Center for Mind/ Brain Sciences, University of Trento, Italy; Department of Psychology, University of Salzburg, Austria; Center for Cognitive Neuroscience, University of Salzburg, Austria.
Center for Mind/ Brain Sciences, University of Trento, Italy; Department of Psychology, Royal Holloway University of London, United Kingdom.
Cortex. 2018 Jun;103:266-276. doi: 10.1016/j.cortex.2018.03.016. Epub 2018 Mar 27.
When we observe other people's actions, a number of parietal and precentral regions known to be involved in the planning and execution of actions are recruited for example seen as power decreases in alpha and beta frequencies indicative of increased activation. It has been argued that this recruitment reflects the process of simulating the observed action, thereby providing access to the meaning of the action. Alternatively, it has been suggested that rather than providing access to the meaning of an action, parietal and precentral regions might be recruited as a consequence of action understanding. A way to distinguish between these alternatives is to examine where in the brain and at which time point it is possible to discriminate between different types of actions (e.g., pointing or grasping) irrespective of the way these are performed. To this aim, we presented participants with videos of simple hand actions performed with the left or right hand towards a target on the left or the right side while recording magnetoencephalography (MEG) data. In each trial, participants were presented with two subsequent videos (S1, S2) depicting either the same (repeat trials) or different (non-repeat trials) actions. We predicted that areas that are sensitive to the type of action should show stronger adaptation (i.e., a smaller decrease in alpha and beta power) in repeat in comparison to non-repeat trials. Indeed, we observed less alpha and beta power decreases during the presentation of S2 when the action was repeated compared to when two different actions were presented indicating adaptation of neuronal populations that are selective for the type of action. Sources were obtained exclusively in posterior occipitotemporal regions, supporting the notion that an early differentiation of actions occurs outside the motor system.
当我们观察他人的行为时，一些已知参与动作规划和执行的顶叶和中央前区会被招募，例如，观察到阿尔法和贝塔频率的功率下降，表明激活增加。有人认为这种招募反映了模拟观察到的动作的过程，从而提供了对动作意义的理解。或者，有人认为，顶叶和中央前区的招募不是为了提供对动作意义的理解，而是作为对动作理解的结果。区分这两种可能性的一种方法是检查大脑中的哪个位置以及在哪个时间点可以区分不同类型的动作（例如，指向或抓取），而不管这些动作是如何执行的。为此，我们向参与者展示了简单的手部动作视频，这些动作是用左手或右手向左侧或右侧的目标进行的，同时记录了脑磁图（MEG）数据。在每个试验中，参与者都观看了两个后续视频（S1、S2），其中描绘了相同（重复试验）或不同（非重复试验）的动作。我们预测，对动作类型敏感的区域在重复试验中应比非重复试验中表现出更强的适应（即阿尔法和贝塔功率下降较小）。实际上，当动作重复时，与呈现两个不同动作时相比，在呈现 S2 时观察到的阿尔法和贝塔功率下降较小，这表明对动作类型具有选择性的神经元群体的适应。来源仅在后部枕颞区获得，支持了在运动系统之外早期区分动作的观点。
