Event-related potentials correlate with task-dependent glucose metabolism

Cognitive processing is associated with brain electrical activity that is r eflected in event-related potentials (ERP), ERP during a target detection t ask, and regional cerebral glucose metabolism (CMRglc) measured simultaneou sly, may be influenced by the same neurophysiologic processes. We tested th e hypothesis that ERP factors could be directly correlated with CMRglc to d erive functional brain maps of brain activity at 120, 160, 200, 280, and 40 0 ms following stimulus presentation in a target detection task. We control led for the potential confounding effects of age, sex, and task accuracy, a nd correlate target-related and nontarget-related ERP separately, Increases and decreases in CMRglc at each time point were identified with statistica l parametric mapping (P < 0.001, uncorrected). The 120- and 160-ms maps wer e the same for target and nontarget processing, while maps for 280 and 400 ms clearly distinguished between targets and nontargets, Extrinsic (early) cognitive processes that depend mainly on stimulus characteristics show les s variation based on stimulus meaning (i.e., letter vs shape; target vs non target) than later (intrinsic) cognitive processes. These early effects are lateralized to the left hemisphere, for negative ERP factors, and positive ERP-PET correlations are more likely than negative ERP-PET correlations. T hus, brain areas related to task processing impact both ERP and CMRglc meas ures, suggesting a shared neurophysiologic mechanism for negative ERP facto rs and increased CMRglc. Direct statistical analysis of these two measures using statistical parametric mapping provides high spatial and temporal res olution in multisubject experiments, while requiring only a single (18)FDG PET scan per subject. (C) 2000 Academic Press.