Pruning or tuning? Maturational profiles of face specialization during typical development.
Face processing undergoes significant developmental change with age. Two kinds of developmental changes in face specialization were examined in this study: specialized maturation, or the continued tuning of a region to faces but little change in the tuning to other categories; and competitive interactions, or the continued tuning to faces accompanied by decreased tuning to nonfaces (i.e., pruning).



Using fMRI, in regions where adults showed a face preference, a face- and object-specialization index were computed for younger children (5-8 years), older children (9-12 years) and adults (18-45 years). The specialization index was scaled to each subject's maximum activation magnitude in each region to control for overall age differences in the activation level.



Although no regions showed significant face specialization in the younger age group, regions strongly associated with social cognition (e.g., right posterior superior temporal sulcus, right inferior orbital cortex) showed specialized maturation, in which tuning to faces increased with age but there was no pruning of nonface responses. Conversely, regions that are associated with more basic perceptual processing or motor mirroring (right middle temporal cortex, right inferior occipital cortex, right inferior frontal opercular cortex) showed competitive interactions in which tuning to faces was accompanied by pruning of object responses with age.



The overall findings suggest that cortical maturation for face processing is regional-specific and involves both increased tuning to faces and diminished response to nonfaces. Regions that show competitive interactions likely support a more generalized function that is co-opted for face processing with development, whereas regions that show specialized maturation increase their tuning to faces, potentially in an activity-dependent, experience-driven manner.
Department of Psychology Shihezi University Xinjiang China; Department of Neurosciences Medical University of South Carolina Charleston South Carolina 29425.
Xun
X
Zhu
Department of Psychology College of Arts and Sciences University of Kentucky Lexington Kentucky 40506.
Ramesh S
RS
Bhatt
Department of Neurosciences Medical University of South Carolina Charleston South Carolina 29425.
Jane E
JE
Joseph
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000502:physiology*; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D000066499:Facial Recognition / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012938:Social Perception; D055815:Young Adult
Development; fMRI; face perception