In the preceding letter (Pepperberg 2001), Dr. David Pepperberg offers an alternative interpretation to that given in our recent paper (Nikonov et al. 2000) for the nature of the changes underlying light adaptation in rod photoreceptors. We do not agree with Dr. Pepperberg's interpretation, and we set out our reasons below. From the outset, we should make it clear that we and Dr. Pepperberg are measuring different phenomena: our analysis concentrated primarily on the rising phase of the response (both to dim and bright flashes), whereas Dr. Pepperberg's analysis concentrates on the recovery phase of the response to bright flashes. This difference has important consequences for the interpretation of mechanisms.
Dr. Pepperberg refers to the “relative gain” g of transduction, estimated from the time during which the photoreceptor remains in saturation after exposure to an...
