Enhanced sensory convergence to the visual cortex in the rodless (rd/rd) mouse.

The rd/rd mutation provokes a specific degeneration of the photoreceptive cells in the mouse retina, without affecting other neuronal elements. This degeneration starts 8 to 10 days after birth. Discriminative learning experiments have shown the degenerated retina to remain light-sensitive, the sensitivity being reduced to 10(-5) of normal with a peak still at 500 nm. An ontogenetic study showed a progressive vanishing of visual potentials (electroretinogram and visual evoked potentials) during the third week of life. Potentials of auditory origin, which can be recorded from the visual cortex in normal mice, were found to be clearly facilitated by the absence of the visual input either because of retinal degeneration in rd mouse or provoked by enucleation at birth.