Normal subjects were used to investigate potential experimental utility of positron emission tomography (PET) neuroimaging during performance of the Shakow reaction time (RT) paradigm preliminary to application in schizophrenia research. It was hypothesized that different conditions of the Shakow crossover RT task, consisting of regular and irregular series of preparatory intervals (PI), would result in differential activation of contributory cerebral systems as indicated by regional cerebral blood flow (rCBF). Task-activated regional rCBF data were obtained from eleven normal volunteers by intravenous infusion of \sp{15}O radiolabeled water and PET. During PET scans, subjects performed one of three task conditions: a baseline motor task, RT with regular PIs, or RT with irregular PIs. Differences found between RT conditions in frontal, anterior cingulate, and parietal rCBF are congruent with currently prominent neurocognitive theories of executive function and support the potential utility of this paradigm in schizophrenia research
