Cortex, cholinergic innervation

Mesulam, M.M. (1996) The systems-level organization of cholinergic innervation in the human cerebral cortex and its alterations in Alzheimer s disease. Prog Brain Res 109 285-297. 

Mesulam MM. 2004. The cholinergic innervation of the human cerebral cortex. Prog Brain Res 145 67-78. 

Biochemical measurement of distinct levels of acetylcholine (McIntosh, 1941 Kasa et al., 1982) and its biosynthetic enzyme, choline acetyltransferase (ChAT) in cerebellar tissue (Kasa and Silver, 1969 Salvaterra and Foders, 1979 Hayashi, 1987 and others) indicated the presence of a cholinergic innervation in the cerebellum. ChAT activity varies among different lobules with the highest levels in the nodulus and ventral uvula. Following deafferentation of the cerebellar cortex, ChAT activity is considerably de-... 

Actions of acetylcholine (ACh) are referred to as muscarinic based on the observation that muscarine acts selectively at certain sites and, quahtatively, produces the same effects as ACh. Peripheral muscarinic acetylcholine receptors are found primarily on autonomic effector cells innervated by postganghonic parasympathetic nerves and on some cells that receive little or no cholinergic innervation but express muscarinic receptors e.g., vascular endothelial cells). There are also muscarinic receptors in ganglia and the adrenal meduUa, where muscarinic stimulation seems to modulate the effects of nicotinic stimulation. Within the central nervous system (CNS), the hippocampus, cortex, and thalamus have high densities of muscarinic receptors. 

The human cortex receives dense cholinergic innervation from cells in the nucleus basalis of Mcynert (Ch4 Selden et al, 1998). Anaiogou.s to rodent brain, two bundle.s of fibers (medial and lateral tracts) originate in the nucleus ba.sali.s and innervate the cerebral cortex and amygdala. AChE, ChAT, and NGF receptors arc exprc.ssed by these neurons. 

Jones, B. E. (2004). Activity, modulation and role of basal forebrain cholinergic neurons innervating the cerebral cortex. Prog. Brain Res. 145, 157-69. 

The cholinergic pathways in the mammalian brain are extremely diffuse and arise from cell bodies located in the hindbrain and the midbrain. Of these areas, there has been considerable interest of late in the nucleus basalis magnocellularis of Meynert because this region appears to be particularly affected in some patients with familial Alzheimer s disease. As the projections from this area innervate the cortex, it has been speculated... 

Figure 2.15. Distribution of muscarinic and nicotinic receptors in the human brain. Note the very restricted distribution of the nicotinic receptors. Cholinergic tracts arising from the magnocellular cholinergic nuclei innervate large areas of the cortex...

Cortical afferents to the cholinergic basal forebrain would provide the specific information required, but the extent to which the cortex innervates the... 

Cortical and hippocampal pyramidal cells are noteworthy in at least three ways (1) they are preferentially, but not exclusively, innervated by cholinergic terminals (2) they are implicated as a potential site of consciousness and (3) they are enriched with cytoskeletal proteins, some of which undergo hyperphosphorylation in Alzheimer s disease. A novel signal transduction mode may exist within the large pyramidal cells of the cerebral cortex and hippocampus. 

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