Cognitive Motor Neuroscience, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
J Appl Physiol (1985). 2024 Apr 1;136(4):807-820. doi: 10.1152/japplphysiol.00821.2023. Epub 2024 Feb 15.
Although attentional focus affects motor performance, whether corticospinal excitability and intracortical modulations differ between focus strategies depending on the exercise patterns remains unclear. In the present study, using single- and paired-pulse transcranial magnetic stimulation and peripheral nerve stimulation, we demonstrated changes in the cortical and spinal excitability under external focus (EF) and internal focus (IF) conditions with dynamic or static exercise. Participants performed the ramp-and-hold contraction task of right index finger abduction against an object (sponge or wood) with both exercises. They were asked to concentrate on the pressure on the sponge/wood induced by finger abduction under the EF condition, and on the index finger itself under the IF condition. Motor-evoked potential (MEP) and F-wave in the premotor, phasic, or tonic phase, and short- and long-interval intracortical inhibition (SICI and LICI, respectively), and intracortical facilitation (ICF) in the premotor phase were examined by recording surface electromyographic activity in the right first dorsal interosseous muscle. Increments in the MEP amplitude were larger under the EF condition than under the IF condition in the dynamic, but not static, exercise. The F-wave, SICI, and LICI did not differ between focus conditions in both exercises. In the dynamic exercise, interestingly, ICF was greater under the EF condition than under the IF condition and positively correlated with the MEP amplitude. These results indicate that corticospinal excitability and intracortical modulations to attentional focus differ depending on exercise patterns, suggesting that attentional focus differentially affects the central nervous system responsible for diverse motor behaviors. We investigated attentional focus-dependent corticospinal and intracortical modulations in dynamic or static exercise. The corticospinal excitability was modulated differentially depending on the focus of attention during dynamic, but not static exercise. Although the reduction of intracortical GABAergic inhibition was comparable between focus conditions in both exercises, intracortical facilitation was smaller when focusing on the internal environments in the dynamic exercise, resulting in lower activation of the corticospinal tract.
虽然注意力集中会影响运动表现，但取决于运动模式，注意策略是否会导致皮质脊髓兴奋性和皮质内调制不同仍不清楚。在本研究中，我们使用单脉冲和双脉冲经颅磁刺激和外周神经刺激，在动态或静态运动下，展示了外部焦点（EF）和内部焦点（IF）条件下皮质和脊髓兴奋性的变化。参与者使用两种运动进行右食指外展对抗物体（海绵或木头）的斜坡和保持收缩任务。他们被要求在 EF 条件下专注于食指外展引起的海绵/木头的压力，在 IF 条件下专注于食指本身。通过记录右第一背间骨间肌的表面肌电图活动，检查运动诱发电位（MEP）和在运动相、相性或紧张相的 F 波，以及短程和长程皮质内抑制（SICI 和 LICI）和运动相的皮质内易化（ICF）。在动态运动中，MEP 幅度的增量在 EF 条件下大于 IF 条件，但在静态运动中则不然。在两种运动中，焦点条件之间的 F 波、SICI 和 LICI 没有差异。有趣的是，在动态运动中，ICF 在 EF 条件下大于 IF 条件，与 MEP 幅度呈正相关。这些结果表明，皮质脊髓兴奋性和皮质内调制对注意力集中的影响取决于运动模式，这表明注意力集中会以不同的方式影响负责不同运动行为的中枢神经系统。我们研究了动态或静态运动中注意力集中依赖性的皮质脊髓和皮质内调制。在动态运动中，皮质脊髓兴奋性根据注意力集中的焦点而不同地调节，但在静态运动中则不然。尽管两种运动中焦点条件之间的皮质内 GABA 能抑制的减少是可比的，但在动态运动中，当内部环境聚焦时，皮质内易化较小，导致皮质脊髓束的激活较低。
