This parallel light converges to excite the group of photoreceptors sharing the same visual axis. In order to stimulate photoreceptors individually, the low aperture light beam diameter is reduced such that it is not exceeding one facet. Only one photoreceptor is stimulated using this small light beam. In order to identify the stimulated photoreceptor, we use the identification technique we developed last year. If we take a picture of the eye at this moment, we observe that a group of eight facets are brighter.
Results shows that several nonlinear features have been found.
Decrease of the peak potential Transmission time delay Different response from neighboring photoreceptors stimulation. Since there is an electrical coupling between photoreceptors, the light stimulation of a given photoreceptor produces an electrical current into the neighboring photoreceptors. Some of these nonlinear features suggest that a voltage dependent conductance influences the signal transmission. Indeed, we found that a voltage dependent potassium channel in the soma photoreceptor has been identified. This voltage dependent channel allows us to predict the shape of neighboring photoreceptors response.