Meeting Abstract

61.2  Thursday, Jan. 6  Electrophysiology of the snake retina KOHL, T.; YOUNG, B.A.*; Univ. of Bonn; Univ. of Massachusetts Lowell Bruce_Young@uml.edu

Few previous studies have explored the snake’s eye from a functional perspective. We recorded electroretinograms (ERGs) from a number of snake species chosen following considerations of phylogeny, habitat, and temporal activity patterns. For each species we determined the flicker-fusion frequency, a contrast sensitivity profile, and an intensity response curve. The flicker-fusion frequencies spanned from 15 – 60 Hz and closely correlated with activity patterns; diurnal species which appeared to be visually-dominant had the highest flicker-fusion frequencies. The normalized contrast sensitivity profiles had an interspecific range of nearly 40% at every contrast level, with the more visually-dominant taxa on the lower end of the normalized response. Nearly half of the species had a continuous increase in response with increasing stimulus contrast; the other half had response peaks below maximal contrast. The normalized intensity response curves had the most interspecific variation. Most of the species displayed a bimodal intensity response, in some cases with more than a 50% difference in response between the high and low intensity response. We suspect that the interspecific variation we document in retinal electrophysiology is a reflection of, among other factors, differences in photoreceptor compositions among the retinas of the different species.