EEG ASYMMETRY DURING MENTAL ARITHMETIC AND RECALLS OF VERBAL (KANJI, KANA, THE ALPHABET) AND VISUAL IMAGERIES

Abstract

EEG was recorded from the left and the right parietal areas in normal subjects with eyes-closed while they were engaged in mental arithmetic, recalls of verbal (Japanese kanji characters, kana syllabary, and the alphabet) and visual (scenery) imageries. Fourier analysis of EEG revealed attenuations of the alpha activity (a) in the left hemisphere during the mental arithmetic, (b) in the right hemisphere during the visual imagination of a scenery, and (c) in the both hemispheres during the kanji imagery accompanied by a stroke-count task. Results suggest that the kanji characters seem to activate cognitive processes of the both hemispheres. No attenuation of the alpha activity in the both hemispheres was seen during either the alphabet or kana syllabary imagery.