alpha coherence
Research Papers
Symbol Digit and the Quantitative EEG
The coordination of allocation resource model of brain functioning examines the relations between quantitative EEG (QEEG) variables and cognitive performance on specific tasks. The Digit Symbol (DS) subtest of the Wechsler Adult Intelligence Scales has proven to be a sensitive measure in a variety of clinical conditions. A conceptually and empirically similar task (Symbol Digit [SD]) was employed to examine the QEEG correlates of successful functioning. A sample of 119 participants engaged in a modified SD test for 200 seconds while QEEG data were obtained. The participant verbally provided the matching number to the examiner to avoid any motor component of the task. There were negative relations between performance and magnitudes across almost all locations and across a wide bandwidth (0-64 Hz). Negative relations to SD performance were also observed for increased relative power of beta1, whereas positive relations were found for absolute values of coherences of alpha, beta1 (13-32 Hz), and beta2 (32-64 Hz). The results showed the importance of spectral correlation coefficients (SCC) in cognitive functioning, in particular the SCC values within the frontal region and in the 13-64 frequency range.
View Full Paper →Improvements in Spelling after QEEG-based Neurofeedback in Dyslexia: A Randomized Controlled Treatment Study
Phonological theories of dyslexia assume a specific deficit in representation, storage and recall of phonemes. Various brain imaging techniques, including qEEG, point to the importance of a range of areas, predominantly the left hemispheric temporal areas. This study attempted to reduce reading and spelling deficits in children who are dyslexic by means of neurofeedback training based on neurophysiological differences between the participants and gender and age matched controls. Nineteen children were randomized into an experimental group receiving qEEG based neurofeedback (n = 10) and a control group (n = 9). Both groups also received remedial teaching. The experimental group improved considerably in spelling (Cohen’s d = 3). No improvement was found in reading. An indepth study of the changes in the qEEG power and coherence protocols evidenced no fronto-central changes, which is in line with the absence of reading improvements. A significant increase of alpha coherence was found, which may be an indication that attentional processes account for the improvement in spelling. Consideration of subtypes of dyslexia may refine the results of future studies.
View Full Paper →Alpha Suppression and Symmetry Training for Generalized Anxiety Symptoms
Twenty-eight anxious adults were assessed for frontal lobe alpha asymmetry, a brain state associated with depression and anxiety. Fifteen of the 28 exhibited significant asymmetry and 12 agreed to participate in a biofeedback program addressed at reducing frontal alpha asymmetry. Method. The program consisted of earlobe temperature biofeedback (ETB) and two forms of neurofeedback, alpha suppression and alpha symmetry training. Individuals were instructed to warm their right earlobe for six sessions, and half succeeded, though success was not required to advance to the next stage of training. For subsequent EEG training, two anterior sites were selected on the basis of poor alpha coherence. Individuals were trained to reduce alpha magnitude at these sites by 10% for 30 min or more, which took from 6 to 16 sessions to achieve. Once successful with alpha suppression, individuals were trained to improve alpha symmetry between the sites by 15% for 30 min or more. Results. This feat took 8 to 32 sessions to achieve, and eventually all eight individuals were able to reduce alpha asymmetry. The State-Trait Anxiety Inventory (STAI) was used to measured anxiety levels after each training type and both state and trait scores significantly improved by a 6-month follow-up. Conclusion. Participants also completed a daily shortened version of the STAI, which indicated that anxiety improved after neurofeedback but not after ETB.
View Full Paper →Electrophysiology of Auditory Memory of Paragraphs Towards a Projection/Activation Theory of the Mind
Introduction: An investigation into the QEEG parameters of effective auditory memory for paragraphs was conducted employing sixty normal right-handed subjects. Method: Four stories were read to the subjects. The subjects engaged in an immediate thirty-second quiet recall period, which was followed by the subjects recalling the stories outloud. A delayed recalled assessment (about forty-five minutes) followed the same methodology. Results: The recall performances were correlated with the QEEG variables. For the input period the absolute levels of the Alpha coherence and phase generators from the left temporal lobe (T3), as well as the coherence Alpha (C3, P3, F7) were the predominant determinants of success in addition to F7 coherence Betal (13-32 Hz) and phase Betal from F8. Immediate recall was determined by the absolute levels of the projections from T3 (coherence and phase Alpha), symmetry Beta2 (32-64 Hz) at T3 and peak frequency of Betal at T5. Long-term recall was determined by the T3 generators (phase and coherence Alpha), F7 projections (phase Theta, coherence and phase Alpha, phase Betal, coherence Beta2), Fpl and F3 projections (coherence Beta2), and Fpl phase Betal. Degree of activation (from eyes closed) revealed additional variables relevant to success. Discussion: These research results are integrated into previous neuroscience research and implications for theories of brain function and neurotherapy applications are discussed.
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