Rod-cone independence for sensitizing interaction in the human retina.

1. Illumination of a retinal area adjoining a tested area can cause either desensitization or sensitization through lateral interaction, depending on whether the distance separating the illuminated and tested areas is small or large. This interaction occurs both in the rod and the cone mechanisms of the retina when each is tested separately by selection of appropriate adapting and testing stimuli.2. In the mixed rod/cone region of the near periphery of the human retina the spatial parameters of interaction within the rod and cone systems were different when mapped out by using only one kind of adapting stimulus and sampling the excitatory state of the rod and cone systems by different probing stimuli.3. Sensitizing interaction signals generated by the rod system are incapable of causing sensitization of the cone system.