[Electroretinographic study on the causal relationship of the S-R effect]

In the continuation of earlier studies, further serial-stimulation experiments with prolonged duration of single stimuli were carried out on dark-adapted frogs. The results have revealed a far-going dependence of the retinal response patterns (S-R effect) on the time relations between single stimuli and stimulation intervals. From all the experimental evidence available to date it can be concluded that the demonstrated serial-stimulation effects are brought about primarily in the photorecptors. According to reports in the literature these receptors in the state of dark adaptation respond to intensive, overriding stimuli with a pronounced after-effect causing a reduction of the temporal resolution capacity and of the difference susceptibility. The suppression effect can be regarded as a consequence of this overriding reaction. On the other hand, the recovery effect is caused most probably by the suddenly occurring bright adaptation because the latter makes the after-effect disappear quickly.