Cortical alpha rhythm, biofeedback, and the determinants of subjective state.

Abstract

A critical assumption in the rationale for the clinical application of voluntary control over central nervous system (CNS) activity is that there exists a direct relationship between specific CNS activities and specific subjective mood states. The experiment reported here was based on the idea that a joint manipulation of both cognitive and physiological (i.e., alpha electroencephalographic [EEG]) variables would provide information required for an explication of the processes involved in subjective mood change. Three main variables were considered in the present experiment. First, the instructions were designed to induce a "set" or expectations for either positive or negative changes in subjective mood. Second, the type of feedback (alpha or not alpha) was varied. Those in the not-alpha feedback condition received feedback contingent on the absence of alpha activity, whereas those in the alpha feedback condition received feedback contingent on the presence of alpha activity. Third, an estimate of each individual's baseline alpha density was obtained, and on this basis subjects were classified as high-baseline or low-baseline subjects. Baseline alpha density, alpha density during training, and subjective mood were all considered as continuous variables. The results of the present study indicate that biofeedback of the cortical alpha rhythm is neither a sufficient nor a necessary condition for changes in subjective mood. In addition, the type of instructions designed to set subjects for positive or negative alterations in subjective states is predictive of changes in subjective state reported during alpha biofeedback training as well as of success at controlling and changing EEG during feedback training. The data presented here permit a direct examination of the actual relationship of EEG changes to changes in subjective mood state. Similar shifts in subjective mood state can be obtained with either increases or decreases in alpha activity. Further, both positive and negative subjective experiences can be associated with increases in alpha activity.

Stress management techniques: Are they all equivalent, or do they have specific effects?

“…This is consistent with the specific effects theory only if EEG activity reflects cognitive, more than somatic, arousal. Biofeedback-produced increases in EEG alpha and theta have been described in terms of state of consciousness: "relaxed" Staples et al (1975) PR, EMG bfk > AT EMG Schneider et al (1987) EMG bfk > AT EMG Gamble and Elder (1983) EMG bfk > TBFK EMG Reading (1983) EMG bfk > TBFK, SC bfk EMG Gamble and Elder (1983) TBFK > EMG bfk, PR AT > PR Blanchard et al (1988b) PR > TBFK alertness for alpha (Brown, 1970;Kamiya, 1969) and somnolescence for theta (Bell, 1979); however, others have raised questions about the relationship between biofeedback-induced changes in EEG rhythms and any specific mood or cognitive states (Beyerstein, 1990;Cott et al, 1981;Plotkin, 1979).…”

Identifying Indices of Learning for Alpha Neurofeedback Training

“…A review of the literature reveals that the three most common measures used to identify changes in alpha activity are percent time (e.g., Angelakis et al 2007;Cott et al 1981aCott et al , 1981bYamaguchi 1980) amplitude (e.g., Cho et al 2008;Putnam 2000) and integrated alpha (e.g., Knox 1982;Plotkin and Rice 1981;Tyson 1987). Percent time refers to the percentage of time participants spend above or below the target threshold when attempting to enhance and/or inhibit their alpha.…”

The Effect of Neurofeedback and Cranial Electrotherapy on Immune Function Within a Group of HIV+ Subjects: A Controlled Study

“…Similar shifts in subjective mood can be obtained with either increased or decreased alpha activity (Cott et al, 1981). There may be a threshold for benefit attained by increasing amplitude of low-frequency activity.…”

“…Training did not reward slower (i.e., theta, 4-6 Hz) frequencies, which instead of quiet attention indicate potential pathology or patterns of extreme drowsiness (Johnson, Seales, Naitoh, Church, & Sinclair, 1979). To minimize placebo bias (Cott, Pavloski, & Goldman, 1981), subjects were not informed of subjective or immune benefits they might derive from training.…”