Final answer:
White matter volume in the corpus callosum increases from around 5 to 20 years of age as a result of myelination, enhancing communication between the brain's hemispheres.
Step-by-step explanation:
The white matter in the corpus callosum increases in volume from childhood into late adolescence, specifically from around 5 to 20 years of age. This development corresponds to the process of myelination, where the axons of neural cells are coated with a fatty substance called myelin, which helps to increase the speed at which electrical impulses are passed along the nerves.
The corpus callosum is a thick bundle of fibers that connects the left and right hemispheres of the cerebrum, facilitating communication between them. This increase in white matter and the corresponding decrease in gray matter as seen in MRI images, signifies that the brain is undergoing significant development during these years. The implications of these developments in brain structure are also related to the behavior and cognitive abilities of teenagers.