The Brain As Generator Of Transcephalically Measured Direct Current Potentials.

The transcephalic direct current potentials are slowly changing voltages measured between specified diploic-emissary vein distributions on the intact surface of the scalp. Significant correlations have been found between these voltages and various psychological functions which appear consistent with the functional properties of the subjacent cortex. In an effort to specify the location of the source of these potentials, virtually every conceivable voltage generating tissue and structure of the head was studied for its dc voltage effects both under maximal stimulation and maximal inhibition (i.e. surgical ablation or chemical inactivation). Structures studied were: the various layers of the scalp itself; scalp sweat glands; the nervous and vascular supply of the scalp: the structures of the orbit; the muscular distribution of the head: the skull: the meninges; and finally the vascular supply of the cortex and the cortex itself. It was found that no structure played any significant dc generating role except the cortex. It was also possible to demonstrate a cortex to scalp circuit pathway which runs principally within a centrifugally running intravascular system. It appears warranted to conclude that transcephalically measured direct current potentials are generated by the cortex. [ABSTRACT FROM AUTHOR]