Influence of pattern and red color on the photoconvulsive response and the photic driving

Patients, 232 epileptics and 98 nonepileptics, were examined for photoconvulsive responses and photic driving, by using a stroboscope with a) a printed pattern (dots or grating) and b) a red plastic plate. The stimuli given were (1) dot pattern 5 Hz IPS, (2) red 5 Hz IPS, (3) grating pattern 15 Hz IPS, and (4) red 15 Hz IPS, with eyes open. Photoconvulsive responses evoked by (3) and (4) were 6.6% and 5.1%, respectively, which were significantly higher than those obtained from a control group flickered with ordinary white light, 15 Hz IPS, (1.1% and 0.9%, with eyes open and closed, respectively). High amplitude photic driving over 50 microV evoked by (1) occurred in 34.9% of the patients and by (2) 22.7%; these were significantly higher than in the control group with ordinary white flicker (12.5% and 5.2%). Similar stimuli of (1) to (4) with a constant brightness of 20 cd/m2 provided by a visual stimulator SLS-5100 were given in the same way. Photoconvulsive response evoked by 15 Hz flickering grating pattern occurred in 7.8% and by 15 Hz red flicker in 8.1%; the rate being slightly higher than, but not significantly different from, the above results. High amplitude photic driving evoked by 5 Hz flickering dot pattern and 5 Hz red flicker were 29.3% and 21.2%, respectively. These values were slightly lower than, but not significantly different from, the above results. It was concluded that the flicker stimulation with either pattern or red color is more potent in eliciting photoconvulsive responses (15 Hz) and photic driving responses (5 Hz) than conventional flicker. Furthermore, patterned IPS and red IPS showed almost the same activation effect on photoconvulsive responses and high amplitude photic driving as that of the comparable stimuli provided by a visual stimulator SLS-5100.