title: Neural representation of face familiarity in an awake chimpanzee.
abstract: Evaluating the familiarity of faces is critical for social animals as it is the basis of individual recognition. In the present study, we examined how face familiarity is reflected in neural activities in our closest living relative, the chimpanzee. Skin-surface event-related brain potentials (ERPs) were measured while a fully awake chimpanzee observed photographs of familiar and unfamiliar chimpanzee faces (Experiment 1) and human faces (Experiment 2). The ERPs evoked by chimpanzee faces differentiated unfamiliar individuals from familiar ones around midline areas centered on vertex sites at approximately 200 ms after the stimulus onset. In addition, the ERP response to the image of the subject's own face did not significantly diverge from those evoked by familiar chimpanzees, suggesting that the subject's brain at a minimum remembered the image of her own face. The ERPs evoked by human faces were not influenced by the familiarity of target individuals. These results indicate that chimpanzee neural representations are more sensitive to the familiarity of conspecific than allospecific faces.
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo , Japan ; Faculty of Sociology, Kansai University , Japan.
authors.forename: Hirokata
authors.initials: H
authors.lastname: Fukushima
authors.affiliation: Great Ape Research Institute of Hayashibara Biochemical Laboratories, Inc. , Japan ; Wildlife Research Center, Kyoto University , Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hirata
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo , Japan ; JST, CREST , Japan.
authors.forename: Goh
authors.initials: G
authors.lastname: Matsuda
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo , Japan ; Department of Human Relations Studies, School of Human Cultures, The University of Shiga Prefecture , Japan.
authors.forename: Ari
authors.initials: A
authors.lastname: Ueno
authors.affiliation: Great Ape Research Institute of Hayashibara Biochemical Laboratories, Inc. , Japan ; EarthMate-ChimpanzeeNEXT , Japan.
authors.forename: Kohki
authors.initials: K
authors.lastname: Fuwa
authors.affiliation: Great Ape Research Institute of Hayashibara Biochemical Laboratories, Inc. , Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Sugama
authors.affiliation: Great Ape Research Institute of Hayashibara Biochemical Laboratories, Inc. , Japan ; EarthMate-ChimpanzeeNEXT , Japan.
authors.forename: Kiyo
authors.initials: K
authors.lastname: Kusunoki
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo , Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hiraki
authors.affiliation: Section of Language and Intelligence, Primate Research Institute, Kyoto University , Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tomonaga
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo , Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Hasegawa
keywords: Chimpanzee; Comparative neuroscience; Event-related potentials; Face recognition; Familiarity; Memory; Self recognition; Social cognition; Species effect