Abstract
Using unanesthetized rabbits, the ERG (b-wave) and cortical potential evoked by intermittent photic stimulations (0.5-15 f/sec) were recorded simultaneously to obtain the retinal and cortical (visual cortex) frequency response activities.
Despite many variations in each case, the following general tendency was recognized. The maximum amplitude of both the average cortical and retinal responses was elicited by flash stimulation of the lowest frequency (0.5-1 f/sec). Though the amplitude of both average potentials decreased gradually with increasing flash frequencies, the cortical response was enhanced at 3 and 5 f/sec resulting in two humps in the cortical frequency response. They corresponded to the dominant peaks in the frequency spectra of the spontaneous brain wave.
Notwithstanding many variations in the responses in relation to the flash intensity, the stimulus with stronger intensity elicited generally a response of larger amplitude. With increasing flash frequency, the effects of intensity became less in the cortex than in the retina. These results are discussed from the stand point of the EEG “ activity ”(which has been considered to be an extension of “ excitability ”).
