Relationship of prepulse inhibition of the startle reflex to attentional and executive mechanisms in man.

Prepulse inhibition (PPI) of the startle reflex at short lead intervals is thought to reflect the operation of a preattentive "sensorimotor gating" mechanism, which suggests that processing of the prepulse stimulus should not be modulated prior to its inhibitory effects on startle. To test this hypothesis, we examined whether PPI is affected following habituation to the prepulse. PPI was measured in two sessions associated with either the presence (habituation condition) or the absence (control condition) of prepulse repetition. There was a trend for prepulse repetition to reduce the effectiveness of that prepulse in inhibiting the startle response. We also explored the relationship of PPI to scores in tests of selective and sustained attention and planning ability. Overall PPI performance was correlated to performance indices of planning ability and there was a trend level correlation with scores in selective but not sustained attention tests. These preliminary results merit further investigation.