title: Variable foreperiod deficits in Parkinson's disease: dissociation across reflexive and voluntary behaviors.
abstract: The effect of a visual warning signal (1.0-6.5 s random foreperiod, FP) on the latency of voluntary (hand-grip) and reflexive (startle-eyeblink) reactions was investigated in Parkinson's disease (PD) patients and in young and aged control subjects. Equivalent FP effects on blink were observed across groups. By contrast, FP effects diverged for voluntary responses across groups with no effect of foreperiod duration for PD patients. The convergence of these results with findings from animal research suggests that interval-timing processes associated with higher level voluntary behaviors are dependent upon intact dopaminergic pathways, while those associated with lower level reflexive behaviors are spared in PD.
authors.affiliation: Duke University Center for the Study of Aging and Human Development, Brain Imaging and Analysis Center, Box 3918, Duke University Medical Center, Durham, NC 27710, USA. jurkowski@biac.duke.edu
authors.forename: Anita J
authors.initials: AJ
authors.lastname: Jurkowski
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Stepp
authors.forename: Steven A
authors.initials: SA
authors.lastname: Hackley
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D001143:Arousal / Q000502:physiology; D001245:Association Learning / Q000502:physiology*; D001767:Blinking / Q000502:physiology; D003463:Cues; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D010300:Parkinson Disease / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D013216:Reflex, Startle / Q000502:physiology; D013998:Time Perception / Q000502:physiology*