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Your search keyword '"Gruzelier, John H"' showing total 12 results
Start Over Author "Gruzelier, John H" Publisher wiley
12 results on '"Gruzelier, John H"'

1. Beneficial Effects of Electrostimulation Contingencies on Sustained Attention and Electrocortical Activity

Author

Chen, Max Jean-Lon, Thompson, Trevor, Kropotov, Yury, and Gruzelier, John H

Abstract

Introduction: Chinese acupuncture therapy has been practiced for more than 3000 years. According to neuroimaging studies, electroacupuncture has been demonstrated to be effective via control of the frequency parameter of stimulation, based on the theory of frequency modulation of brain function. Aims: To investigate the following: (1) possible sustained effects of acustimulation in improving perceptual sensitivity in attention by comparing before, during, and 5 min following stimulation; (2) relations between commission errors and the motor inhibition event‐related potential (ERP) component measured with independent component analysis (ICA); (3) whether habituation would be demonstrated in the sham control group and would be militated by acustimulation in the experimental groups. Results: Twenty‐seven subjects were divided into three groups (n = 9). d‐Prime (d′) derived from signal detection theory was used as an index of perceptual sensitivity in the visual continuous performance attention test. Increased d′ was found during both alternating frequency (AE) and low frequency (LE) stimulation, but with no change in the sham control group (SE). However, only following AE was there a sustained poststimulation effect. Spatial filtration‐based independent components (ICs) in the AE group revealed significantly decreased amplitudes of the motor inhibition ICs both during and poststimulation. There was a significant habituation effect from task repetition in the sham group with decreased amplitudes of ICs as follows: the visual comparison component difference between go (correct response) and nogo cues (correct withheld response), the P400 action monitoring and the working memory component in the nogo condition, and the passive auditory component on control trials. Conclusion: The results showed associations between acustimulation and improved perceptual sensitivity with sustained improvements following AE, but not LE stimulation. Improvements in commission errors in the AE group were related to the motor inhibition IC. The activational effects of acustimulation apparently attenuated the across‐task habituation that characterized the control group. Open Access CC-BY-NC

Published
2011

12. Dynamic changes of ICA-derived EEG functional connectivity in the resting state.

Author

Chen JL, Ros T, and Gruzelier JH

Subjects
Adult, Female, Humans, Male, Numerical Analysis, Computer-Assisted, Spectrum Analysis, Young Adult, Brain physiology, Brain Mapping, Electroencephalography, Principal Component Analysis, Rest physiology
Abstract

An emerging issue in neuroscience is how to identify baseline state(s) and accompanying networks termed "resting state networks" (RSNs). Although independent component analysis (ICA) in fMRI studies has elucidated synchronous spatiotemporal patterns during cognitive tasks, less is known about the changes in EEG functional connectivity between eyes closed (EC) and eyes open (EO) states, two traditionally used baseline indices. Here we investigated healthy subjects (n = 27) in EC and EO employing a four-step analytic approach to the EEG: (1) group ICA to extract independent components (ICs), (2) standardized low-resolution tomography analysis (sLORETA) for cortical source localization of IC network nodes, followed by (3) graph theory for functional connectivity estimation of epochwise IC band-power, and (4) circumscribing IC similarity measures via hierarchical cluster analysis and multidimensional scaling (MDS). Our proof-of-concept results on alpha-band power demonstrate five statistically clustered groups with frontal, central, parietal, occipitotemporal, and occipital sources. Importantly, during EO compared with EC, graph analyses revealed two salient functional networks with frontoparietal connectivity: a more medial network with nodes in the mPFC/precuneus which overlaps with the "default-mode network" (DMN), and a more lateralized network comprising the middle frontal gyrus and inferior parietal lobule, coinciding with the "dorsal attention network" (DAN). Furthermore, a separate MDS analysis of ICs supported the emergence of a pattern of increased proximity (shared information) between frontal and parietal clusters specifically for the EO state. We propose that the disclosed component groups and their source-derived EEG functional connectivity maps may be a valuable method for elucidating direct neuronal (electrophysiological) RSNs in healthy people and those suffering from brain disorders., (Copyright © 2012 Wiley Periodicals, Inc.)

Published
2013
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