Abstract
An alternative therapy for blinding diseases, such as retinitis pigmentosa and macular degeneration, is to confer light sensitivity on second and/or third order neurons in the retina. One benefit of this approach is it provides a therapy for late stages of retinal degeneration, where the majority of photoreceptors are already lost. We have delivered engineered light sensitive proteins to retinal ganglion cells in an animal model of retinal degeneration. These light sensitive proteins are capable of finely tuned control of single neuron activity in cultured hippocampal cells and retinal explants (Szobota et al. 2007, Borges and Greenberg, unpublished data) However, an important question is—How might engineered visual input be interpreted by the brain? To answer this question we have recorded cell population responses in V1 when visual input is limited to engineered channel induced activity in the retina. Our data show that these “photo-switches” in the retina are capable of restoring cortical responses to full field light flashes in previously “blind” animals.