Kolasinski James, Dima Diana C, Mehler David M A, Stephenson Alice, Valadan Sara, Kusmia Slawomir, Rossiter Holly E
Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, CF24 4HQ, UK.
Cereb Cortex Commun. 2020;1(1):tgaa009. doi: 10.1093/texcom/tgaa009. Epub 2020 Apr 4.
The organizing principle of human motor cortex does not follow an anatomical body map, but rather a distributed representational structure in which motor primitives are combined to produce motor outputs. Electrophysiological recordings in primates and human imaging data suggest that M1 encodes kinematic features of movements, such as joint position and velocity. However, M1 exhibits well-documented sensory responses to cutaneous and proprioceptive stimuli, raising questions regarding the origins of kinematic motor representations: are they relevant in top-down motor control, or are they an epiphenomenon of bottom-up sensory feedback during movement? Here we provide evidence for spatially and temporally distinct encoding of kinematic and muscle information in human M1 during the production of a wide variety of naturalistic hand movements. Using a powerful combination of high-field functional magnetic resonance imaging and magnetoencephalography, a spatial and temporal multivariate representational similarity analysis revealed encoding of kinematic information in more caudal regions of M1, over 200 ms before movement onset. In contrast, patterns of muscle activity were encoded in more rostral motor regions much later after movements began. We provide compelling evidence that top-down control of dexterous movement engages kinematic representations in caudal regions of M1 prior to movement production.
人类运动皮层的组织原则并非遵循解剖学身体图谱，而是一种分布式表征结构，其中运动原语被组合起来以产生运动输出。对灵长类动物的电生理记录和人类成像数据表明，初级运动皮层（M1）编码运动的运动学特征，如关节位置和速度。然而，M1对皮肤和本体感觉刺激表现出有充分记录的感觉反应，这就引发了关于运动学运动表征起源的问题：它们在自上而下的运动控制中是否相关，还是它们是运动过程中自下而上感觉反馈的一种附带现象？在这里，我们提供证据表明，在产生各种自然手部运动期间，人类M1中运动学和肌肉信息在空间和时间上存在不同的编码。使用高场功能磁共振成像和脑磁图的强大组合，一种空间和时间多变量表征相似性分析揭示，在运动开始前200多毫秒，运动学信息在M1的更靠尾侧区域被编码。相比之下，肌肉活动模式在运动开始后很久才在更靠头侧的运动区域被编码。我们提供了令人信服的证据，表明在产生运动之前，对灵巧运动的自上而下控制会激活M1尾侧区域的运动学表征。
