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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 [4]. 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 Afferents: the nucleus basalis receives afferents from: 1) hypothalamus 2) amygdala 3) peripeduncular nucleus 4) midbrain 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

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

General

septal nucleus

References

  1. The Human Nervous System, George Paxinos, Academic Press, San Diego CA 1990
  2. Role of cholinergic therapy in treatment of Alzheimer's disease & other dementias, Farlow, M et al, 2001
  3. Principals of Neuroscience, 3rd ed, Kandel et al (eds), Elsevier, NY, 1991, pg 980-81
  4. http://www9.biostr.washington.edu/cgi-bin/DA/imageform

Component-of

substantia innominata

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