Peripheral Flicker Fusion in Psychiatric Patients with EEG Abnormality

Abstract

An apparatus was developed for measuring peripheral CFF under low levels of illumination rendering the stimuli functionally invisible when centrally fixated. The responses of 27 psychiatric patients with EEG abnormalities were compared with 34 control patients with normal EEGs. One-third of the abnormal Ss had right field-left field CFF discrepancy scores greater than all but one of the control Ss. This experimental sample included 4 Ss with lateralized left-hemisphere EEG defect. However, CFF impairment in these Ss was most pronounced in the left visual field (right cerebral hemisphere). This suggested the possibility that instead of a sensory defect the primary defect may have been one of verbal labelling with maximal impairment occurring under interhemispheric test conditions. That is, verbal labelling of sensory events (a left hemisphere function) may have been differentially impaired for contralateral as opposed to ipsalateral CFF stimulation.