Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, 33 Queen Square (Box 146), London, WC1N 3BG, UK.
Eur J Neurosci. 2014 Sep;40(5):2850-8. doi: 10.1111/ejn.12651. Epub 2014 Jun 19.
The link between basic physiology and its modulation by cognitive states, such as attention, is poorly understood. A significant association becomes apparent when patients with movement disorders describe experiences with changing their attention focus and the fundamental effect that this has on their motor symptoms. Moreover, frequently used mental strategies for treating such patients, e.g. with task-specific dystonia, widely lack laboratory-based knowledge about physiological mechanisms. In this largely unexplored field, we looked at how the locus of attention, when it changed between internal (locus hand) and external (visual target), influenced excitability in the primary motor cortex (M1) in healthy humans. Intriguingly, both internal and external attention had the capacity to change M1 excitability. Both led to a reduced stimulation-induced GABA-related inhibition and a change in motor evoked potential size, i.e. an overall increased M1 excitability. These previously unreported findings indicated: (i) that cognitive state differentially interacted with M1 physiology, (ii) that our view of distraction (attention locus shifted towards external or distant location), which is used as a prevention or management strategy for use-dependent motor disorders, is too simple and currently unsupported for clinical application, and (iii) the physiological state reached through attention modulation represents an alternative explanation for frequently reported electrophysiology findings in neuropsychiatric disorders, such as an aberrant inhibition.
基本生理机能与其认知状态调制之间的联系，例如注意力，理解得还不够充分。当运动障碍患者描述改变注意力焦点以及这对他们运动症状的根本影响时，就会出现明显的关联。此外，治疗此类患者的常用心理策略，例如与特定任务相关的肌张力障碍，广泛缺乏关于生理机制的基于实验室的知识。在这个大部分尚未开发的领域，我们观察了当注意力焦点在内部（手部位置）和外部（视觉目标）之间变化时，如何影响健康人的初级运动皮层（M1）的兴奋性。有趣的是，内部和外部注意力都有改变 M1 兴奋性的能力。两者均导致刺激诱导的 GABA 相关抑制减少，运动诱发电位大小改变，即 M1 兴奋性整体增加。这些以前未报道的发现表明：（i）认知状态与 M1 生理学有差异地相互作用，（ii）我们对分心的看法（注意力焦点转移到外部或远处），用作使用依赖性运动障碍的预防或管理策略，过于简单，目前不支持临床应用，（iii）通过注意力调制达到的生理状态代表了神经精神障碍中经常报道的电生理学发现的另一种解释，例如异常抑制。
