Department of Neuroscience, UT Southwestern Medical Center, Dallas, Texas 75390.
Department of Neuroscience, UT Southwestern Medical Center, Dallas, Texas 75390
eNeuro. 2024 Apr 26;11(4). doi: 10.1523/ENEURO.0331-23.2024. Print 2024 Apr.
Proprioception, the sense of limb and body position, is required to produce accurate and precise movements. Proprioceptive sensory neurons transmit muscle length and tension information to the spinal cord. The function of excitatory neurons in the intermediate spinal cord, which receive this proprioceptive information, remains poorly understood. Using genetic labeling strategies and patch-clamp techniques in acute spinal cord preparations in mice, we set out to uncover how two sets of spinal neurons, Clarke's column (CC) and -lineage neurons, respond to electrical activity and how their inputs are organized. Both sets of neurons are located in close proximity in laminae V-VII of the thoracolumbar spinal cord and have been described to receive proprioceptive signals. We find that a majority of CC neurons have a tonic-firing type and express a distinctive hyperpolarization-activated current (I). -lineage neurons, which cluster into two spatially distinct populations, are mostly a fading-firing type and display similar electrophysiological properties to each other, possibly due to their common developmental lineage. Finally, we find that CC neurons respond to stimulation of lumbar dorsal roots, consistent with prior knowledge that CC neurons receive hindlimb proprioceptive information. In contrast, using a combination of electrical stimulation, optogenetic stimulation, and transsynaptic rabies virus tracing, we find that -lineage neurons receive heterogeneous, predominantly local thoracic inputs that include parvalbumin-lineage sensory afferents and local interneuron presynaptic inputs. Altogether, we find that CC and -lineage neurons have distinct membrane properties and sensory input organization, representing different subcircuit modes of proprioceptive information processing.
本体感觉，即肢体和身体位置的感觉，是产生准确和精确运动所必需的。本体感觉感觉神经元将肌肉长度和张力信息传递到脊髓。中间脊髓中兴奋性神经元的功能，接收这种本体感觉信息，仍然知之甚少。我们使用遗传标记策略和在小鼠急性脊髓制剂中使用膜片钳技术，旨在揭示两组脊髓神经元，即 Clarke 柱（CC）和 - 谱系神经元，如何对电活动做出反应，以及它们的输入是如何组织的。这两组神经元都位于胸腰椎脊髓的 V-VII 层附近，并且已经被描述为接收本体感觉信号。我们发现，大多数 CC 神经元具有紧张型放电类型，并表达独特的超极化激活电流（I）。- 谱系神经元簇成两个空间上不同的群体，主要是渐弱型放电类型，彼此之间显示出相似的电生理特性，可能是由于它们共同的发育谱系。最后，我们发现 CC 神经元对腰背部神经根的刺激有反应，这与 CC 神经元接收后肢本体感觉信息的先前知识一致。相比之下，我们使用电刺激、光遗传学刺激和跨突触狂犬病毒追踪的组合，发现 - 谱系神经元接收异质的、主要是局部胸内输入，包括副球蛋白谱系感觉传入和局部中间神经元的突触前输入。总的来说，我们发现 CC 和 - 谱系神经元具有不同的膜特性和感觉输入组织，代表了本体感觉信息处理的不同亚电路模式。
