Background: Inhibition of startle by weak prestimuli is called prepulse inhibition (PPI). It has recently been reported that 10- to 20-dB prepulses trigger eye-blink motor activity and PPI in normal human subjects. Motor activity after prepulses correlated negatively with PPI in four of nine possible conditions. We now report the relationship between prepulse-elicited startle (PPES) and PPI using weak prepulses.
Methods: We assessed PPI and PPES using 1- to 5-dB prepulses in humans and in rats after treatment with vehicle or apomorphine.
Results: Prepulses inhibited startle in an intensity-dependent fashion but elicited no startle activity in humans or rats. Apomorphine eliminated PPI in rats and produced a well-documented increase in stimulus-independent motor activity but did not stimulate PPES.
Conclusions: In humans and rats, PPES is not a necessary condition for either the elicitation or the disruption of PPI.
Copyright 2004 Society of Biological Psychiatry