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. Author manuscript; available in PMC: 2008 Jun 21.
Published in final edited form as: Eur J Neurosci. 2003 May;17(9):1727–1735. doi: 10.1046/j.1460-9568.2003.02594.x

FIG. 4.

FIG. 4

Intrinsic light responses of SCN-projecting RGCs. During recordings, cells were exposed to a 20-s step of white light from a tungsten-halogen lamp (bar). (A) In current-clamp, the cells responded to light (5.8 × 10−5W/cm2) with a slow depolarization which generated increased spiking activity. (B) In contrast the resting membrane activity of unlabelled ganglion cells, chosen at random, did not show any response to the same light stimulus (top two traces). No light responses were observed from RGCs labelled by an optic nerve hit (lower trace). (C) The responses of an SCN-projecting RGC to increasingly brighter illumination. The numbers below each trace represent the light intensity of the stimulus in W/cm2. (D) The relationship between stimulus intensity and spike frequency was approximately linear over the range of light intensities used.