PDF(Pubmed)
Abstract：
The acquisition of a motor skill involves adaptations of spinal and supraspinal pathways to alpha motoneurons. In this study, we estimated the shared synaptic contributions of these pathways to understand the neural mechanisms underlying the short-term acquisition of a new force-matching task. High-density surface electromyography (HDsEMG) was acquired from the first dorsal interosseous (FDI; 7 males and 6 females) and tibialis anterior (TA; 7 males and 4 females) during 15 trials of an isometric force-matching task. For two selected trials (pre- and post-skill acquisition), we decomposed the HDsEMG into motor unit spike trains, tracked motor units between trials, and calculated the mean discharge rate and the coefficient of variation of interspike interval (COVISI). We also quantified the post/pre ratio of motor units\' coherence within delta, alpha, and beta bands. Force-matching improvements were accompanied by increased mean discharge rate and decreased COVISI for both muscles. Moreover, the area under the curve within alpha band decreased by ∼22% (TA) and ∼13% (FDI), with no delta or beta bands changes. These reductions correlated significantly with increased coupling between force/neural drive and target oscillations. These results suggest that short-term force-matching skill acquisition is mediated by attenuation of physiological tremor oscillations in the shared synaptic inputs. Supported by simulations, a plausible mechanism for alpha band reductions may involve spinal interneuron phase-cancelling descending oscillations. Therefore, during skill learning, the central nervous system acts as a matched filter, adjusting synaptic weights of shared inputs to suppress neural components unrelated to the specific task.
摘要：
运动技能的获得涉及脊柱和脊柱上途径对α运动神经元的适应。在这项研究中,我们估计了这些通路的共有突触贡献,以了解短期获得新的力匹配任务的潜在神经机制.在15项等距力匹配任务的试验中，从第一个背侧骨间（FDI；7名男性和6名女性）和胫骨前肌（TA；7名男性和4名女性）获得了高密度表面肌电图（HDsEMG）。对于两个选定的试验(技能获取前和技能获取后)，我们将HDsEMG分解为电机单元尖峰列车，在试验之间跟踪电机单元，并计算平均放电率和尖峰间期变异系数(CoVISI)。我们还量化了增量内运动单位一致性的后/前比率，阿尔法，和贝塔乐队。力匹配的改善伴随着平均放电率的增加和两条肌肉CoVISI的降低。此外，阿尔法带内的曲线下面积减少了22%(TA)和13%(FDI)，没有δ或β带变化。这些减少与力/神经驱动和目标振荡之间的耦合增加显着相关。这些结果表明，短期力匹配技能的获取是由共享突触输入中生理震颤振荡的衰减所介导的。在模拟的支持下，α带减少的一个合理机制可能涉及脊髓中间神经元相位抵消下降振荡。因此,在技能学习期间，中枢神经系统作为一个匹配的过滤器，调整共享输入的突触权重，以抑制与特定任务无关的神经成分。以前的研究已经提出，只有共享的突触输入到运动神经元的低频振荡，包括与任务相关和与任务无关的振荡，负责产生的肌肉力量。在我们的研究中,我们调查了涉及精确力产生的新运动任务的获取是否需要在这些共享的突触输入中进行特定的改变.我们的研究结果表明,手部肌肉和腿部肌肉，技能获取是由与所需力波动无关的共享突触振荡的减少介导的(即，生理震颤带振荡)。因此,在力量匹配任务学习期间，中枢神经系统就像神经过滤器，调制共享输入的突触权重以衰减与特定任务无关的神经成分。
