Foci of activity of the alpha rhythm in the human electro-encephalogram.

Abstract

Electrical potentials of the brain have been recorded simultaneously from adjacent areas along longitudinal and horizontal planes of the head in 16 subjects by means of 2 matched, independent amplifying and recording systems. A study of the simultaneous phase relationships of the a waves from adjacent areas revealed 4 regions in each cerebral hemisphere over which reversals of phase or foci of activity were found. 2 of the foci are located over the occipital region of the brain, a 3d over the ant. part of the parietal area and a 4th over the temporal region. Other indications that the a rhythm of each region has a separate origin were found in the independent variations in the pattern, magnitude and frequency of the a waves recorded simultaneously from different regions of the brain. The foci of activity are apparently associated with thalamo-cortical projections which exercise a controlling influence on the spontaneous rhythms of the cortex.