Musienko Pavel E, Lyalka Vladimir F, Gorskii Oleg V, Zelenin Pavel V, Deliagina Tatiana G
Laboratory of Neuroprosthetics, Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia.
Laboratory of Motor and Visceral Functions Neuromodulation, Pavlov Institute of Physiology, St. Petersburg 199034, Russia.
J Neurosci. 2022 Apr 27;42(17):3570-3586. doi: 10.1523/JNEUROSCI.1884-21.2022. Epub 2022 Mar 16.
Higher vertebrates are capable not only of forward but also backward and sideways locomotion. Also, single steps in different directions are generated for postural corrections. While the networks responsible for the control of forward walking (FW) have been studied in considerable detail, the networks controlling steps in other directions are mostly unknown. Here, to characterize the operation of the spinal locomotor network during FW and backward walking (BW), we recorded the activity of individual spinal interneurons from L4 to L6 during both FW and BW evoked by epidural stimulation (ES) of the spinal cord at L5-L6 in decerebrate cats of either sex. Three groups of neurons were revealed. Group 1 (45%) had a similar phase of modulation during both FW and BW. Group 2 (27%) changed the phase of modulation in the locomotor cycle depending on the direction of locomotion. Group 3 neurons were modulated during FW only (Group 3a, 21%) or during BW only (Group 3b, 7%). We suggest that Group 1 neurons belong to the network generating the vertical component of steps (the limb elevation and lowering) because it should operate similarly during locomotion in any direction, while Groups 2 and 3 neurons belong to the networks controlling the direction of stepping. Results of this study provide new insights into the organization of the spinal locomotor circuits, advance our understanding of ES therapeutic effects, and can potentially be used for the development of novel strategies for recuperation of impaired balance control, which requires the generation of corrective steps in different directions. Animals and humans can perform locomotion in different directions in relation to the body axis (forward, backward, sideways). While the networks that control forward walking have been studied in considerable detail, the networks controlling steps in other directions are unknown. Here, by recording the activity of the same spinal neurons during forward and backward walking, we revealed three groups of neurons forming, respectively, the network operating similarly during stepping in different directions, the network changing its operation with a change in the direction of stepping, and the network operating only during locomotion in a specific direction. These networks presumably control different aspects of the step. The obtained results provide new insights into the organization of the spinal locomotor networks.
高等脊椎动物不仅能够向前移动，还能向后和向侧面移动。此外，还会产生不同方向的单步动作以进行姿势校正。虽然负责控制向前行走（FW）的神经网络已得到相当详细的研究，但控制其他方向步行动作的神经网络大多仍不为人知。在此，为了描述脊髓运动神经网络在FW和向后行走（BW）过程中的运作情况，我们在去大脑的雌雄猫中，通过对L5-L6脊髓节段进行硬膜外刺激（ES）诱发FW和BW，记录了L4至L6节段单个脊髓中间神经元的活动。我们发现了三组神经元。第1组（45%）在FW和BW过程中具有相似的调制相位。第2组（27%）根据运动方向改变运动周期中的调制相位。第3组神经元仅在FW过程中受到调制（第3a组，21%）或仅在BW过程中受到调制（第3b组，7%）。我们认为第1组神经元属于产生步行动作垂直分量（肢体抬起和放下）的神经网络，因为它在任何方向的运动过程中都应类似地运作，而第2组和第3组神经元属于控制步行动作方向的神经网络。本研究结果为脊髓运动回路的组织提供了新的见解，推进了我们对ES治疗效果的理解，并有可能用于开发恢复受损平衡控制的新策略，这需要产生不同方向的校正步行动作。动物和人类可以相对于身体轴线在不同方向上进行移动（向前、向后、向侧面）。虽然控制向前行走的神经网络已得到相当详细的研究，但控制其他方向步行动作的神经网络仍不为人知。在此，通过记录同一脊髓神经元在向前和向后行走过程中的活动，我们发现了三组神经元，它们分别形成了在不同方向步行动作过程中运作相似的神经网络、随着步行动作方向改变而改变其运作的神经网络以及仅在特定方向运动过程中运作的神经网络。这些神经网络大概控制步行动作的不同方面。所获得的结果为脊髓运动神经网络的组织提供了新的见解。
