorded from the flexor pollicis brevis allowed quantification of the excitability of the corticospinal tract and the involvement of intracortical GABABergic circuits within M1, indexed respectively by the amplitude of the motor-evoked potential and the duration of the late part of the cortical silent period (SP). The results extend our knowledge of the neural basis of inhibitory control in three ways. First, the results revealed a dynamic interplay between response activation and stopping processes at M1 level during stop-signal inhibition of an ongoing response. Second, increased excitability of inhibitory interneurons that drives SP prolongation was evident as early as 134 msec following the instruction to stop. Third, this pattern was followed by a stop-related reduction of corticospinal excitability implemented around 180 after the stop signal. These findings point to the recruitment of GABABergic intracortical inhibitory circuits within M1 in stop-signal inhibition and support the notion of stopping as an active act of control.

Effect of number of stimuli and timing of twitch application on variability in interpolated twitch torque

2001 ◽  
Vol 90 (3) ◽  
pp. 1036-1040 ◽  
Author(s):  
Esther Suter ◽  
Walter Herzog
Keyword(s):  
Motor Unit ◽  
Muscle Activation ◽  
Single Pulse ◽  
Time Intervals ◽  
Large Variability ◽  
Stochastic Nature ◽  
Single Twitch ◽  
Train Stimulation ◽  
Time Point

Application of a supramaximal electrical twitch to the voluntarily contracted muscle is used to assess the level of muscle activation. Large variability in the interpolated twitch torque (ITT) has been observed when repeated stimulations are performed. It is hypothesized that this variability in ITT is caused by the stochastic nature of the timing of twitch application relative to pulses of voluntary excitation trains. Two experiments were performed on 12 subjects each to test this hypothesis. For the first experiment, a single twitch was superimposed on a train stimulation at different time intervals relative to the train pulses. For the second experiment, single, double, triple, or quadruple twitches were applied on a voluntarily contracted muscle. The ITT critically depended on the time point of twitch application: a single pulse applied 5 ms before a train pulse consistently evoked higher ITTs than all other stimulation conditions. Furthermore, variability of the ITT decreased as the number of applied twitches increased. The results support the hypothesis that a large part of the variability in the ITT may be caused by the timing of the superimposed twitch relative to the motor unit trains. The variability may be reduced by increasing the number of superimposed twitches.

scholarly journals Cortico-Cortical Interactions in Spatial Attention: A Combined ERP/TMS Study

2006 ◽  
Vol 95 (5) ◽  
pp. 3277-3280 ◽  
Author(s):  
Giorgio Fuggetta ◽  
Enea F. Pavone ◽  
Vincent Walsh ◽  
Monika Kiss ◽  
Martin Eimer
Keyword(s):  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Response Times ◽  
Event Related Potentials ◽  
Single Pulse ◽  
Behavioral Effect ◽  
Search Display ◽  
Delayed Response ◽  
Neural Basis ◽  
Related Potentials

To gain insight into the neural basis of visual attention, we combined transcranial magnetic stimulation (TMS) and event-related potentials (ERPs) during a visual search task. Single-pulse TMS over right posterior parietal cortex (rPPC) delayed response times to targets during conjunction search, and this behavioral effect had a direct ERP correlate. The early phase of the N2pc component that reflects the focusing of attention onto target locations in a search display was eliminated over the right hemisphere when TMS was applied there but was present when TMS was delivered to a control site (vertex). This finding demonstrates that rPPC TMS interferes with attentional selectivity in remote visual areas.

Periodic surface structures induced by femtosecond laser single pulse and pulse trains on metals

Laser Physics ◽  
2015 ◽  
Vol 25 (5) ◽  
pp. 056103 ◽  
Author(s):  
Jun Xie ◽  
Feng Wang ◽  
Lan Jiang ◽  
Liangliang Zhao ◽  
Yongfeng Lu
Keyword(s):  
Femtosecond Laser ◽  
Single Pulse ◽  
Surface Structures ◽  
Periodic Surface ◽  
Pulse Trains

scholarly journals A neural basis for the spatial suppression of visual motion perception

2016 ◽  
Author(s):  
Liu D. Liu ◽  
Ralf M. Haefner ◽  
Christopher C. Pack
Keyword(s):  
Cortical Area ◽  
Visual Motion ◽  
Receptive Fields ◽  
Stimulus Size ◽  
Neural Mechanisms ◽  
Stimulus Information ◽  
Neural Basis ◽  
Visual Motion Perception ◽  
Neuronal Populations ◽  
Perceptual Performance

AbstractIn theory, sensory perception should be more accurate when more neurons contribute to the representation of a stimulus. However, psychophysical experiments that use larger stimuli to activate larger pools of neurons sometimes report impoverished perceptual performance. To determine the neural mechanisms underlying these paradoxical findings, we trained monkeys to discriminate the direction of motion of visual stimuli that varied in size across trials, while simultaneously recording from populations of motion-sensitive neurons in cortical area MT. We used the resulting data to constrain a computational model that explained the behavioral data as an interaction of three main mechanisms: noise correlations, which prevented stimulus information from growing with stimulus size; neural surround suppression, which decreased sensitivity for large stimuli; and a read-out strategy that emphasized neurons with receptive fields near the stimulus center. These results suggest that paradoxical percepts reflect tradeoffs between sensitivity and noise in neuronal populations.

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