Cortical networks recruited for time perception: A monkey positron emission tomography (PET) study

The presence of an "internal clock" in the brain has been assumed to underl ie the information processing related to time. This clock plays a critical role in time keeping and time perception, which are closely associated with integrated functions in the brain. To identify the brain areas recruited f or time keeping and time perception, we performed positron emission tomogra phy (PET) studies with rhesus monkeys to measure regional cerebral blood ho w (rCBF) as an index of neural activity during time discrimination tasks of different durations ranging from 400 to 1500 ms. Changes in rCBF that cova ried significantly with the durations of the target being perceived by subj ects were found in the dorsolateral prefrontal cortex (DLPFC), the posterio r part of the inferior parietal cortex, basal ganglia, and posterior cingul ate cortex. Furthermore, a loss of neuronal function in the DLPFC caused by a local application of bicuculline resulted in the selective reduction of performance in time discrimination tasks. The results indicate that a neura l network composed of the posterior inferior parietal cortex to the DLPFC p lays a crucial role in the temporal monitoring process in time perception. (C) 2001 Academic Press.