Prestimulus modification of the startle reflex: relationship to personality and physiological markers of dopamine function.

Prepulse inhibition (PPI), a measure of sensorimotor gating, is regulated by dopamine (DA) in rodents. We examined the relationship of PPI in humans to putative markers of brain DA function: (1) novelty seeking (NS; Cloninger's Tridimensional Personality Questionnaire (TPQ)), which is associated with specific DA receptor subtypes, and is reduced in Parkinson's Disease; (2) blink rate, which is increased in primates by DA agonists, and is reduced in Parkinson's Disease. PPI, TPQ and blink rate were measured in 79 normal adult males. A significant negative correlation was observed between resting blink rate and mean PPI, but not between NS and PPI. Blink rate correlated positively with resting EMG level, but this did not account for the relationship between blink rate and PPI. In normal male humans, PPI is inversely related to a physiological marker of resting DA tone (blink rate), but not to a putatively DA-linked personality trait (high NS).