Anatomical connections of the ventral, but not the dorsal part of the striatum with the parvicellular reticular formation: Implications for the anatomical substrate of oral movements

Using a double labelling procedure by combining injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin into different parts of the striatum with injections of the retrograde tracer choleratoxin subunit B into the parvicellular reticular formation of rats (pcRF), it was found that the ventrolateral part of the striatum (vlS) projects onto neurons in the dorsolateral part of the substantia nigra pars reticulata (SNR), a region that, in turn, was found to project to the pcRF. In contrast, the dorsomedial part of the striatum (dmS) projects onto neurons in the ventrolateral part of the SNR, a region that was found not to project to the pcRF. These differential striato-nigro-reticular pathways are discussed in view of the differential role of the vlS and dmS in the expression of oral movements.