A Cardiac Hypothesis for the Origin of EEG Alpha

Major hypotheses for the origin of EEG alpha suggest a neural basis, but omit to consider other electrical and mechanical aspects. A cardiac electromechanical hypothesis is proposed. This hypothesis suggests that the natural mechanical frequency of the skull-brain mass is approximately 10 Hz. This has been determined by model and direct measurement. Membrane, liquid junction, electrode, and static charges exist as nonneural sources of potential in EEG recording. These standing potentials can be modulated by pressure and movement. It is postulated that the arterial pulse shocks the brain mass into oscillation at its natural frequency modulating the nonneural potentials. The arterial pulse has a jitter as great as ±720 electrical degrees at 10 Hz and amplitude jitter of approximately ±10 mmHg. Because of cardiac jitter, the differential aspect of amplification, and mixing of waves in the skull, coherence of alpha with phase of the cardiac cycle could not be demonstrated. The cardiac electromechanical hypothesis may assist others in designing experiments that will establish a valid explanation for the origin of EEG alpha.