How does the substantia nigra supply dopamine to the caudate nucleus and putamen?

The substantia nigra supplies dopamine to the caudate nucleus and putamen through the pars compacta, a specific region of the substantia nigra containing neurons that synthesize dopamine.1

These dopaminergic neurons project directly to the caudate nucleus and putamen, which together form the dorsal striatum. By releasing pulses of dopamine into the striatum, these neurons act as gatekeepers that modulate the activity of spiny striatal neurons. Specifically, dopamine influences the output of the inhibitory neurotransmitter GABA from these striatal cells, thereby helping to fine-tune motor control, reinforce specific behavioral pathways, and facilitate the learning of actions. This nigrostriatal pathway is essential for the regulation of voluntary movement.12345