Atlas of cholinergic neurons in the forebrain and upper brainstem of the macaque based on monoclonal choline acetyltransferase immunohistochemistry and acetylcholinesterase histochemistry

Choline acetyltransferase immunohistochemistry was used to map the cholinergic cell bodies in the forebrain and upper brainstem of the macaque brain. Neurons with choline acetyltransferase-like immunoreactivity were seen in the striatal complex, in the septal area, in the diagonal band region, in the substantia innominata, in the medial habenula, in the pontomecencephalic tegmentum and in the occulomotor and trochlear nuclei. The ventral striatum contained a higher density of cholinergic cell bodies than the dorsal striatum. All of the structures that contained the choline acetyltransferase positive neurons also had acetylcholinesterase-rich neurons. Choline acetyltransferase positive neurons were not encountered in the cortex. Some perikarya in the midline, intralaminar, reticular and limbic thalamic nuclei as well as in the hypothalamus were rich in acetylcholinesterase but did not give a positive choline acetyltransferase reaction. A similar dissociation was observed in the substantia nigra, the raphe nuclei and the nucleus locus coeruleus where acetylcholinesterase-rich neurons appeared to lack perikaryal choline acetyltransferase activity.