Department of Neurosciences and Movement Science, Faculty of Science and Medicine, University of Fribourg, Bd. De Pérolles 90, 1700, Fribourg, Switzerland.
Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland.
Sci Rep. 2021 Sep 9;11(1):17910. doi: 10.1038/s41598-021-97168-9.
The neurophysiological mechanisms underlying the behavioural improvements usually associated with an external (EF) compared with an internal focus of attention (IF) remain poorly investigated. Surround inhibition in the primary cortex has been shown to be more pronounced with an EF, indicating a more spatial restriction of the motor command. However, the influence of different foci on the temporal aspect of the motor command, such as the modulation of fast versus slow(er) motor pathways, remains unknown and was therefore investigated in this study. Fourteen participants were asked to press on a pedal with the right foot to match its position with a target line displayed on a screen. The deviation of the pedal from the target line was used as a behavioural parameter and compared between both foci (EF vs IF). Additionally, conditioned H-reflexes were evoked during the motor task to assess the excitability of fast (direct) and slower (more indirect) motor pathways when adopting an EF or IF. With an EF compared to an IF, the motor performance was enhanced (P = .001; + 24%) and the activation of slow(er) motor pathways was reduced (P < 0.001, - 11.73%). These findings demonstrate for the first time that using different attentional strategies (EF and IF) has an influence on the excitability of slow(er) motor pathways. Together with the increased intracortical inhibition and surround inhibition known from previous studies, the diminished activation in the slow(er) motor pathways further explains why using an EF is a more economic strategy.
与内部注意焦点 (IF) 相比，外部注意焦点 (EF) 通常与行为改善相关的神经生理机制仍未得到充分研究。初级皮层中的周围抑制已被证明在 EF 时更为明显，表明运动指令的空间限制更大。然而，不同焦点对运动指令的时间方面的影响，例如对快速与较慢（较慢）运动通路的调制，仍然未知，因此本研究对此进行了调查。本研究要求 14 名参与者用右脚踩踏板，使其位置与屏幕上显示的目标线匹配。踏板与目标线的偏差被用作行为参数，并在两种焦点（EF 与 IF）之间进行比较。此外，在运动任务期间诱发条件性 H 反射，以评估采用 EF 或 IF 时快速（直接）和较慢（更间接）运动通路的兴奋性。与 IF 相比，EF 时运动表现得到改善（P = .001；+24%），较慢（较慢）运动通路的激活减少（P < 0.001，-11.73%）。这些发现首次表明，使用不同的注意策略（EF 和 IF）会影响较慢（较慢）运动通路的兴奋性。结合先前研究中已知的皮层内抑制和周围抑制增加，较慢（较慢）运动通路的激活减少进一步解释了为什么使用 EF 是一种更经济的策略。
