The Journal of Neuroscience, October 15, 1998, 18(20):8467-8472
Prepulse Inhibition of the Tritonia Escape Swim
Donna L.
Mongeluzi,
Travis A.
Hoppe, and
William N.
Frost
Department of Neurobiology and Anatomy, The University of Texas
Medical School at Houston, Houston, Texas 77225
Presenting a weak stimulus just before a strong, startle stimulus
reduces the amplitude of the ensuing startle response in humans and
other vertebrates. This phenomenon, termed "prepulse inhibition"
(PPI), appears to function to reduce distraction while processing
sensory input. To date, no detailed neural mechanism has been described
for PPI. Here we demonstrate PPI in the marine mollusk Tritonia
diomedea, which has a nervous system highly suitable for cellular
analyses. We found that a 100 msec vibrotactile prepulse prevented the
animal's escape swim response to a closely following 1 sec tail shock.
This inhibition was highly transient, with a significant effect lasting
just 2.5 sec. These findings indicate that the Tritonia
escape swim response undergoes a form of PPI phenomenologically similar
to that observed in vertebrates. Further tests showed that the
vibrotactile stimulus had no inhibitory effect if applied after tail
shock, while the animal was preparing to swim, but it acted to
terminate swims once they were actively under way. As a first step
toward a cellular analysis of PPI, we recorded from neurons of the swim
circuit in a semi-intact preparation and found that the vibrotactile
stimulus used in the behavioral experiments also prevented the tail
shock-elicited swim motor program. These results represent the first
explicit demonstration of PPI in an invertebrate and establish
Tritonia as a model system for analyzing its physiological
basis.
Key words:
prepulse inhibition; startle; mollusc; Tritonia; sensorimotor gating; schizophrenia
Copyright © 1998 Society for Neuroscience 0270-6474/98/18208467-06$05.00/0
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