What is the Thalamus?

Michael Anissimov
Michael Anissimov

The thalamus, coined from the Greek word for "chamber", thálamos, is the part of the brain responsible for signal relaying and prioritization. It consists of twin bulb-shaped regions, the thalami, symmetrical about the brain's midline. They are so close to the center of the brain that they occasionally interconnect, but typically don't. The thalamus is part of the limbic system, the region of the brain largely associated with the emotions.

Signal relays and prioritization is done by the thalamus.
Signal relays and prioritization is done by the thalamus.

The thalamus is best known as the final relay station for perceptual data before it is passed on to the cerebral cortex. It receives input from diverse brain areas, primarily including all the senses except olfaction. It is also responsible for regulating motor control.

The thalamus is part of the limbic system, the region of the brain largely associated with the emotions.
The thalamus is part of the limbic system, the region of the brain largely associated with the emotions.

The sensory apparatus of the human body registers a tremendous amount of information, far more information than can be put to good use. The thalamus joins a series of other machinery whose purpose is to distill sensory information into a more interpretable and manageable form for higher brain sections. The thalamus is engaged in an intimate relationship with the cerebral cortex, with numerous mutual connections. These connections make up the thalamacortical loop.

Because the thalamus is the nucleus of so much relaying activity, it has long been regarded as the Rosetta stone of the nervous system, giving a lot of insight into the importance and direction of various neural signals. The thalamus also modulates arousal mechanisms, maintains alertness, and directs attention to sensory events.

The thalamus consists of three circuits: the specific nucleii, the reticular formation, and the intralaminar circuit. The specific nucleii are responsible for scanning the cerebral cortex and determining active brain regions, those firing at around 40Hz, then relaying this information to the rest of the thalamus. The reticular formation is constantly making intelligent guesses as to what sensory object is generating these activation patterns. The intralaminar circuit compares these pattern guesses with similar patterns in memory. All these circuits cooperate to produce a coherent framework for the interpretation of incoming sensory data.

Michael Anissimov
Michael Anissimov

Michael is a longtime wiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

You might also Like

Readers Also Love

Discussion Comments


Is it not possible that sleeplessness is a symptom of but not the cause of death in fatal familial Insomnia? If there is loss of neurons in the thalamus it stands to reason that the brain is receiving less and less sensory information and therefore sleep is not needed. However this lack of sensory input would cause a reduction in the regulatory role of the brain and the body would die from lack of maintenance.

The role of adenosine is cytoprotection and is produced by all cells, could it be that the levels rise as a result of the brain ignoring sensory input?


@ Parmnparsley- The Thalamus is the sensory switchboard of the brain, and the hypothalamus lies just below it. The thalamus relays signals to various parts of the brain that control behavior.

The hypothalamus receives signals that control sex drive, anxiousness, sleep and appetite, automatic nervous responses, and the pituitary gland. Essentially the hypothalamus is the emotion center, and the thalamus routes signals dealing with emotion to the hypothalamus.


@ Fiorite- I never thought about PTSD being brain damage...actually, I never really thought about what PTSD was until reading this article and your post. Honestly, I never knew much about the brain before this article. I have heard of things like the cerebral cortex, temporal lobes, pituitary glands, and hypothalamus, but not the thalamus. What is the difference between the thalamus and the hypothalamus?


Since the thalamus is the sensory gateway of the brain, thalamus function is what is affected in patients suffering from post-traumatic stress disorder (PTSD).

Research has shown that sever psychological trauma can disrupt the relay of information to other parts of the brain. Specifically, PTSD sufferers cannot process their traumatic memories in the correct fashion, ultimately having a negative effect on cognition and behavior. PTSD prevents a person from understanding the totality of a situation, and when the sufferer accesses a traumatic memory, the brain malfunctions and there is a temporary disconnect between certain parts of the brain.

The brain is a fascinating organ. It is fascinating that an organ can control every other organ in the body. The functions of the different parts of the brain are so complex that it is no wonder outside stimulants can have such a profound effect on one’s life.

Post your comments
Forgot password?