rats ~7,000 (~14,000 on both sides): rhesus monkey and human 200,000 (400,000 on both sides) dopamine neurons
||Schultz W. Multiple dopamine functions at different time courses. Annu Rev Neurosci. 2007 30: 259-88. p.277 right column 2nd paragraphPubMed ID17600522
||Stark AK, Pakkenberg B. Histological changes of the dopaminergic nigrostriatal system in aging. Cell Tissue Res. 2004 Oct318(1):81-92. DOI: 10.1007/s00441-004-0972-9PubMed ID15365813
||P.277 right column 2nd paragraph: "There are only ∼7000 dopamine neurons in rats and 200,000 in rhesus monkeys and humans on each side of the brain (primary source), and their axons project to ∼1000 times more postsynaptic neurons in the striatum, cortex, amygdala, and other structures. We have learned from the neuropsychology of cortical lesions that the deficits reveal the negative image of the active, information-processing function of the area under study. However, this reasoning may not be applicable to dopamine functions. Despite being necessary for many behavioral processes, the limited numbers of dopamine neurons may not be numerous enough to encode actively in full detail the information necessary for controlling every single component of the large range of functions that become deficient following dopamine depletions. For most functions other than reward, the dopamine cell bodies may simply provide the synthesis and release machinery for a steady-state concentration of dopamine that is finely regulated by local mechanisms in the terminal areas and that plays a permissive role without encoding information in time."