A technique is described which has been used to quantitate the 3-dimensional configuration of the midbrain dopamine (DA) nuclei (cell groups A8, A9, and A10). This technique provides cell counting information, for example, the BALB/c mouse has approximately 25,000 midbrain DA neurons, the albino rat has about 40,000 neurons, and man (33 year old) has approximately 450,000 neurons. Furthermore, cell density topography maps were constructed which enable quantitation of the 3-dimensional cellular distribution. These topography maps revealed both similarities and differences across the three species examined. The number of midbrain DA neurons is known to be genetically determined and to decrease with aging. DA cell number is also related to motoric behavior and neurologic and perhaps psychiatric disease. The ability to quantitate DA regional cell densities represents a new technique which can be used to study the neurobiology of DA neurons and relate DA cell number to both normal and abnormal behaviors.
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