Final answer:
In middle childhood, white matter density steadily decreases.
Step-by-step explanation:
In middle childhood, white matter density steadily decreases.
White matter refers to the parts of the brain made up of myelinated nerve fibers. These fibers connect different regions of the brain, allowing for communication and information processing.
As children grow and mature during middle childhood, their brains undergo changes in structure and function. One of these changes is a reduction in white matter density, which is believed to reflect the pruning of unnecessary or unused neural connections.