Photically-Activated Electroencephalogram: Research Tool in Psychiatry

Abstract

Psychiatrically screened volunteer subjects and psychiatric patients were studied during intermittent photic stimulation. In susceptible subjects the rhythmic light stimulus was found to induce a variable dysphoria. In psychiatric patients this could take the form of previously experienced symptoms. Maladjusted individuals seemed to show a greater response to photic stimulation at 20-30 flashes per sec. and exhibited a trend toward increased high harmonic response. A lower convulsive threshold was demonstrated in 4 patients with psychiatric disorder whose symptoms included attacks with motor manifestation and in 5 volunteers without history of epileptic seizures. An individual sensitivity to specific frequencies was demonstrated. The susceptibility of certain psychiatric patients to photic stimulation is discussed with reference to the clinical and eeg. manifestations of paroxysmal tendency.