Cosyne 2008 Workshops
March 3-4, 2008
Snow Bird, Utah
Speaker Name
Botond Roska
Talk Title
Rescuing visual sensitivity by cell type specific expression of ChR2 in retinal ON bipolar cells
Talk Abstract
The recent advent of genetically encoded optical neuromodulators creates the opportunity for circuit-specific intervention in neurological diseases. One of the diseases most amenable to this approach is retinal degeneration (rd), where the progressive loss of photoreceptors leads to complete blindness. Here we genetically target a light-activated cation channel, channelrhodopsin-2 (ChR2), selectively to second-order neurons, ON bipolar cells, of degenerated retinas in vivo. We show that in the absence of "classical" photoreceptors, photosensitive ON bipolar cells induce light-evoked spiking activity in ganglion cells. The rescue of light sensitivity is selective - only circuits that signal light increments are functional. Similar to healthy retinas, parallel processing in the time domain and modification of the information flow by inhibitory circuitry are demonstrated. Despite the lack of outer retinal processing, ganglion cell receptive fields have centre-surround organization. Transmission of the light signals to the visual cortex and light-induced behavioural changes were also observed.
