Microstructural correlates of infant functional development: example of the visual pathways.
The development of cognitive functions during childhood relies on several neuroanatomical maturation processes. Among these processes is myelination of the white matter pathways, which speeds up electrical conduction. Quantitative indices of such structural processes can be obtained in vivo with diffusion tensor imaging (DTI), but their physiological significance remains uncertain. Here, we investigated the microstructural correlates of early functional development by combining DTI and visual event-related potentials (VEPs) in 15 one- to 4-month-old healthy infants. Interindividual variations of the apparent conduction speed, computed from the latency of the first positive VEP wave (P1), were significantly correlated with the infants' age and DTI indices measured in the optic radiations. This demonstrates that fractional anisotropy and transverse diffusivity are structural markers of functionally efficient myelination. Moreover, these indices computed along the optic radiations showed an early wave of maturation in the anterior region, with the posterior region catching up later in development, which suggests two asynchronous fronts of myelination in both the geniculocortical and corticogeniculate fibers. Thus, in addition to microstructural information, DTI provides noninvasive exquisite information on the functional development of the brain in human infants.
Dubois
Jessica
J
Unité de Neuroimagerie Anatomique et Fonctionnelle, Commissariat à l'Energie Atomique/Saclay/Division des Sciences du Vivant/Institut d'imagerie Biomédicale/Service Hospitalier Frédéric Joliot, 91401 Orsay, France. jessica.dubois@centraliens.net
Dehaene-Lambertz
Ghislaine
G
Soarès
Catherine
C
Cointepas
Yann
Y
Le Bihan
Denis
D
Hertz-Pannier
Lucie
L
D001931:Brain Mapping / Q000379:methods; D002657:Child Development / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009431:Neural Conduction / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D014795:Visual Pathways / Q000254:growth & development*