Relatively little attention has been paid to the exact involvement of DAergic structures in the midbrain in diseases of the aging brain, especially dementia (see Sect. 5 for review). Cell loss in the SN and VTA is one of the main features in PD, whereas degenerative changes characteristic for AD have been suggested in the VTA and adjacent part of the SNc, i.e., those parts of the DAergic mesencephalic cell continuum with cortical projections (see Sects 4.4, 4.5, and 5.3). However, apart from Bogert’s study (Bogerts et al. 1983), neuronal densities in only a few sections were measured, which have to be considered carefully (see Coleman and Flood 1987 for discussion) and which at best give only a rough estimation of the actual cell loss in a given structure.
KeywordsCell Loss Spherical Diameter DAergic Neuron Ventral Cochlear Nucleus Pigment Neuron
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