CO[sub2] and the Cephalic Direct Current System: Studies on Humans and a Biophysical Analysis.

The TCDC/CO, hypothesis is that slowly changing potentials, source resistances and source currents, measured between electrodes placed over specific diploic/emissary vein distributions on the scalp, largely reflect regional differences in subelectrode CO[sub2] concentrations which are in equilibrium with subjacent conical differences in metabolism and CO[sub2] production. Studies on humans show that TCDC parameters do show the expected relationships with the effects of regional differences in CO[sub2] concentration. An explicit quantitative formulation of the hypothesis is developed based on the best available measures of all essential parameters, and it is shown that this model permits the correct computation of all TCDC empirical norms under essentially all conditions of measurement. Although it now appears that TCDC studies have a substantial theoretical foundation it must be emphasized that the analysis in this paper is based on normative -- i.e. averaged -- values and cannot yet be applied to isolated TCDC measurements on single subjects. [ABSTRACT FROM AUTHOR]