Movement Neuroscience Laboratory, Department of Exercise Sciences, The University of Auckland, Auckland, New Zealand.
Centre for Brain Research, The University of Auckland, Auckland, New Zealand.
J Neurophysiol. 2019 Oct 1;122(4):1357-1366. doi: 10.1152/jn.00310.2019. Epub 2019 Jul 24.
Response inhibition reflects the process of terminating inappropriate preplanned or ongoing movements. When one hand is cued to stop after preparing a bimanual response (Partial trial), there is a substantial delay on the responding side. This delay is termed the interference effect and identifies a constraint that limits selective response inhibition. γ-Aminobutyric acid (GABA)-mediated networks within primary motor cortex (M1) may have distinct roles during response inhibition. In this study we examined whether the interference effect is the consequence of between-hand "coupling" into a unitary response and whether this is reflected in GABAergic intracortical inhibition within M1. Eighteen healthy right-handed participants performed a bimanual synchronous and asynchronous anticipatory response inhibition task. Electromyographic recordings were obtained from the first dorsal interosseous muscle bilaterally. Motor evoked potentials were elicited by single- and paired-pulse transcranial magnetic stimulation over right M1. As expected, Go trial performance was better with the synchronous compared with the asynchronous version of the task. Paradoxically, response delays during Partial trials were longer with the synchronous compared with the asynchronous task. Although task difficulty did not modulate GABAergic intracortical inhibition, there was a trend for between-hand coupling on asynchronous trials to be associated with greater GABA receptor-mediated inhibition and lesser recruitment of GABA receptor-mediated inhibition. The novel findings indicate that the interference effect is in part a consequence of between-hand coupling into a unitary response during movement preparation. The ability to respond independently with the two hands may rely on modulation of distinct inhibitory processes. The temporal dynamics of an anticipated response task were manipulated to effect the difficulty of behavioral stopping and the underlying effects on motor neurophysiology. There were large response delays during trials where a subcomponent of an upcoming bimanual response was cued to stop in conditions where the anticipated action of the hands were synchronous, but not when asynchronous. Response delays reflected the integration of actions of both hands into a unitary response.
反应抑制反映了终止不适当的预计划或正在进行的运动的过程。当一只手在准备双手反应（部分试验）后被提示停止时，响应侧会有很大的延迟。这种延迟称为干扰效应，并确定了限制选择性反应抑制的约束。γ-氨基丁酸（GABA）介导的初级运动皮层（M1）内的网络在反应抑制中可能具有不同的作用。在这项研究中，我们研究了干扰效应是否是双手之间“耦合”到单一反应的结果，以及这是否反映在 M1 内的 GABA 能皮质内抑制中。18 名健康的右利手参与者进行了双手同步和异步预期反应抑制任务。双侧第一背侧骨间肌记录肌电图。通过单脉冲和双脉冲经颅磁刺激在右 M1 上诱发运动诱发电位。正如预期的那样，与异步版本相比，同步版本的 Go 试验表现更好。矛盾的是，与异步任务相比，部分试验中的反应延迟更长。尽管任务难度不会调节 GABA 能皮质内抑制，但在异步试验中，双手之间的耦合与更大的 GABA 受体介导的抑制和更少的 GABA 受体介导的抑制有关。新的发现表明，干扰效应在一定程度上是运动准备过程中双手之间耦合到单一反应的结果。用两只手独立反应的能力可能依赖于对不同抑制过程的调节。通过操纵预期反应任务的时间动态来影响行为停止的难度和对运动神经生理学的潜在影响。在即将进行的双手反应的子组件被提示停止的情况下，即双手的预期动作同步，但不是异步的情况下，试验中的反应延迟很大。反应延迟反映了双手动作的整合到一个单一的反应。
