Thalamus

Function

The thalamus is the brain's mandatory relay: an egg-shaped nucleus pair through which every sensation but smell passes en route to consciousness, and through which the cortex communicates with itself and with the cerebellum and basal ganglia.

More than a passive relay, its nuclei gate, prioritise and modulate — the reticular nucleus wraps it like a firewall, tuning what deserves awareness. It is also the anchor of the sleep-wake cycle: arousal systems from the brainstem drive thalamocortical resonance whose rhythmic signatures define the EEG's sleep stages.

Blood supply

Thalamoperforating and thalamogeniculate arteries of the posterior cerebral circulation.

Nerve supply

Extensive reciprocal cortical connections.

Clinical relevance

Thalamic pain syndrome (Dejerine–Roussy)

Small vessel infarcts leave burning, treatment-resistant pain on the opposite body — central pain at its most stubborn.

Thalamic aphasia

Left thalamic lesions mute spontaneous speech while repetition survives.

Related conditions

• Parkinson's disease