Howard Hughes Medical Institute, Kavli Institute for Brain Science, Department of Neuroscience, Columbia University, New York, NY 10032, USA.
Neuron. 2009 Dec 10;64(5):645-62. doi: 10.1016/j.neuron.2009.10.017.
Mammalian motor programs are controlled by networks of spinal interneurons that set the rhythm and intensity of motor neuron firing. Motor neurons have long been known to receive prominent "C bouton" cholinergic inputs from spinal interneurons, but the source and function of these synaptic inputs have remained obscure. We show here that the transcription factor Pitx2 marks a small cluster of spinal cholinergic interneurons, V0(C) neurons, that represents the sole source of C bouton inputs to motor neurons. The activity of these cholinergic interneurons is tightly phase locked with motor neuron bursting during fictive locomotor activity, suggesting a role in the modulation of motor neuron firing frequency. Genetic inactivation of the output of these neurons impairs a locomotor task-dependent increase in motor neuron firing and muscle activation. Thus, V0(C) interneurons represent a defined class of spinal cholinergic interneurons with an intrinsic neuromodulatory role in the control of locomotor behavior.
哺乳动物的运动程序由脊髓中间神经元网络控制，这些网络设定运动神经元放电的节律和强度。长期以来，运动神经元一直被认为会从脊髓中间神经元接收突出的“C 末梢”胆碱能输入，但这些突触输入的来源和功能仍不清楚。我们在这里表明，转录因子 Pitx2 标记了一小群脊髓胆碱能中间神经元，即 V0(C)神经元，它们是运动神经元 C 末梢输入的唯一来源。在虚拟运动活动期间，这些胆碱能中间神经元的活动与运动神经元爆发紧密地相位锁定，这表明它们在调节运动神经元放电频率方面具有重要作用。这些神经元输出的遗传失活会损害运动神经元放电和肌肉激活的运动任务依赖性增加。因此，V0(C)中间神经元代表了一类特定的脊髓胆碱能中间神经元，它们在控制运动行为方面具有内在的神经调制作用。
