The substantia nigra is strongly associated with dopamine-producing neurons involved in movement.
This dark-colored structure lies in the midbrain and has two main parts: the pars compacta and pars reticulata. Dopaminergic neurons in the pars compacta project to the striatum through the nigrostriatal pathway, helping regulate basal-ganglia circuits involved in selecting and scaling movement.
Loss of these neurons is a central feature of Parkinson’s disease and contributes to symptoms such as bradykinesia, rigidity, and resting tremor. The name substantia nigra means “black substance,” reflecting neuromelanin pigment visible in many of its neurons.
The structure is not simply an on-off movement center. Its networks also participate in reinforcement learning and other functions. Dopamine is produced in several brain regions, so the substantia nigra should not be confused with the ventral tegmental area, another midbrain dopamine source.