Which structure in the brain is known for containing a large amount of white matter?

The corpus callosum is the structure in the brain known for containing a large amount of white matter. It serves as a critical communication pathway between the left and right hemispheres of the brain, facilitating the transfer of information between them. The white matter is composed primarily of myelinated axons, which are crucial for efficient signal transmission, contributing to various cognitive and motor functions.

In contrast, other structures mentioned have different compositions and roles. The cerebellum, while also important for coordination and balance, has both gray and white matter but is not specifically recognized for its white matter content in the same sense as the corpus callosum. The pineal gland is primarily an endocrine structure that produces melatonin and does not contain significant white matter. The thalamus plays a role in relaying sensory and motor signals to the cerebral cortex but also does not have the same extensive white matter structure as the corpus callosum.