High Amplitude Photic Driving evoked by Flickering‐Pattern in Neuropsychiatric Patients — With Special Reference to Epileptics

In the previous studies: it was shown that when high amplitude photic driving (PD) is evoked by 5 Hz flickering-dotpattern (FDP) in adult patients, functional disorders of the visual cortex are suggested. The present study was therefore undertaken to determine the incidences of high amplitude PD in various neuropsychiatric patients. A total of 543 patients were examined. They were epilepsy (3 19), schizophrenia (43), affective disorders (27), neuroses (41) and other disorders (113). Ages ranged from 21 to 76 years, with a mean age of 34.5 years. Of these 543 patients, 291 (54%) were male and 252 (46%) were .female. A visual stimulator SLS-5100 (Nihon Kohden) was used to perform FDP stimulation. FDP stimulation was given to each subject in a sitting position. The apparatus yielded an approximately sine-wave output for flicker stimulation. After 2 to 3 minutes of dark adaptation, the subjects were instructed to look through a window at the central regions of a tangent screen set 25 cm from the eyes, and the stimulation was projected onto the screen (25 X 25 cm). When the pattern was projected onto the screen, the visual angle of a single dot was 1.33 degrees. Such 5 Hz FDP stimulation was given to each subject for 7 seconds. The amplitude of the PD was defined as that of the largest 5 H z PD evoked in the