Invisible visual stimuli elicit increases in alpha-band power

2014 ◽  
Vol 112 (5) ◽  
pp. 1082-1090 ◽  
Author(s):  
Isabelle Bareither ◽  
Maximilien Chaumon ◽  
Fosco Bernasconi ◽  
Arno Villringer ◽  
Niko A. Busch
Keyword(s):  
Cortical Excitability ◽  
Neuronal Response ◽  
Detection Threshold ◽  
Visual Stimuli ◽  
Response Patterns ◽  
Alpha Band ◽  
Noise Pattern ◽  
Band Power ◽  
Wide Range ◽  
Eeg Alpha

The cerebral cortex responds to stimuli of a wide range of intensities. Previous studies have demonstrated that undetectably weak somatosensory stimuli cause a functional deactivation or inhibition in somatosensory cortex. In the present study, we tested whether invisible visual stimuli lead to similar responses, indicated by an increase in EEG alpha-band power—an index of cortical excitability. We presented subliminal and supraliminal visual stimuli after estimating each participant's detection threshold. Stimuli consisted of peripherally presented small circular patches that differed in their contrast to a background consisting of a random white noise pattern. We demonstrate that subliminal and supraliminal stimuli each elicit specific neuronal response patterns. Supraliminal stimuli evoked an early, strongly phase-locked lower-frequency response representing the evoked potential and induced a decrease in alpha-band power from 400 ms on. By contrast, subliminal visual stimuli induced an increase of non-phase-locked power around 300 ms that was maximal within the alpha-band. This response might be due to an inhibitory mechanism, which reduces spurious visual activation that is unlikely to result from external stimuli.

scholarly journals Propofol Requirement and EEG Alpha Band Power During General Anesthesia Provide Complementary Views on Preoperative Cognitive Decline

2020 ◽  
Vol 12 ◽  
Author(s):  
Cyril Touchard ◽  
Jérôme Cartailler ◽  
Charlotte Levé ◽  
José Serrano ◽  
David Sabbagh ◽  
...  
Keyword(s):  
Cognitive Decline ◽  
General Anesthesia ◽  
Logistic Models ◽  
Alpha Band ◽  
Target Concentration ◽  
Operative Morbidity ◽  
Band Power ◽  
Cognitive Evaluation ◽  
Eeg Alpha ◽  
Better Than

Background: Although cognitive decline (CD) is associated with increased post-operative morbidity and mortality, routinely screening patients remains difficult. The main objective of this prospective study is to use the EEG response to a Propofol-based general anesthesia (GA) to reveal CD.Methods: 42 patients with collected EEG and Propofol target concentration infusion (TCI) during GA had a preoperative cognitive assessment using MoCA. We evaluated the performance of three variables to detect CD (MoCA < 25 points): age, Propofol requirement to induce unconsciousness (TCI at SEF95: 8–13 Hz) and the frontal alpha band power (AP at SEF95: 8–13 Hz).Results: The 17 patients (40%) with CD were significantly older (p < 0.001), had lower TCI (p < 0.001), and AP (p < 0.001). We found using logistic models that TCI and AP were the best set of variables associated with CD (AUC: 0.89) and performed better than age (p < 0.05). Propofol TCI had a greater impact on CD probability compared to AP, although both were complementary in detecting CD.Conclusion: TCI and AP contribute additively to reveal patient with preoperative cognitive decline. Further research on post-operative cognitive trajectory are necessary to confirm the interest of intra operative variables in addition or as a substitute to cognitive evaluation.

Identification of Schizophrenia Using EEG Alpha Band Power During Hyperventilation and Post-hyperventilation

2016 ◽  
Vol 36 (6) ◽  
pp. 901-911 ◽  
Author(s):  
Thilakavathi Bose ◽  
Shenbaga Devi Sivakumar ◽  
Bhanu Kesavamurthy
Keyword(s):  
Alpha Band ◽  
Band Power ◽  
Eeg Alpha

scholarly journals Mouse V1 population correlates of visual detection rely on heterogeneity within neuronal response patterns

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Jorrit S Montijn ◽  
Pieter M Goltstein ◽  
Cyriel MA Pennartz
Keyword(s):  
Visual Detection ◽  
Neuronal Response ◽  
Visual Stimuli ◽  
Response Strength ◽  
Response Patterns ◽  
Activation Patterns ◽  
Neuronal Populations ◽  
Two Photon ◽  
Primary Sensory Cortex

Previous studies have demonstrated the importance of the primary sensory cortex for the detection, discrimination, and awareness of visual stimuli, but it is unknown how neuronal populations in this area process detected and undetected stimuli differently. Critical differences may reside in the mean strength of responses to visual stimuli, as reflected in bulk signals detectable in functional magnetic resonance imaging, electro-encephalogram, or magnetoencephalography studies, or may be more subtly composed of differentiated activity of individual sensory neurons. Quantifying single-cell Ca2+ responses to visual stimuli recorded with in vivo two-photon imaging, we found that visual detection correlates more strongly with population response heterogeneity rather than overall response strength. Moreover, neuronal populations showed consistencies in activation patterns across temporally spaced trials in association with hit responses, but not during nondetections. Contrary to models relying on temporally stable networks or bulk signaling, these results suggest that detection depends on transient differentiation in neuronal activity within cortical populations.

