We previously reported a patient who exhibited a peculiar form of delusional misidentification. She had a selective deficit in retrieving family relationships between herself and her daughters and husband (i.e., she misidentified her daughters as her sisters and her husband as her father) despite being able to retrieve their names and faces and some person-specific semantic information (e.g., occupation). Based on this finding, the present positron emission tomography study was designed to elucidate the brain mechanisms underlying the retrieval of family relationships in healthy individuals. We found that the right inferior temporal gyrus, in which hypoperfusion was detected in the patient we had reported, was significantly activated during the retrieval of family relationships compared with names and occupations. These findings indicate that the retrieval of the relationships between oneself and one's family members may require a specific cognitive process dissociated from the retrieval of names and other person-specific semantic information.
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