Alpha Activity Suppression and Enhancement as a Function of Feedback and Instructions

Abstract

The present study attempted to determine the role of instructions and feedback on alpha activity. Thirty‐six normal subjects were instructed to enhance or to suppress alpha activity or were given ambiguous instructions. Subjects were randomly assigned to three croups of 12 subjects earn. One‐half of the subjects in each group received feedback for increasing alpha activity, while the other half received feedback for suppression. Active and dummy electrodes were attached to each subject. Subjects were instructed to keep their eyes closed (luring the session. The session consisted of a 10‐min adaptation period, an instruction period, another 5‐min adaptation and then a series of 5 lest trials with feedback separated by 2‐min rest periods without feedback. Alpha enhancement was associated with instructions hut was independent of feedback. However, accurate instructions and feedback were associated with alpha activity suppression. Alpha activity was greatest during rest periods or when the subject was unaware of the significance of the feedback cue. which indicates the importance of monitoring basal levels of alpha activity in evaluating changes in alpha activity.

Alpha Neurofeedback Training for Performance Enhancement: Reviewing the Methodology

“…In terms of how long the session should last, there are no clear guidelines, and past research has utilized sessions that last from minutes to hours (e.g., Bauer, 1976;Nowlis & Kamiya, 1970;Prewett & Adams, 1976;Regestein, Pegram, Cook, & Bradley, 1973).…”

“…However, reward thresholds based on amplitude have ranged from 10 mV up to 218 JOURNAL OF NEUROTHERAPY 40 mV (e.g., Ancoli & Green, 1977;Hardt & Kamiya, 1976a;Holmes et al, 1980;Kuhlman & Klieger, 1975;Nowlis & Kamiya, 1970;Valle & DeGood, 1977) with some setting additional upper limits of 75 mV and 100 mV (Marshall & Bentler, 1976;Tyson, 1982). There is a similar level of variety when using thresholds based on a proportion of resting EEG activity, with thresholds set at between 50% and 85% of the amount of alpha seen when at rest (e.g., Cho et al, 2008;Cram, Kohlenberg, & Singer, 1977;Norris et al, 2001;Prewett & Adams, 1976;Travis et al, 1974Travis et al, , 1975. Clearly, identifying the chosen reward threshold would seem an essential aspect of NFT because it needs to be set at a level that ensures an adequate amount of feedback information is provided, allowing the learner to identify states, feelings, and cognitions that elicit the required activity.…”

“…The majority of unidirectional training has been aimed at encouraging participants to learn to enhance alpha (e.g., Angelakis et al, 2007;Bazanova et al, 2007;Cho et al, 2008;Fell et al, 2002), which some suggest is more preferable for participants than inhibiting it (Kamiya, 1969;Lynch et al, 1974). However, inhibiting alpha may be easier than enhancing it (Lynch & Paskewitz, 1971;Paskewitz & Orne, 1973;Peper & Mulholland, 1970;Prewett & Adams, 1976) although findings have been inconsistent (see, e.g., Regestein et al, 1973). Nevertheless, adopting a unidirectional approach that involves isolated training sessions either enhancing or inhibiting alpha may be less effective than a bidirectional training regime, which incorporates both enhancement and suppression, for at least two possible reasons.…”

“…However, identifying the specific frequency range of the alpha component of the EEG seems less certain. For example, previous attempts to enhance alpha using NFT have identified alpha as operating between 7-15 Hz (Brown, 1970), 7.5-13 Hz (Prewett & Adams, 1976), 8-12 Hz (e.g., Albert et al, 1974Cho et al, 2008;Fell et al, 2002), 8.5-12.5 Hz (Bauer, 1976), 8-13 Hz (e.g., Angelakis et al, 2007Hardt & Kamiya, 1978;Nowlis & Kamiya, 1970), 8.5-13.5 Hz (Valle & Levine, 1975), 8-14 Hz (Konareva, 2005, 2006, and 10 Hz AE 1 Hz (Drennen & O'Reilly, 1986). Such inconsistencies in identifying the frequency range of the training component not only make comparisons between studies problematic but also fail to take into account individual differences.…”

Modifications of the EEG frequency pattern in humans related to a single neurofeedback session

“…This problem, however, remains insufficiently studied [1,[4][5][6]. There is evidence that the necessity of trying to selfregulate EEG characteristics per se is capable of inducing the general suppression of the α rhythm [7]. It has been emphasized that the type of background rhythmics of the cerebral cortex in humans is rather stable [8], and this fact can be a fundamental obstacle for modifications of the EEG frequency composition.…”