title: Separation of phasic arousal and expectancy effects in a speeded reaction time task via fMRI.
abstract: Sixteen neurologically normal volunteers performed a 2-choice speeded reaction time (RT) task in which the imperative was the change in color of a clock hand. During trial blocks with low temporal uncertainty (good clock condition), this imperative stimulus occurred at a fixed location (e.g., 2:00). In the bad clock condition, the clock was unpredictive of imperative onset. On half of both good and bad clock trials, a task-irrelevant, cutaneous accessory stimulus accompanied the imperative. The speeding of reactions by the accessory was associated with activation primarily in and near the supramarginal gyrus of the parietal lobe. Contrasts of good- versus bad-clock conditions revealed activation in a variety of perceptual, motor, and executive control regions. Apart from interactions within the cerebellum and left anterior insula, there was little overlap between structures influenced by the arousal and expectancy manipulations.
authors.affiliation: Department of Psychological Sciences, University of Missouri-Columbia, Columbia, Missouri 65211, USA. HackleyS@Missouri.edu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Hackley
authors.forename: Robert
authors.initials: R
authors.lastname: Langner
authors.forename: Bettina
authors.initials: B
authors.lastname: Rolke
authors.forename: Michael
authors.initials: M
authors.lastname: Erb
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Grodd
authors.forename: Rolf
authors.initials: R
authors.lastname: Ulrich
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology*; D001288:Attention / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D012718:Set, Psychology