title: Dedifferentiated face processing in older adults is linked to lower resting state metabolic activity in fusiform face area.
abstract: We used multimodal brain imaging to examine possible mediators of age-related neural dedifferentiation (less specific neural activation) to different categories of stimuli that had been shown in previous research. Specifically, we examined resting blood flow and brain activation in areas involved in object, place and face perception. We observed lower activation, specificity, and resting blood flow for older adults (OA) than younger adults (YA) in the fusiform face area (FFA) but not in the other regions of interest. Mediation analyses further revealed that FFA resting state blood flow mediated age differences in FFA specificity, whereas age differences in visual and cognitive function and cortical thickness did not. Whole brain analyses also revealed more activated voxels for all categories in OA, as well as more frontal activation for faces but not for the other categories in OA than YA. Less FFA specificity coupled with more frontal activation when passively viewing faces suggest that OA have more difficulty recruiting specialized face processing mechanisms, and the lower FFA metabolic activity even when faces are not being processed suggests an OA deficiency in the neural substrate underlying face processing. Our data point to a detuning of face-selective mechanisms in older adults.
authors.affiliation: Department of Psychology, Brandeis University, Waltham, MA 02453, USA.
authors.forename: Leslie
authors.initials: L
authors.lastname: Zebrowitz
authors.affiliation: MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Harvard University, Boston, MA 02129 USA.
authors.forename: Noreen
authors.initials: N
authors.lastname: Ward
authors.affiliation: Department of Psychology, Brandeis University, Waltham, MA 02453, USA.
authors.forename: Jasmine
authors.initials: J
authors.lastname: Boshyan
authors.affiliation: Department of Psychology, Brandeis University, Waltham, MA 02453, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Gutchess
authors.affiliation: MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Harvard University, Boston, MA 02129 USA; Gillberg Neuropsychiatry Center, Gothenburg University, Sweden. Electronic address: nouchine@nmr.mgh.harvard.edu.
authors.forename: Nouchine
authors.initials: N
authors.lastname: Hadjikhani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000378:metabolism; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D000066499:Facial Recognition / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000378:metabolism*; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: Aging; Cerebral blood flow; Dedifferentiation; FMRI; Face processing; Fusiform face area