Axonal conduction velocity was affected by the absence of R-Ras1 and/or R-Ras2. A, Experimental design. Alert-behaving mice received a photic stimulator (flash) through a stroboscope located 30 cm in from of them. B, Recording electrodes implanted in the left dorsal lateral geniculate nucleus. Photomicrograph illustrates recording electrode location. C, Examples of field potentials evoked by light flash stimulation at the dorsal lateral geniculate nucleus. Recordings averaged 20 times and collected from representative control, R-Ras1^−/−, R-Ras2^−/−, and R-Ras1^−/−;R-Ras2^−/− mice. Light flash presentation is indicated by an arrow. Latency to P1 and to the latest N component of the evoked field potential are indicated. D, E, Although no significant differences were observed for latency values from flash presentation to P1, latency values to the last N component of the evoked field potential were significantly larger for the three experimental groups (R-Ras1^−/−, R-Ras2^−/−, and R-Ras1^−/−;R-Ras2^−/−) compared with controls. ***p < 0.001. All mice analyzed were adults (P120).