An electroencephalographic study for clarifying psychophysiological brain functions

Abstract

(1) This report concerns with the experiments in which EEG being neurophysiological in nature was used as an index of the psychophysiological activities, and it was attempted to obtain a mode of the brain activity and a significance of α rhythms. A part of the role of sensory perception playing in constructing mental process was also studied. (2) Occipital EEG of α dominant man in the sitting position was comparatively investigated when he was at rest, stimulated visually by pictures or letters, or stimulated by visual imagination of which real figure for recalling was seen a few minutes before. Considering from the experimental results, EEG was possible to be an index of psychological processes to some degree. (3) Response of occipital EEG to recalling the visual image of which content was really seen a few minutes before was α acceleration. The continuance of the acceleration was probably dependent upon the capability to maintain the image in mind. No α blocking was usually present after this type of stimulation. (4) Concurrently, β activity was increased and θ activity was frequently decreased, suggesting that the α acceleration was a response specific for visual imagination. When imagination was repeated with adequate intervals the response of α acceleration was taken place on all such occasions. (5) Only acoustic stimulus which commanded to make internal image, the image being not really made at that time, resulted in α blocking or no change but evidently not in α acceleration. Menthol application suggested that the mesencephalic reticular formation might not contribute to the α acceleration. (6) The α acceleration was supposed as an increase in grade of synchronization in the electro-oscillatory neuronal network in the visual or visual association area, an the synchronization might be a simple response of the network to the increase in frequency of circulating impulses. (7) Brain function was considered by EEG from its operational sideview. Alpha acceleration, one kind of synchronization, was interpreted standing on an idea that α waves scan visual signals. The role of sensory stimulus playing in establishing the internal perceptive world was partly discussed, and its contributionto maintenance of vivid mental process was also suggested. © 1973, Kurume University School of Medicine. All rights reserved.