scholarly journals Prestimulus alpha-band power biases visual discrimination confidence, but not accuracy

2016 ◽  
Author(s):  
Jason Samaha ◽  
Luca Iemi ◽  
Bradley R. Postle
Keyword(s):  
Cortical Excitability ◽  
Orientation Discrimination ◽  
Alpha Power ◽  
Alpha Band ◽  
Decision Confidence ◽  
Band Power ◽  
Power Prior ◽  
Perceptual Confidence ◽  
Eeg Recordings ◽  
Visual Cortical

AbstractOscillations in the alpha-band (8-13 Hz) of human electroencephalographic (EEG) recordings are thought to reflect cortical excitability. As such, the magnitude of alpha power prior to the onset of a near threshold visual stimulus has been shown to predict stimulus detectability. Mechanistically, however, non-specific increases in visual-cortical excitability should result in amplified signal as well as amplified noise, leaving actual discriminability unchanged. Using a two-choice orientation discrimination task with equally probable stimuli, we found that discrimination accuracy was unaffected by fluctuations in prestimulus alpha-band power. Decision confidence, on the other hand, was strongly negatively correlated with prestimulus alpha power. This finding constitutes a clear dissociation between objective and subjective measures of visual perception as a function of prestimulus cortical excitability. This dissociation is predicted by models of perceptual confidence under which the balance of evidence in favor of each choice drives objective performance but only the magnitude of evidence in favor of the chosen stimulus drives subjective reports, suggesting that human perceptual confidence can be suboptimal.

scholarly journals Effects of load and emotional state on EEG alpha-band power and inter-site synchrony during a visual working memory task

2020 ◽  
Vol 20 (5) ◽  
pp. 1122-1132
Author(s):  
Jessica Sanches Braga Figueira ◽  
Isabel de Paula Antunes David ◽  
Isabela Lobo ◽  
Luiza Bonfim Pacheco ◽  
Mirtes Garcia Pereira ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Emotional State ◽  
Memory Task ◽  
Alpha Band ◽  
Band Power ◽  
Eeg Alpha

scholarly journals Statistical validation of physiological indicators for non-invasive and hybrid driver drowsiness detection system

2009 ◽  
Vol 5 (2) ◽  
Author(s):  
Eugene Zilberg ◽  
Zheng Ming Xu ◽  
David Burton ◽  
Murad Karrar ◽  
Saroj Lal
Keyword(s):  
Detection System ◽  
Seat Belt ◽  
Alpha Band ◽  
Statistical Validation ◽  
Physiological Indicators ◽  
Car Seat ◽  
Non Invasive ◽  
Driver Drowsiness ◽  
Band Power ◽  
Eeg Alpha

A hybrid system for detecting driver drowsiness was examined by using piezofilm movement sensors integrated into the car seat, seat belt and steering wheel. Statistical associations between increase in the driver drowsiness and the non-invasive and conventional physiological indicators were investigated. Statistically significant associations were established for the analysed physiological indicators – car seat movement magnitude and (electroencephalogram) EEG alpha band power percentage. All of the associastions were physiologically plausible with increase in probability of drowsiness associated with increases in the EEG alpha band power percentage and reduction in the seat movement magnitude. Adding a non-invasive measure such as seat movement magnitude to any combination of the EEG derived physiological predictors always resulted in improvement of associations. These findings can serve as a foundation for designing the vehicle-based fatigue countermeasure device as well as highlight potential difficulties and limitations of detection algorithm for such devices.

scholarly journals Cortical Excitability across the ALS Clinical Motor Phenotypes

2021 ◽  
Vol 11 (6) ◽  
pp. 715
Author(s):  
Thanuja Dharmadasa
Keyword(s):  
Motor Cortex ◽  
Cortical Excitability ◽  
Phenotypic Variability ◽  
Specific Treatment ◽  
Underlying Disease ◽  
Selective Vulnerability ◽  
Clinical Feature ◽  
Cortical Hyperexcitability ◽  
Wide Range

Amyotrophic lateral sclerosis (ALS) is characterized by its marked clinical heterogeneity. Although the coexistence of upper and lower motor neuron signs is a common clinical feature for most patients, there is a wide range of atypical motor presentations and clinical trajectories, implying a heterogeneity of underlying pathogenic mechanisms. Corticomotoneuronal dysfunction is increasingly postulated as the harbinger of clinical disease, and neurophysiological exploration of the motor cortex in vivo using transcranial magnetic stimulation (TMS) has suggested that motor cortical hyperexcitability may be a critical pathogenic factor linked to clinical features and survival. Region-specific selective vulnerability at the level of the motor cortex may drive the observed differences of clinical presentation across the ALS motor phenotypes, and thus, further understanding of phenotypic variability in relation to cortical dysfunction may serve as an important guide to underlying disease mechanisms. This review article analyses the cortical excitability profiles across the clinical motor phenotypes, as assessed using TMS, and explores this relationship to clinical patterns and survival. This understanding will remain essential to unravelling central disease pathophysiology and for the development of specific treatment targets across the ALS clinical motor phenotypes.

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