The border between the SNpc and SNpr is highly convoluted with deep fringes. Its neuronal genus is the same as that of the pallidum, with the same thick and long dendritic trees. It receives its synapses from the striatum in the same way as the pallidum. Striatonigral axons from the striosomes may form columns vertically oriented entering deeply in the SNpr. The ventral dendrites of the SNpc from the reverse direction go also deeply in it. The SN also send axons to the pedunculopontine nucleus. and to the parafascicular part of the central complex. The SNpr is another "fast-spiking pacemaker" Stimulations provoke no movements. Confirming anatomical data, few neurons respond to passive and active movements (there is no sensorimotor map) "but a large proportion shows responses that may be related to memory, attention or movement preparation" that would correspond to a more elaborate level than that of the medial pallidum. In addition to the massive striatopallidal connection, the SNpr receives a dopamine innervation from the SNpc and glutamatergic axons from the pars parafascicularis of the central complex. It sends nigro-thalamic axons. There is no conspicuous nigro-thalamic bundle. Axons arrive medially to the pallidal afferences at the anterior and most medial part of the lateral region of the thalamus: the ventral anterior nucleus (VA) differentiated from the ventral lateral nucleus (VL) receiving pallidal afferences. The mediator is GABA.