Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA.
Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA.
Neuron. 2019 Nov 20;104(4):765-780.e3. doi: 10.1016/j.neuron.2019.08.032. Epub 2019 Oct 3.
How do neurons in orofacial motor cortex (MCtx) orchestrate behaviors? We show that focal activation of MCtx corticobulbar neurons evokes behaviorally relevant concurrent movements of the forelimb, jaw, nose, and vibrissae. The projections from different locations in MCtx form gradients of boutons across premotor nuclei spinal trigeminal pars oralis (SpVO) and interpolaris rostralis (SpVIr). Furthermore, retrograde viral tracing from muscles that control orofacial actions shows that these premotor nuclei segregate their outputs. In the most dramatic case, both SpVO and SpVIr are premotor to forelimb and vibrissa muscles, while only SpVO is premotor to jaw muscles. Functional confirmation of the superimposed control by MCtx was obtained through selective optogenetic activation of corticobulbar neurons on the basis of their preferential projections to SpVO versus SpVIr. We conclude that neighboring projection neurons in orofacial MCtx form parallel pathways to distinct pools of trigeminal premotor neurons that coordinate motor actions into a behavior.
口腔运动皮层（MCtx）中的神经元如何协调行为？我们发现，MCtx 皮质延髓神经元的局部激活会引发前肢、颌、鼻和触须的行为相关的并发运动。来自 MCtx 不同位置的投射在运动前核脊髓三叉神经前腹核（SpVO）和中间棘状腹核（SpVIr）中形成了一连串的终末。此外，来自控制口腔运动的肌肉的逆行病毒追踪显示，这些运动前核将它们的输出分开。在最显著的情况下，SpVO 和 SpVIr 都是前肢和触须肌肉的运动前核，而只有 SpVO 是颌部肌肉的运动前核。通过基于其对 SpVO 与 SpVIr 的优先投射选择性光遗传激活皮质延髓神经元，对 MCtx 的叠加控制进行了功能确认。我们的结论是，口腔 MCtx 中的相邻投射神经元形成了平行的通路，分别连接到不同的三叉神经运动前神经元池，协调运动行为。
