Glossary
Thalamus
What is the thalamus?
The thalamus is a paired structure deep within the brain, in the diencephalon. It processes and relays information through connections with the cerebral cortex and other brain regions. It also contributes to attention, memory, arousal, and sleep-wake regulation.
Structure and function
Thalamic nuclei
The thalamus contains groups of neurons called nuclei. One traditional scheme divides them into relay, association, and nonspecific nuclei. Other schemes distinguish first-order and higher-order relays by the inputs that drive them. These are different ways to describe the organization.
Sensory and motor processing
The lateral geniculate nucleus processes visual information, the medial geniculate nucleus processes auditory information, and ventral posterior nuclei process somatosensory information. Ventral anterior and ventral lateral nuclei participate in motor circuits.
Consciousness and arousal
Connections with cortical and brainstem systems help regulate arousal. The thalamic reticular nucleus forms a shell around much of the thalamus and sends inhibitory signals to other thalamic nuclei, helping regulate their activity.
Attention, learning, and memory
Thalamic interactions with frontal and parietal regions contribute to attention. The anterior thalamic nuclei participate in extended memory circuits involving the hippocampus and diencephalon, including circuits important for spatial and episodic memory.
Why it matters
The thalamus is more than a passive switchboard. Its circuits help shape the information available to the cortex and how cortical regions interact.