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Wan-Qing Yu, Eun-Jin Lee, Greg Field, Norberto Grzywacz; Changes of Receptive Field Properties of Ganglion Cells in a Rat Model of Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6198.
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© ARVO (1962-2015); The Authors (2016-present)
In some models of Retinitis Pigmentosa (RP), cone mosaics undergo rearrangement following the death of rods. In S334ter-line3 rats, cones migrate out of a semi-regular lattice to form ring-like patterns. However, light responses of retinal ganglion cells (RGCs) persist after cone migration. Our study identified the consequences of cone reorganization on the receptive fields (RFs) of RGCs. In particular, RGCs located in the center of cone rings may have a minimal light response if the cones are disconnected. Alternatively, these RGCs may exhibit a displaced RF with a Gaussian shape if the RGC reconnects (via bipolar cells) to cones in the rings. Finally, RGC RFs may exhibit arch-like shapes if RGCs maintain their original connections as the cones migrate. To resolve these possibilities, we measured RFs at high resolution across large populations (~300) of RGCs in normal and RP retinas.
Extracellular recordings were made from P60 Long Evans and heterozygous S334ter-line3 rat RGCs using a 512-electrode array. Spatiotemporal RFs were estimated as spike-triggered averages using binary white noise stimuli. Cones were labeled with PNA and confocal images were taken after the recordings.
Recordings from normal and RP retinas exhibited similar numbers of RGCs, suggesting that they were connected to the cone mosaic despite its reorganization. Most RGCs in RP rats showed non-Gaussian RFs, with arch- or star-like shapes. The abnormal RFs were observed across all types of RGCs. Gaps in light sensitivity of RGC RFs matched the ring-like organization of the cones.
RGCs continue to function after the cone rearrangement in RP retinas. However, not surprisingly, RFs are abnormal. This suggests that RGCs do not disconnect from the cone mosaics as the cones migrate. Further, it suggests that bipolar dendrites or cone axons extend to maintain their contacts while the inner retinal circuitry is largely maintained.
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