School of Psychology, University of Sydney, Australia.
School of Psychology, University of Sydney, Australia.
Neuroscience. 2019 Sep 15;416:1-8. doi: 10.1016/j.neuroscience.2019.07.038. Epub 2019 Jul 27.
Response inhibition - the suppression of prepotent behaviours when they are inappropriate - has been thought to rely on executive control. Against this received wisdom, it has been argued that external cues repeatedly associated with response inhibition can come to trigger response inhibition automatically without top-down command. The current project endeavoured to provide evidence for associatively-mediated motor inhibition. We tested the hypothesis that stop-associated stimuli can, in a bottom-up fashion, directly activate inhibitory mechanisms in the motor cortex. Human subjects were first trained on a stop-signal task. Once trained, the subjects received transcranial magnetic stimulation applied over their primary motor cortex during passive observation of either the stop signal (i.e. without any need to stop a response) or an equally familiar control stimulus never associated with stopping. Analysis of motor-evoked potentials showed that corticospinal excitability was reduced during exposure to the stop signal, which likely involved stimulus-driven activation of intracortical GABAergic interneurons. This result provides evidence that, through associative learning, stop-associated stimuli can engage local inhibitory processes at the level of the motor cortex.
反应抑制——当行为不当时抑制优势行为——被认为依赖于执行控制。与这种传统观点相反，有人认为，与反应抑制反复相关联的外部线索可以自动触发反应抑制，而无需自上而下的命令。当前的项目旨在为联想介导的运动抑制提供证据。我们测试了以下假设：与停止相关的刺激可以以自下而上的方式直接激活运动皮层中的抑制机制。首先，人类受试者在停止信号任务上接受训练。一旦接受训练，受试者在被动观察停止信号（即无需停止反应）或从未与停止相关联的同样熟悉的控制刺激时，接受经颅磁刺激（TMS）应用于初级运动皮层。运动诱发电位的分析表明，在暴露于停止信号期间，皮质脊髓兴奋性降低，这可能涉及到刺激驱动的抑制性中间神经元的兴奋。该结果表明，通过联想学习，与停止相关的刺激可以在运动皮层水平上引发局部抑制过程。
