Morphological experiments of the control of jaw movements in the forebrain

点击翻译按钮获取中文摘要

We have already indicated that the dorsolateral part of the substabtia nigra pars reticulata (SNr), which is one of the major output nuclei of the basal ganglia, plays an important role in the control of jaw movement. The rostroventral part of the lateral agranular cortex (AGi) and the ventrolateral part of the striatum have been known as the area involved in the control of orofacial movement, In the present study, we examined the possible pathways from the dorsolateral part of the SNr to the rostroventral part of the AGl and the ventrolateral part of the striatum relayed by the thalamus using a combined anterograde and retrograde tracing technique.We first showed that the dorsolateral part of the SNr sent projection fibers to the ventrolateral part of the parafascicular thalamic nucleus (PE). Secondly, we indicated the overlapping distributions of the nigral fibers and the PF neurons projecting to the rostroventral part of the AGl or to the ventrolateral part of the striatum in the ventrolateral part of the PF.This part of the PF contained not only some neurons projecting to the rostroventral part of the AGl, but also many neurons projecting to the ventrolateral part of the striatum. The nigral axon terminals made symmetrical synaptic contacts with the soma and dendrites of the PF neurons projecting to the AGl or to the striatum. Thus, the SNr-PF-AGl and SNr-PF-striatal pathways revealed by the present study may be involved in the control mechanism of orofacial motor functions.