Interaction of photoreceptor-driven signals in the mouse electroretinogram

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Vision is the most important sensory input for humans and blindness constitutes a major impact on the quality of life. It is therefore extremely important to understand the processes that lead to visual perception. Vision starts through photon absorption in the photoreceptors and the visual processing starts at the first synapse where the information is distributed into different parallel pathways. The information from different photoreceptor types have distinct entrances into the post-receptoral retinal pathways that transmit the information to several brain areas where it is available for different visual performances including conscious visual perception. It is therefore important to study how the signals from single photoreceptor types are processed in the retina and how these signals interact post-receptorally. Currently, a thorough description of the interaction between rod- and cone-driven signals in the intact mouse in vivo is, however, lacking. In the proposed project, the different types of interactions will be investigated.In previous studies, we have characterized the influence of temporal frequency, contrast, mean retinal illuminance and mean chromaticity on the electroretinographical (ERG) signals originating in rods and cones in mice using the silent substitution paradigm. To be able to obtain a signal with satisfactory signal to noise ratio, we used the so-called LIAIS mouse where the native M-cone pigment is replaced by the human L-cone pigment. Otherwise, these mice are anatomically and physiologically normal. The use of the LIAIS mouse and the silent substitution paradigm enables extending the studies aiming at the interactions between rod and cone-driven signals in vivo and in the intact organism (i.e. with fully functioning photoreceptors and post-receptoral mechanisms including intact cross-connections between the different cell types and cell circuitries). Different types of interactions will be studied.