The thalamus is concerned with the motor control that people have over their bodies. It also helps to regulate a person's sleep and wake cycles. It receives signals related to vision, hearing, taste and other bodily sensations, and it sends these signals on the cerebral cortex. However, the thalamus doesn't process the sense of smell. In many ways, the thalamus serves as a relay center for the brain.
The thalamus is part of the diencephalon of the forebrain along with the subthalamus and the hypothalamus. It's a walnut-size structure found at the top of the brainstem between the midbrain and the cerebral cortex. It has two halves that are a little over 2 inches in length. The thalamus encircles the brain's third ventricle, which is one of the fluid-filled spaces that are normally found in the brain.
The nerve fibers in the thalmus reach out toward the cortex, and the structure of the thalmus itself has nerve fibers that separate it into different regions. These regions make up the allothalamus and the isothalamus. The thalamus is part of the limbic system, which is an ancient part of the brain. Not surprisingly, it looks very similar to the brain of a marine iguana.