Abstract
The supernormal electrical excitability of the eye following an pre-illumination is reduced or abolished by the second light applied prior to the test of electrical excitability, and this phenomenon is called retinal in-hibition.
1. Retinal inhibition must be an physiological event occurring at the retina because the modifying light applied to the contralateral eye which has not been pre-illuminated, has only a slight inhibitory action upon the retinal process occurring in the ipsilateral eye, compared with the same stimulus applied to the ipsilateral eye which has been pre-illuminated. The mode of action of the light applied to the contralateral eye is not selec-tive, but all the retinal processes are equally inhibited by it.
2. The degree of retinal inhibition increases linearly with the loga-rithm of the intensity of the modifying light within the middle range of intensities.
3. Retinal inhibition depends also upon the intensity of the pre-illu-minating light; Generally the higher the intensity the more marked the retinal inhibition. The reversal of effects or facilitation occurs when the intensity is lower than a certain definite level. Such facilitation is never found when the modifying light is applied to the contralateral eye.
4. The wave-length dependence of the inhibitory effects of spectral lights upon each retinal process is closely similar to the physiological sensa-tion curve reported by Motokawa.
5. The mechanism of retinal inhibition and facilitation is discussed.
