The starting point of vision is the detection of light by the retina and more specifically the absorption of light by photoreceptors cells photopigment. In these cells, light is transformed into an electrophysiological signal by a process named phototransduction. This electrophysiological signal, after going through the retina and the optic nerve, reaches the brain and is integrated. Surprisingly, although visual sensory impairments were described in Mental Deficiency and Autism Spectrum Disorders, no data had been collected on light Atipamezole HCl perception at the retinal level even if the retina is a neural tissue with the same embryonic origin as diencephalon. It is even more interesting since our experiments showed that Fmrp is expressed in the WT retina. Therefore, we hypothesized that a lack of Fmrp could induced similar cellular and functional defects in the retina as it does in cerebral neurons. Retinal function, recorded by ElectroRetinoGram, is defined by all the electrophysiological manifestations between Rhodopsin activation by light and the electrophysiological message sent through the optic nerve to the brain. As expected, Fmr1 KO mice showed altered ERG recordings characterized by a decrease in the a and b waves, and an increase in the slope of the Cefetamet pivoxil HCl b-wave sensitivity curve. These data indicate retinal impairments in Fmr1 KO mice. Because the Bmax/Amax ratio was similar between Fmr1 KO and WT mice, we can assume that the b-wave decrease and so the amplitude of the signal transmitted from the photoreceptors to the inner retina is mainly due to the decrease of the a-wave. In addition, a-wave reduction was not due to a loss of photoreceptors, since the ONL thickness was similar between Fmr1 KO and WT mice, but linked to decreased in Rhodopsin content as shown by Western-blot and spectrophotometric analysis. Indeed, Rhodopsin is the specific rod-photoreceptor protein responsible for the first events in the perception of light, and its concentration is directly correlated to a-wave amplitude. Rhodopsin activation by light and the electrophysiological message sent through the optic nerve to the brain.