A new dopaminergic nigro-olfactory projection.

Parkinson disease (PD) is a neurodegenerative disorder characterized by massive loss of midbrain dopaminergic neurons. Whereas onset of motor impairments reflects a rather advanced stage of the disorder, hyposmia often marks the beginning of the disease. Little is known about the role of the nigro-striatal system in olfaction under physiological conditions and the anatomical basis of hyposmia in PD.

Neurogenesis in substantia nigra of parkinsonian brains?

The clinical motor dysfunction in Parkinson's disease is primarily the consequence of a progressive degeneration of dopaminergic neurons in the substantia nigra of the nigrostriatal pathway. The degeneration of this tract provokes a depletion of dopamine in the striatum, where it is required as a permissive factor for normal motor function. Despite intense investigations, no effective therapy is available to prevent the onset or to halt the progression of the neuronal cell loss.