Rheoencephalographic concomitants of cognitive engagement in nonpatients and schizophrenics. An exploratory study

Noninvasive cranial impedance plethysmographic, or rheoencephalography (REG), characteristics are reported to be well correlated with cerebral blood flow. This paper reports an exploratory study, in which we recorded REGs from four locations over each hemisphere in 16 nonpatients and 16 medicated schizophrenics under four conditions: eyes closed, eyes open, and following performance of the Seashore Rhythms and Wisconsin Sorting Tests. REG (Jacquy F index) values were greater anteriorly than posteriorly under all conditions. F index differed regionally between card sorting and eyes open conditions. With card sorting, F values of nonpatients increased more in the left than right hemisphere; schizophrenics showed the reverse hemispheric effect. Card sorting performance scores were positively correlated with regional F index changes in nonpatients, but not in schizophrenics. The results suggest that the REG may reflect regional cerebral effects associated with cognition and psychopathology.