Final answer:
The thalamus consists mainly of white matter, which serves as a relay for information between different parts of the brain.
Step-by-step explanation:
The thalamus consists mainly of white matter. It is a collection of several nuclei that serve as relays for information between different parts of the brain. The thalamus contains white matter running through it, which defines the three major regions of the thalamus. The white matter relays information from the limbic system, basal ganglia, and sensory cortex of the cerebrum to the cerebral cortex.