Activation reduction in anterior temporal cortices during repeated recognition of faces of personal acquaintances

Repeated recognition of the face of a familiar individual is known to show semantic repetition priming effect. In this study, normal subjects were rep eatedly presented faces of their colleagues, and the effect of repetition o n the regional cerebral blood flow change was measured using positron emiss ion tomography. They repeated a set of three tasks: the familiar-face detec tion (F) task, the facial direction discrimination (D) task, and the percep tual control (C) task. During five repetitions of the F task, familiar face s were presented six times from different views in a pseudorandom order. Ac tivation reduction through the repetition of the F tasks was observed in th e bilateral anterior (anterolateral to the polar region) temporal cortices which are suggested to be involved in the access to the long-term memory co ncerning people. The bilateral amygdala, the hypothalamus, and the medial f rontal cortices, were constantly activated during the F tasks, and consider ed to be associated with the behavioral. significance of the presented fami liar faces. Constant activation was also observed in the bilateral occipito temporal regions and fusiform gyri and the right medial temporal regions du ring perception of the faces, and in the left medial temporal regions durin g the facial familiarity detection task, which are consistent with the resu lts of previous functional brain imaging studies. The results have provided further information about the functional segregation of the anterior tempo ral regions in face recognition and long-term memory. (C) 2001 Academic Pre ss.