Cross-correlation of human alpha activity: normative data.

Abstract 1. 1. Forty-two asymptomatic adult males were studied by history, physical examination and EEG. Cross-correlograms were generated from the EEG data derived from P 3 -O 1 and P 4 -O 2 . 2. 2. Twenty-four subjects exhibited phase lead to the right and eighteen to the left. None were exactly in zero phase. 3. 3. Average phase shift for the group was 0.83 msec to the right. 4. 4. The range of the phase shifts was from 4 msec left to 7 msec right. 5. 5. This report emphasizes that not all normal subjects are essentially synchronized with respect to their alpha activity, although in most normals there is clearly some imperfect neurological mechanism operating to phase align the alpha activity. 6. 6. In a number of normal subjets a surprising degree of right-sided alpha phase leading was seen; a degree not approached in those subjects in which left-sided alpha activity was phase leading. 7. 7. These findings tend to support textboo statements that cerebral dominance for alpha rhythm more often resides in the right hemisphere of normal humans in the sense that it more often exerts an average phase lead over the alpha activity generated in the left hemisphere.