VIII. 4. Neural Correlates of Deception

(fMRI) on deception have reported the involvement of the prefrontal cortex (PFC) 1-6) , which has an indispensable role for executive function. Activation of the anterior cingulate cortex (ACC), which has been regarded as a substantial area for conflict monitoring, has also often been reported 4-6) . Although these previous studies indicate crucial roles of the PFC and ACC in human deception, the specific role of each region during deception is still unclear. In the present PET study, we examined brain activity focusing on two types of deception for past episodes: deception for experienced events (pretending not to know) and deception for un-experienced events (pretending to know). During two deception conditions and two truth conditions, subjects were presented with old photographs related to experienced events in one and new photographs related to un-experienced events in the other. We expected the PFC to be active during the two deception conditions compared to the two truth conditions, because the former necessitate executive functions. In contrast, we anticipated that the ACC would be active only during the deception condition in which subjects were asked to tell lies in response to the old photographs (pretending not to know). The old photographs, compared with the new ones, would elicit stronger conflict for the inhibition of true answers during deception because the memory of experienced events would be vividly recovered by recognition of the old photographs, but not by the new photographs. Before PET scanning, subjects experienced 20 real-world events. During PET,