Thalamic Relay Neuron

Neuron thalamicum

The gatekeeper neuron of cortex, almost every sensory modality, every cerebellar output, and every basal-ganglia signal passes through a thalamic relay on its way to cerebral cortex.

Function

Relay neurons switch between tonic firing (during alert wakefulness, faithfully transmitting input to cortex) and bursting (during sleep and drowsiness, generated by de-inactivation of T-type Ca2+ channels). This switch gates sensory information access to cortex across the sleep-wake cycle.

Morphology

A compact soma with a tight, bushy radial dendritic tree and a single ascending axon that projects to a topographically-specific patch of cortex.

Specification

  • Neurotransmitter: Glutamate
  • Receptors: GABA-A; GABA-B; Metabotropic glutamate
  • Location: Thalamus, specific relay nuclei for each modality (LGN for vision, MGN for hearing, VPL/VPM for somatosensation, VA/VL for motor).
  • Projections: Cerebral cortex
  • Firing: Tonic (awake); Bursting (sleep)
  • Markers: SLC17A6/VGLUT2; TCF7L2; CALB1/calbindin or PVALB/parvalbumin (nucleus/population markers)
  • Developmental origin: Diencephalon
  • Disease: Epilepsy (Absence seizures)

References

  1. Sherman SM & Guillery RW (2002). The role of the thalamus in the flow of information to the cortex.. Philos Trans R Soc Lond B 357: 1695–1708 PMID 12626004

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