The slow wave component of retinal activity inrd/rdmice recorded with a multi-electrode array

We investigated the differences in the retinal activity between normal and degenerate retina. Multi-electrode recordings were performed in in vitro mice retinas. Only short duration (<2 ms) retinal spikes were recorded in normal mice by postnatal day 28. However, in rd/rd mice, a slow wave component with approximately 100 ms duration was also recorded along with the spikes. We attempted to understand the mechanism of this slow wave component in degenerate retina by applying various synaptic blockers. With CNQX/AP-7, the glutamate antagonist (n = 7), the slow wave component disappeared while the normally less-dominant retinal spikes became more apparent. With strychnine, the glycine antagonist (n = 3) or picrotoxin, GABA antagonist (n = 3), the amplitude of the slow wave component increased. These suggest that a stronger excitatory glutamate input from bipolar cells to ganglion cells is the main contributor to this slow wave component in rd/rd mice.