Neurogenesis and rTMS. (A) Dopaminergic neurons reside in the substantia nigra pars compacta (SNc), which is located in the ventral midbrain, and send axonal projections to the striatum, which is situated in the forebrain. Neural stem cells are located in the adult SVZ, immediately adjacent to the striatum, with is rich in dopaminergic afferents from the SNc. In the 6-OHDA animal model of Parkinson's disease, the nigral dopaminergic neurons are destroyed unilaterally by means of a stereotactic injection of the toxin, as indicated by the needle. The consecutive depletion of dopamine (DA↓) in the striatum leads to a decreased proliferation of progenitor cells in the SVZ. (B) In rats with unilateral 6-OHDA lesion of the SNc, rTMS induces an in situ differentiation of SVZ-derived precursors in dopamine-producing neurons. Some nucleus marked with BrdU (green) colocalize with the cytoplasmatic TH (red). OB: olfactory bulb; V: ventricle; VZ: ventricular zone.