nucleus basalis of Meynert

Structure

• a group of large cholinergic neurons 30-50 um in diameter within the substantia innominata
• the nucleus basalis is larger in humans than in other species & is a major component of the substantia innominata.

• on coronal section the nucleus basalis appears superior to the hippocampal formation & interpeduncular fossa, inferior to the putamen & anterior commissure, lateral to the optic tract & nucleus accumbens, & medial to the claustrum.

Afferents

the nucleus basalis receives afferents from:

• hypothalamus
• amygdala
• peripeduncular nucleus
• midbrain

Efferents

• cholinergic neurons in the nucleus basalis project to all layers of the cerebral cortex, with highest density in layers 1 & 2 & upper regions of layer 3.
• axons of individual magnocellular neurons of the nucleus basalis appear to have limited collateralization, with their terminals mainly confined to a single cytoarchitectonic area.
• the nucleus basalis also contains non cholinergic neurons, some containing GABA may of which project to the olfactory bulb & hippocampus

Pathology

• cortical lesions cause atrophy of ipsilateral magnocellular neurons in the nucleus basalis
• shrinkage &/or loss of these neurons is a frequent & early feature of Alzheimer's disease. (see anatomic predilection of Alzheimer's pathology)
• other disorders affecting the nucleus basalis include
  • Parkinson's disease & diffuse Lewy body disease

* see diseases affecting the CNS cholinergic system

More general terms

• septal nucleus

Additional terms

• CNS cholinergic system
• diseases affecting the CNS cholinergic system
• septum pellucidum
• substantia innominata

Component of

• substantia innominata