Function
The neurons of the pars reticulata are fast-spiking pacemakers, generating action potentials in the absence of synaptic input. In primates they discharge at a mean rate of 68Hz in contrast to dopaminergic neurons (below 8Hz). They receive abundant afferrences from the striatum (mainly from the associative striatum) with the same very peculiar synaptology as the pallidum. It receives axons from the subthalamic nucleus and a dopaminergic innervation from the dopaminergic ensemble.
The pars reticulata is one of the two primary output nuclei of the basal ganglia system to the motor thalamus (the other output is the internal segment of the globus pallidus).The nigral neurons have their own territory distinct from the cerebellar and the pallidal in the nucleus ventralis anterior VA. This sends axons to the frontal and oculomotor cortex. Hikosaka and Wurtz devoted four papers to "the visual and oculomotor functions of the monkey substantia nigra pars reticulata". This is largely involved in orientation and the control of eye movements in stabilisation of gaze and in saccades.
Read more about this topic: Pars Reticulata
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