Changes in EEG Power Spectra During Biofeedback of Slow Cortical Potentials in Epilepsy

Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Germany.
Applied Psychophysiology and Biofeedback (Impact Factor: 1.13). 01/2000; 24(4):213-33. DOI: 10.1023/A:1022226412991
Source: PubMed


The goal of the study was to explore parallel changes in EEG spectral frequencies during biofeedback of slow cortical potentials (SCPs) in epilepsy patients. Thirty-four patients with intractable focal epilepsy participated in 35 sessions of SCP self-regulation training. The spectral analysis was carried out for the EEG recorded at the same electrode site (Cz) that was used for SCP feedback. The most prominent effect was the increase in the theta 2 power (6.0-7.9 Hz) and the relative power decrement in all other frequency bands (particularly delta 1, alpha 2 and beta 2) in transfer trials (i.e., where patients controlled their SCPs without continuous feedback) compared with feedback trials. In the second half of the training course (i.e., sessions 21-35) larger power values in the delta, theta, and alpha bands were found when patients were required to produce positive versus negative SCP shifts. Both across-subject and across-session (within-subject) correlations between spectral EEG parameters, on the one hand, and SCP data, on the other hand, were low and inconsistent, contrary to high and stable correlations between different spectral variables. This fact, as well as the lack of considerable task-dependent effects during the first part of training, indicates that learned SCP shifts did not directly lead to the specific dynamics of the EEG power spectra. Rather, these dynamics were related to nonspecific changes in patients' brain state.

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    • "oss studies suggest that about a third of the participants ultimately can be classified as so - called non - responders : subjects who do not learn to significantly modulate their brain activity over the course of the training in accor - dance with instructions ( e . g . , Doehnert et al . , 2008 ; Drechsler et al . , 2007 ; Fuchs et al . , 2003 ; Kotchoubey et al . , 1999 ) . Correspondingly , non - responding participants also tend not to show changes in behav - ioral outcome measures ( e . g . , Hanslmayr et al . , 2005 ; Lubar et al . , 1995 ) . Yet , one also has to acknowledge that there is no real consensus on how to actually define success in a neurofeedback training study ."
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    Full-text · Article · Sep 2013 · International journal of psychophysiology: official journal of the International Organization of Psychophysiology
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    • "Taking into account frequencies from 0.3 to 30 Hz, they found larger power values in the delta, theta and alpha bands when patient were required to produce positive vs. negative SCP shifts. However the effects were too weak and unstable to be regarded as an immediate consequence of SCP dynamics (Kotchoubey et al., 1999). Despite considerable research on the mechanisms and effectiveness of EEG feedback, the interaction of neocortical DC potentials recorded with scalp EEG and activity in the epileptogenic area in deeper structures is still unclear. "
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    • "The learned regulation of cortical activity was even applied to control computer devices [McFarland and Wolpaw, 2003]. Although its clinical utility is still an active area of investigation, EEG-based self-training and the learning of neurophysiological processes/behavior have already been applied to the management of attention deficiency and hyperactivity disorder (ADHD) [Lubar et al., 1995; Fernandez et al., 2003] and to the treatment of phobic anxiety as well as seizure-related disorders [Walley et al., 1994; Swingle, 1998; Kotchoubey et al., 1999]. These EEG-mediated approaches, however, lack the spatial specificity required to characterize regional brain activity since detected EEG signals reflect the activation of a widespread network of cortical/subcortical function. "
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