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Vaidehi Natu, Michael Barnett, Jake Hartley, Jesse Gomez, Kalanit Grill-Spector; Neural discriminability for face identity improves from childhood to adulthood. Journal of Vision 2015;15(12):1190. doi: 10.1167/15.12.1190.
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Face recognition requires fine-grained discrimination among highly similar exemplars. Discrimination accuracy increases with increasing perceptual dissimilarities between identities and this accuracy improves from age five. Neurally, recovery from adaptation also increases with dissimilarities among identities. However, it is unknown whether neural mechanisms underlying face discrimination develop from age 5 to adulthood. We addressed this question using an fMRI-adaptation (fMRI-A) paradigm, in which subjects viewed own-age faces and other-age faces that parametrically varied in their degree of similarity. We examined if there are differences in neural adaptation profiles of face-selective regions in the inferior occipital gyrus (IOG-faces), posterior fusiform gyrus (pFus-faces/FFA-1), and mid fusiform gyrus (mFus-faces/FFA-2) across children (ages 5-12, n=15) and adults (ages 19-34, n=12). We generated face identity morphs, whereby each morph was a linear weighting of a source face and one of six target faces. Morph-levels ranged from source face (0%) to target faces (100%), by 20% increments. Each block consisted of 6 identities at the same morph-level from their source face. We measured neural adaptation with respect to age of subject and age of stimuli in face-selective regions. First, we find a linear relationship between the response amplitude across morph-levels, with larger slope in adults than in children, in the left IOG and right pFus and mFus. Second, adults as compared to children showed larger fMRI-A, defined as the difference in the response amplitude to 100% versus 0% faces, in the left IOG, bilateral pFus, and right mFus. Third, we found an own-age bias that is larger fMRI-A to own-age faces than other-age faces in bilateral pFus. Our results suggest that neural sensitivity to detect small changes in face identity improves with age, which may be linked to developments in perceptual discriminability throughout childhood.
Meeting abstract presented at VSS 2015
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