Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada; Sobell Department of Neuromuscular Diseases, Institute of Neurology, University College London, London WC1N 3BG, UK.
Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
Cell Rep. 2018 Oct 2;25(1):146-156.e3. doi: 10.1016/j.celrep.2018.08.095.
Layering of neural circuits facilitates the separation of neurons with high spatial sensitivity from those that play integrative temporal roles. Although anatomical layers are readily identifiable in the brain, layering is not structurally obvious in the spinal cord. But computational studies of motor behaviors have led to the concept of layered processing in the spinal cord. It has been postulated that spinal V3 interneurons (INs) play multiple roles in locomotion, leading us to investigate whether they form layered microcircuits. Using patch-clamp recordings in combination with holographic glutamate uncaging, we demonstrate focal, layered modules, in which ventromedial V3 INs form synapses with one another and with ventrolateral V3 INs, which in turn form synapses with ipsilateral motoneurons. Motoneurons, in turn, provide recurrent excitatory, glutamatergic input to V3 INs. Thus, ventral V3 interneurons form layered microcircuits that could function to ensure well-timed, spatially specific movements.
神经回路的分层有助于将具有高空间灵敏度的神经元与那些发挥综合时间作用的神经元区分开来。尽管大脑中的解剖层很容易识别,但脊髓中的分层结构并不明显。但是对运动行为的计算研究导致了脊髓中分层处理的概念。有人假设脊髓 V3 中间神经元(IN)在运动中发挥多种作用,这促使我们研究它们是否形成分层微电路。我们使用膜片钳记录与全息谷氨酸光解相结合的方法,证明了在腹侧 V3 IN 之间形成焦点分层模块,它们相互形成突触,与腹外侧 V3 IN 形成突触,而腹外侧 V3 IN 又与同侧运动神经元形成突触。运动神经元反过来又向 V3 IN 提供兴奋性谷氨酸能的回传输入。因此,腹侧 V3 中间神经元形成分层微电路,这些电路可以确保时间准确、空间特异性的运动。