Influence of color on the photoconvulsive response

Using the visual stimulator, the effect of color on the photoconvulsive response (PCR) was studied in 14 photosensitive patients. When stimuli of 15 c/sec flickers of white, red, yellow, green and blue light of 20 cd/m2 were given to the subjects, generalized PCRs were provoked only by the red-flicker. These PCRs were all inhibited by blue light of 1.9 cd/m2 when given either after the appearance of the PCRs or simultaneously with the red-flicker from the start. When blue light was given after the appearance of the PCRs the latency of appearance of the PCRs in response to the red-flicker showed an inverse relation to the disappearance latency of the PCR in response to the blue light. With blue light of 1 cd/m2, however, inhibition of the PCRs was seen in only 2 cases when it was given after the appearance of the PCR, and in only 1 case when the blue light was simultaneously given with the red-flicker from the start. These results clearly disclosed the following findings: (1) among various colored lights, an excitatory effect on generalized PCR was excitatory effect on generalized PCR was always seen only with red light at 15 c/sec and 20 cd/m2; (2) the PCRs provoked by the red-flicker were inhibited by blue light of 1.9 cd/m2, but not by blue light of 1 cd/m2.