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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    ABSTRACT: Neurofeedback training procedures designed to alter a person's brain activity have been in use for nearly four decades now and represent one of the earliest applications of brain computer interfaces (BCI). The majority of studies using neurofeedback technology relies on recordings of the electroencephalogram (EEG) and applies neurofeedback in clinical contexts, exploring its potential as treatment for psychopathological syndromes. This clinical focus significantly affects the technology behind neurofeedback BCIs. For example, in contrast to other BCI applications, neurofeedback BCIs usually rely on EEG-derived features with only a minimum of additional processing steps being employed. Here, we highlight the peculiarities of EEG-based neurofeedback BCIs and consider their relevance for software implementations. Having reviewed already existing packages for the implementation of BCIs, we introduce our own solution which specifically considers the relevance of multi-subject handling for experimental and clinical trials, for example by implementing ready-to-use solutions for pseudo-/sham-neurofeedback.
    International journal of psychophysiology: official journal of the International Organization of Psychophysiology 09/2013; 91(1). DOI:10.1016/j.ijpsycho.2013.08.011 · 2.88 Impact Factor
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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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    ABSTRACT: Despite considerable research on EEG-feedback of slow cortical potentials (SCPs) for seizure control in epilepsy, the underlying mechanisms and the direct effects on intracerebral pathological activity within the focal area remain unclear. Intrahippocampal EEG recordings from four patients with temporal lobe epilepsy and implanted electrodes were analyzed with regard to spike activity and power in 10 frequency bands (0.5-148Hz) during SCP feedback based on surface recordings (position Cz). Trials with positive, negative and indifferent SCPs were contrasted. Three of the four patients showed changes in spike activity during SCPs, but these were inconsistent between patients, and resulted in increased and decreased activity in both positive and negative SCPs. Spectral analysis revealed that in all patients, positive surface shifts showed a bi-hemispheric higher power in the high-frequency activity above 40Hz. Two patients showed a higher power also during negative shifts, both in high-frequency activity and one in most other frequency bands. Feedback-related power effects did not differ between focal and non-focal side. The inconsistent change in spiking activity and the lack of decrease of power in pathology associated frequency bands during SCPs show that these SCPs do not decrease pathological activity within the epileptic focus. A possible relation of higher power in high-frequency activity during positive SCPs to cognitive processes, such as memory functions, is discussed.
    Epilepsy research 06/2011; 95(1-2):136-43. DOI:10.1016/j.eplepsyres.2011.03.012 · 2.02 Impact Factor
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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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    ABSTRACT: We report the long-term effect of real-time functional MRI (rtfMRI) training on voluntary regulation of the level of activation from a hand motor area. During the performance of a motor imagery task of a right hand, blood-oxygenation-level-dependent (BOLD) signal originating from a primary motor area was presented back to the subject in real-time. Demographically matched individuals also received the same procedure without valid feedback information. Followed by the initial rtfMRI sessions, both groups underwent two-week long, daily-practice of the task. Off-line data analysis revealed that the individuals in the experimental group were able to increase the level of BOLD signal from the regulatory target to a greater degree compared to the control group. Furthermore, the learned level of activation was maintained after the two-week period, with the recruitment of additional neural circuitries such as the hippocampus and the limbo-thalamo-cortical pathway. The activation obtained from the control group, in the absence of proper feedback, was indifferent across the training conditions. The level of BOLD activity from the target regulatory region was positively correlated with a self evaluative score within the experimental group, while the majority of control subjects had difficulty adopting a strategy to attain the desired level of functional regulation. Our results suggest that rtfMRI helped individuals learn how to increase region-specific cortical activity associated with a motor imagery task, and the level of increased activation in motor areas was consolidated after the two-week self-practice period, with the involvement of neural circuitries implicated in motor skill learning.
    International Journal of Imaging Systems and Technology 01/2008; 18(1):69-78. DOI:10.1002/ima.20139 · 1.30 Impact Factor
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