Journal of Neuroscience, Vol 8, 4621-4627, Copyright © 1988 by Society for Neuroscience
A behavioral analysis of habituation and sensitization of shortening in the semi-intact leech
NM Boulis and CL Sahley
Department of Biology, Yale University, New Haven, Connecticut 06511.
We have previously demonstrated that the shortening reflex of the leech
Hirudo medicinalis displays habituation, dishabituation, and sensitization.
In this paper we demonstrate that the shortening reflex of the semi-intact
animal also displays these phenomena. In the first experiment we found that
the magnitude of the touch-elicited shortening reflex decreased as a result
of repeated stimulations of the skin every 2 min. The second experiment
examined the change in this reflex as a function of the interstimulus
interval (ISI). The reflex failed to decrease when the ISI was 10 sec, but
decreased significantly when the ISI was either 45 or 360 sec. Finally, in
a third experiment we found that the presentation of noxious stimuli prior
to habituation training prevented habituation. Thus, as we have observed
previously in the intact animal, the semi-intact animal displays
habituation, dishabituation, and sensitization.