Mari Stephen, Lecomte Charly G, Merlet Angèle N, Audet Johannie, Harnie Jonathan, Rybak Ilya A, Prilutsky Boris I, Frigon Alain
Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada.
Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.
Front Syst Neurosci. 2023 Jun 9;17:1199079. doi: 10.3389/fnsys.2023.1199079. eCollection 2023.
During locomotion, cutaneous reflexes play an essential role in rapidly responding to an external perturbation, for example, to prevent a fall when the foot contacts an obstacle. In cats and humans, cutaneous reflexes involve all four limbs and are task- and phase modulated to generate functionally appropriate whole-body responses.
To assess task-dependent modulation of cutaneous interlimb reflexes, we electrically stimulated the superficial radial or superficial peroneal nerves in adult cats and recorded muscle activity in the four limbs during tied-belt (equal left-right speeds) and split-belt (different left-right speeds) locomotion.
We show that the pattern of intra- and interlimb cutaneous reflexes in fore- and hindlimbs muscles and their phase-dependent modulation were conserved during tied-belt and split-belt locomotion. Short-latency cutaneous reflex responses to muscles of the stimulated limb were more likely to be evoked and phase-modulated when compared to muscles in the other limbs. In some muscles, the degree of reflex modulation was significantly reduced during split-belt locomotion compared to tied-belt conditions. Split-belt locomotion increased the step-by-step variability of left-right symmetry, particularly spatially.
These results suggest that sensory signals related to left-right symmetry reduce cutaneous reflex modulation, potentially to avoid destabilizing an unstable pattern.
在运动过程中，皮肤反射在快速应对外部干扰方面起着至关重要的作用，例如，当脚碰到障碍物时防止摔倒。在猫和人类中，皮肤反射涉及所有四肢，并且会根据任务和阶段进行调节，以产生功能上合适的全身反应。
为了评估皮肤肢体间反射的任务依赖性调节，我们对成年猫的桡浅神经或腓浅神经进行电刺激，并在系腰带（左右速度相等）和分腰带（左右速度不同）运动期间记录四肢的肌肉活动。
我们发现，在系腰带和分腰带运动期间，前肢和后肢肌肉的肢体内部和肢体间皮肤反射模式及其相位依赖性调节是保守的。与其他肢体的肌肉相比，受刺激肢体肌肉的短潜伏期皮肤反射反应更有可能被诱发并进行相位调节。在某些肌肉中，与系腰带条件相比，分腰带运动期间反射调节程度显著降低。分腰带运动增加了左右对称性的逐步步态变异性，尤其是在空间上。
这些结果表明，与左右对称性相关的感觉信号会降低皮肤反射调节，这可能是为了避免破坏不稳定模式的稳定性。
