 In the direct pathway, medium spiny neurons project to the internal division of the globus pallidus (GPi) or the substantia nigra pars reticula (SNpr or SNr).These nuclei project to the deep layer of the superior colliculus and control fast eye movements (saccades), and also project to the ventral thalamus, which in turn projects to upper motor neurons in the primary motor cortex (precentral gyrus).The SNr and GPi outputs are both tonically active inhibitory nuclei and are thus constantly inhibiting the thalamus (and thus motor cortex).