Habituation of the nictitating membrane reflex response in the intact frog.

Habituation of the nictitating membrane reflex response was measured in the intact bullfrog. A stimulus map was created, and stimulating electrode pairs directly opposed across the eye proved to be the optimal loci for cutaneous electrical stimulation. The response was found to exhibit all of the parametric characteristics of habituation. To date, this represents what is perhaps the simplest intact vertebrate preparation demonstrating habituation. The response was also found to exhibit a surprising periodicity in response amplitude when unchanging stimuli were infrequently presented over long periods of time. The convenience, reliability and successful behavioral assessment strongly recommend this preparation as an ideal simple vertebrate model system for further examination of the neural basis of behavioral plasticity.