Changes in EEG power spectra during biofeedback of slow cortical potentials in epilepsy

Author(s): Busch, S., Strehl, U., Birbaumer, N.

Journal/Book: Appl Psychophysiol Biofeedbac. 1999; 24: 233 Spring St, New York, NY 10013, USA. Kluwer Academic/Plenum Publ. 213-233.

Abstract: 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.

Note: Article Kotchoubey B, Univ Tubingen, Inst Med Psychol & Behav Neurobiol, Gartenstr 29 1, D-72074 Tubingen, GERMANY

Keyword(s): EEG biofeedback; epilepsy; slow cortical potentials; spectral analysis; SELF-REGULATION; TASK; RHYTHMS; BRAIN; SYNCHRONIZATION; PERFORMANCE; ACTIVATION; MEMORY

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