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S. He, W. Sun, Q. Deng; ON Direction–Selective Ganglion Cells in the Mouse Retina . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2335.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To explore the physiology, pharmacology, and morphology of ON direction–selective ganglion cells (DSGCs). Methods: C57BL/6N mice were deeply anesthetized, enucleated and euthanized. Retinas were quickly isolated. Light responses from ON DSGCs were recorded in loose–patch and whole–cell voltage–clamp mode in dark adapted, whole mount mouse retina. Both spike responses and excitatory and inhibitory current were studied. Morphology of recorded cells was recovered by visualizing Neurobiotin. Results: ON DSGCs responded to a stationary flashing spot with sustained spiking. Strong directional selectivity was revealed using a moving rectangle. Voltage clamp recording showed that these cells received a larger inhibitory input when the stimulus was moving in the null direction and a larger excitatory input when stimulus was moving in the preferred direction. Visualization of neurobiotin revealed a large, monostratified dendritic field with recursive dendrites forming loop–like structures. This type of RGCs was previously identified as RGC1 by morphological properties. Curiously, we observed a clear OFF component on the ON DSGCs. This OFF component consisted of a small excitatory input and a large inhibitory input. Extending the length of the moving rectagle delayed both OFF excitation and inhibition, also, application of ON channel blocker, APB abolished both ON excitation and inhibition, whereas the OFF excitation and inhibition remained intact. Conclusions: This study illustrated the synaptic mechanism for computing motion direction of ON DSGCs, and revealed a curious OFF signal in the ON channel.
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