Functional neuroanatomy of masticatory control : Projections from cortical masticatory areas to basal ganglia

我们研究了连接猴子额叶多个下颌运动相关区域和三叉神经运动核（Vm）前运动神经元池的平行通路的组织。我们的皮质内微刺激映射揭示了以下三个皮质区域的存在，其中刺激引起下颌运动：初级运动皮质的口面部区域、辅助运动区域的口面部区域和皮质咀嚼区域的主要部分。这些与下颌运动相关的区域不仅直接向外侧被盖区（Vm 前运动神经元的主要部位）发送投射，并且在 Vm 周围区域中密度最高，而且还间接通过基底神经节发送投射。在基底神经节中，壳核的腹侧接收来自下颌运动相关区域的皮质纹状体输入，然后分别将纹状体苍白球和纹状体黑质输出发送到苍白球内段的腹侧或黑质网状部的背侧。然后，苍白球和黑质的直接投影终止于外侧被盖区。这种平行通路可能通过前运动神经元对 Vm 施加不同的调节作用。

We investigated the organization of parallel pathways connecting multiple jaw movement-related areas of the frontal lobe and the premotor neuron pool for the trigeminal motor nucleus (Vm) in the monkey. Our intracortical microstimulation mapping has revealed the existence of the following three cortical areas of which stimulation evokes jaw movements : the orofacial region of the primary motor cortex, the orofacial region of the supplementary motor area and the principal part of the cortical masticatory area. These jaw movement-related areas send projections not only directly to the lateral tegmental field-the major site of Vm premotor neurons-with the highest density in the regions surrounding the Vm, but also indirectly via the basal ganglia. In the basal ganglia, the ventral aspect of the putamen receives corticostriatal inputs from the jaw movement-related areas and, in turn, sends striatopallidal and striatonigral outputs to the ventral aspect of the internal segment of the globus pallidus or to the dorsal aspect of the substantia nigra pars reticulata, respectively. Then, direct projections from the globus pallidus and the substantia nigra terminate in the lateral tegmental field. Such parallel pathways may exert differential modulatory effects on the Vm via the premotor neurons.