What Is the Thalamus?

Deep Brain Structure Serves as Relay Station for Senses Between Body and Mind


What is the thalamus? Learn about this important deep brain structure and how it serves as a relay point for the body's senses and mind as well as playing a critical function in sleep.

Deep within the brain's hemispheres near the midline are two masses of gray matter that lie on either side of a fluid space called the third ventricle. Anatomically, these structures seem to sit at the top of the brainstem.

These areas, each individually called the thalamus and collectively known as thalami, serve as an important relay station for senses between the body and mind. Sensory information, including pain perception, is delivered to the surface of the brain via the thalami. This surface, called the cerebral cortex, contains many of the neurons important for conscious perception, awareness, and numerous brain functions.

In addition, each thalamus plays an important role in coordinating the surface of the brain during sleep. The thalami generate characteristic EEG findings of stage 2 sleep called sleep spindles and K-complexes. In a way, the thalami are responsible for getting the entire brain into a similar electrical state of consciousness. This may reduce the likelihood of having mixed states, characteristic of the sleep behaviors called parasomnias.


Kryger, MH et al. "Principles and Practice of Sleep Medicine." ExpertConsult, 5th edition, 2011.

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