GLOSSARY

The thalamus consists of two egg-shaped masses of grey matter at the centre of the brain (in the diencephalon) that act as the main relay station and gateway for information; almost all sensory information (except smell) passes through it before reaching the cerebral cortex.

Functions

• Sensory relay: the lateral geniculate nucleus (vision), the medial geniculate nucleus (hearing), and the VPL and VPM nuclei (body sensation).
• Motor relay: passes information from the cerebellum and basal ganglia to the motor cortex.
• Gating and filtering: selects important information and dampens unimportant input, especially in attention and sleep.
• Arousal and the sleep–wake cycle: together with the reticular activating system.
• Memory and emotion: the anterior and medial nuclei.

Key Point