Journal of Neuroscience, Vol 7, 1056-1063, Copyright © 1987 by Society for Neuroscience
Background and bleaching equivalence in steady-state adaptation of vertebrate rods
KN Leibovic, JE Dowling and YY Kim
We have investigated background and bleaching adaptation in vertebrate rods
by intracellular recording in the retina of Bufo marinus. Backgrounds and
bleaching produce adaptation in photoreceptors and lead to a shift and a
compression of the response operating range. Threshold elevation due to
backgrounds follows the Rose-DeVries rule at low intensities and the
Weber-Fechner rule at high intensities. Threshold elevation due to
bleaching is linear almost up to 17% bleached pigment and exponential
thereafter. An equivalence can be established between bleaching and
backgrounds with respect to threshold elevation, on the one hand, and with
respect to response compression, on the other. These equivalences are the
same within experimental error. The equivalence, moreover, appears to
extend to the complete response curve. These results have implications for
psychophysics as well as for photoreceptor transduction.