General to specific development of functional activation in the cerebral cortexes of 2- to 3-month-old infants.
A critical issue in the functional development of the cerebral cortex is whether cortical regions are functionally differentiated in early infancy. Although a growing number of neuroimaging studies have revealed that functional differentiation between early sensory and association regions of the cortex is already present at 3 months of age, it is unclear how functional regions per se emerge in the earlier developmental period. Here, we present 3 possible hypotheses regarding the functional development of the cerebral cortex as follows: (1) functionally differentiated regions are prespecified in the early developmental period; (2) functional activations appear in a hierarchical order from early sensory regions to the association regions; and (3) functional activation patterns change in a general-to-specific manner, thereby increasing the localization of regions activated by a particular stimulus and increasing the exclusivity of the response to specific stimuli within a particular cortical region. In the present study, we used multichannel near-infrared spectroscopy (NIRS) to measure cortical hemodynamic responses to 2 different video images of colorful mobile objects and black-and-white checkerboard pattern reversals over the occipital and prefrontal regions in awake 2-month-old infants. Both visual stimuli produced comparative activations over broad regions of the cortex including the early sensory and association regions, supporting the general-to-specific development (Hypothesis 3). This result suggests that functional cortical regions emerge between 2 and 3 months of age for visual perception.
Watanabe
Hama
H
Department of Physical and Health Education, Graduate School of Education, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. hama@p.u-tokyo.ac.jp
Homae
Fumitaka
F
Taga
Gentaro
G
D002540:Cerebral Cortex / Q000098:blood supply / Q000254:growth & development* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D002657:Child Development / Q000502:physiology*; D003116:Color; D005260:Female; D006801:Humans; D007223:Infant; D016014:Linear Models; D008297:Male; D008959:Models, Neurological; D009778:Occipital Lobe / Q000098:blood supply / Q000254:growth & development / Q000502:physiology; D010775:Photic Stimulation; D017397:Prefrontal Cortex / Q000098:blood supply / Q000254:growth & development / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared; D014741:Video Recording; D014796:Visual Perception / Q000502:physiology*