Sensorimotor Performance Lab, Human Performance Research Centre, Department of Sport Science, University of Konstanz, Kinstanz, Germany.
Department of Kinesiology, Brock University, St Catharines, ON, Canada.
J Physiol. 2020 May;598(10):1943-1963. doi: 10.1113/JP278890. Epub 2020 Mar 27.
The spinal cord is an important contributor to motor learning It remains unclear whether short-term spinal cord adaptations are general or task-specific Immediately after task acquisition, neural adaptations were not specific to the trained task (i.e. were general) Twenty-four hours after acquisition, neural adaptations appeared to be task-specific The neural reorganization and generalization of spinal adaptations appears to be time-dependent.
Spinal cord plasticity is an important contributor of motor learning in humans, although its mechanisms are still poorly documented. In particular, it remains unclear whether short-term spinal adaptations are general or task-specific. As a marker of neural changes that are observable at spinal level, we measured the Hoffmann reflex (H-reflex) amplitude in the soleus muscle of 18 young healthy human adults before, immediately after (acquisition), and 24 h after (retention) the learning of a skilled task (i.e. one-legged stance on a tilt board). H-reflexes were elicited 46 ± 30 ms before touching the tilt board. Additionally, and at the same time points, we measured the H-reflex with the subject sitting at rest and when performing an unskilled and untrained task (i.e. one-legged stance on the floor). After task acquisition, there was a decrease of the H-reflex amplitude measured at rest but not during the skilled or the unskilled task. At retention, there was a decrease of the H-reflex when measured during the skilled task but not during the unskilled task or at rest. Performance increase was not associated with changes in the H-reflex amplitude. After the acquisition of a new skilled task, spinal changes appeared to be general (i.e. observable at rest). However, 24 h after, these changes were task-specific (i.e. observable only during performance of the trained task). These results imply that skill training induces a time-dependent reorganization of the modulation of spinal networks, which possibly reflects a time-dependent optimization of the feedforward motor command.
脊髓是运动学习的重要贡献者。短期脊髓适应是普遍的还是特定于任务的，目前尚不清楚。在任务获得后立即，神经适应不是特定于训练任务的（即普遍的）。获得后 24 小时，神经适应似乎是特定于任务的。脊髓适应的神经重组和泛化似乎是时间依赖性的。
脊髓可塑性是人类运动学习的重要贡献者，尽管其机制仍知之甚少。特别是，短期脊髓适应是普遍的还是特定于任务的，目前仍不清楚。作为可在脊髓水平观察到的神经变化的标志物，我们在 18 名年轻健康的成年人学习熟练任务（即在倾斜板上单腿站立）之前、立即（获得）和之后 24 小时（保留）测量了比目鱼肌的 Hoffmann 反射（H-反射）幅度。H-反射在接触倾斜板前 46±30 毫秒被引发。此外，在相同的时间点，我们在受试者坐着休息时和执行非熟练和未训练任务（即地板上单腿站立）时测量 H-反射。在任务获得后，在休息时测量的 H-反射幅度减小，但在熟练或非熟练任务时不减小。在保留期，在熟练任务中测量时 H-反射幅度减小，但在非熟练任务或休息时不减小。性能提高与 H-反射幅度的变化无关。在获得新的熟练任务后，脊髓变化似乎是普遍的（即可在休息时观察到）。然而，24 小时后，这些变化是特定于任务的（即在仅在执行训练任务时才观察到）。这些结果表明，技能训练会导致脊髓网络调制的时间依赖性重组，这可能反映了前馈运动指令的时间依赖性优化。
