Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
Neuron. 2013 Jan 23;77(2):346-60. doi: 10.1016/j.neuron.2012.11.010.
Rodents begin to use bilaterally coordinated, rhythmic sweeping of their vibrissae ("whisking") for environmental exploration around 2 weeks after birth. Whether (and how) the vibrissal control circuitry changes after birth is unknown, and the relevant premotor circuitry remains poorly characterized. Using a modified rabies virus transsynaptic tracing strategy, we labeled neurons synapsing directly onto vibrissa facial motor neurons (vFMNs). Sources of potential excitatory, inhibitory, and modulatory vFMN premotor neurons, and differences between the premotor circuitry for vFMNs innervating intrinsic versus extrinsic vibrissal muscles were systematically characterized. The emergence of whisking is accompanied by the addition of new sets of bilateral excitatory inputs to vFMNs from neurons in the lateral paragigantocellularis (LPGi). Furthermore, descending axons from the motor cortex directly innervate LPGi premotor neurons. Thus, neural modules that are well suited to facilitate the bilateral coordination and cortical control of whisking are added to the premotor circuitry in parallel with the emergence of this exploratory behavior.
啮齿动物在出生后大约 2 周开始使用双侧协调、有节奏的触须（“扫动”）进行环境探索。出生后触须控制回路是否（以及如何）发生变化尚不清楚，相关的运动前回路仍未得到很好的描述。我们使用改良的狂犬病毒顺行转染追踪策略，标记了直接与触须面运动神经元（vFMN）突触的神经元。我们系统地描述了 vFMN 的潜在兴奋性、抑制性和调制性运动前神经元的来源，以及支配内在和外在触须肌的 vFMN 运动前回路之间的差异。出现扫动伴随着来自外侧巨细胞旁核（LPGi）的神经元向 vFMN 添加新的双侧兴奋性输入。此外，来自运动皮层的下行轴突直接支配 LPGi 运动前神经元。因此，与这种探索行为同时出现的是，能够促进双侧协调和皮层控制的神经模块被添加到运动前回路中。
