PDF(Pubmed)
Abstract：
The intention to act influences the computations of various task-relevant features. However, little is known about the time course of these computations. Furthermore, it is commonly held that these computations are governed by conjunctive neural representations of the features. But, support for this view comes from paradigms arbitrarily combining task features and affordances, thus requiring representations in working memory. Therefore, the present study used electroencephalography and a well-rehearsed task with features that afford minimal working memory representations to investigate the temporal evolution of feature representations and their potential integration in the brain. Female and male human participants grasped objects or touched them with a knuckle. Objects had different shapes and were made of heavy or light materials with shape and weight being relevant for grasping, not for \"knuckling.\" Using multivariate analysis showed that representations of object shape were similar for grasping and knuckling. However, only for grasping did early shape representations reactivate at later phases of grasp planning, suggesting that sensorimotor control signals feed back to the early visual cortex. Grasp-specific representations of material/weight only arose during grasp execution after object contact during the load phase. A trend for integrated representations of shape and material also became grasp-specific but only briefly during the movement onset. These results suggest that the brain generates action-specific representations of relevant features as required for the different subcomponents of its action computations. Our results argue against the view that goal-directed actions inevitably join all features of a task into a sustained and unified neural representation.
摘要：
行为意图影响各种任务相关特征的计算。然而,对这些计算的时间过程知之甚少。此外，通常认为，这些计算由特征的联合神经表示控制。但是,对这一观点的支持来自任意组合任务特征和负担能力的范式，因此，需要在工作记忆中表示。因此,本研究使用脑电图和一项经过精心演练的任务，其特征可提供最少的工作记忆表征，以研究特征表征的时间演变及其在大脑中的潜在整合。女性和男性参与者观看并抓住物体或用指关节触摸它们。物体有不同的形状，由重或轻的材料制成，形状和重量与抓握有关，不是为了“指关节”。“使用多变量分析表明，物体形状的表示对于抓握和指关节是相似的。然而,只有在抓取计划的后期阶段，早期的形状表示才会重新激活，这表明感觉运动控制信号反馈到早期视觉皮层。材料/重量的抓取特定表示仅在加载阶段的物体接触后的抓取执行过程中出现。形状和材料的综合表示的趋势也变得特定于抓握，但在运动开始时才短暂。这些结果表明，大脑根据其动作计算的不同子组件的要求，生成相关特征的特定动作表示。我们的结果反对这样的观点，即目标导向的行动不可避免地将任务的所有特征加入到持续和统一的神经表示中。重要性陈述将任务的所有特征集成到联合表示或事件文件中的想法得到广泛支持，但重要的是基于具有任意刺激-响应组合的范例。我们的研究是第一个研究使用脑电图在这种日常生活任务中使用过度学习的刺激-反应映射来搜索特征整合的神经基础的研究。与事件文件的概念相反，我们发现集成表示的证据有限。相反，我们发现，与任务相关的特征在行动的特定阶段形成了表征，建议行动意图重新激活相关特征的表示。我们的结果表明，对于任何类型的目标导向行为，集成表示都不会普遍出现，而是以按需计算的方式出现。
