SOURCE LOCALIZATION OF BRAIN ELECTRIC-FIELD FREQUENCY BANDS DURING CONSCIOUS, SPONTANEOUS, VISUAL-IMAGERY AND ABSTRACT THOUGHT

This paper addresses the issue of mind-brain correspondence, using a n ovel way to reduce brain electric field data in the frequency domain t o estimates of intracerebral model source locations, and applying this method to brain electric data collected during the 2-s epochs immedia tely before the randomly solicited reports of spontaneous, conscious, covert experiences from 12 normal volunteers. The mentation reports we re classified into visual imagery and abstract thought. The mean locat ions of the EEG model sources associated with abstract thoughts were g enerally more anterior and deeper than those of visual imagery, partic ularly significant for the delta/theta band; the finding was common ac ross subjects. Thus, different brain functional states involving diffe rent geometries of activated neural populations exist during conscious , spontaneous, task-free mentations of the visual imagery type and of the abstract thought type.