MOTION DETECTION IN GOLDFISH INVESTIGATED WITH THE OPTOMOTOR RESPONSEIS COLOR-BLIND

The action spectrum of the optomotor response in goldfish was measured to investigate which of the four cone types involved in color vision contributes to motion detection, In the dark-adapted state, the action spectrum showed a single maximum in the range of 500-520 nm, and rese mbled the rod spectral sensitivity function. Surprisingly, the action spectrum measured in the light-adapted state also revealed a single ma ximum only, located in the long wavelength range between 620 and 660 n m, A comparison with spectral sensitivity functions of the four cone t ypes suggests that motion detection is dominated by the L-cone type, U sing a two colored, ''red-green'' cylinder illuminated with two monoch romatic lights separately adjustable in intensity, it could be shown t hat motion vision is ''color-blind'': the optomotor response disappear ed whenever ''isoluminant'' red and green stripes were offered. Under this condition, calculations revealed that the L-cones were only sligh tly modulated by the ''red-green'' stimulus. Copyright (C) 1996 Elsevi er Science Ltd.