Dopamine modulation

The dopaminergic neurons of the substantia nigra pars compacta (SNpc) modify their firing prototype in reaction to stimuli which reward a movement. They modulate the reaction of medium spiny neurons in the striatum to corticostriate inputs but have reverse effects on the two populations. Whereas the GABA/SP/DYN neurons are made more excitable, while the GABA/ENK cells become less excitable in the face of SNpc inputs. In synopsis, the direct pathway is improved by, and the indirect pathway concealed by, the nigrostriatal tract from the SNpc.