School of Psychology, University of Surrey, UK.
Department of Psychology, University of York, UK.
Neuropsychologia. 2017 Sep;104:113-125. doi: 10.1016/j.neuropsychologia.2017.08.013. Epub 2017 Aug 11.
Recent work has suggested a potential link between the neurocognitive mechanisms supporting the retrieval of events and thematic associations (i.e., knowledge about how concepts relate in a meaningful context) and semantic control processes that support the capacity to shape retrieval to suit the circumstances. Thematic associations and events are inherently flexible: the meaning of an item changes depending on the context (for example, lamp goes with reading, bicycle and police). Control processes might stabilise weak yet currently-relevant interpretations during event understanding. In contrast, semantic retrieval for objects (to understand what items are, and the categories they belong to) is potentially constrained by sensory-motor features (e.g., bright light) that change less across contexts. Semantic control and event understanding produce overlapping patterns of activation in healthy participants in left prefrontal and temporoparietal regions, but the potential causal link between these aspects of semantic cognition has not been examined. We predict that event understanding relies on semantic control, due to associations being necessarily context-dependent and variable. We tested this hypothesis in two ways: (i) by examining thematic associations and object identity in patients with semantic aphasia, who have well-documented deficits of semantic control following left frontoparietal stroke and (ii) using the same tasks in healthy controls under dual-task conditions that depleted the capacity for cognitive control. The patients were impaired on both identity and thematic matching tasks, and they showed particular difficulty on non-dominant thematic associations which required greater control over semantic retrieval. Healthy participants showed the same pattern under conditions of divided attention. These findings support the view that semantic control is necessary for organising and constraining the retrieval of thematic associations.
最近的研究表明，支持事件和主题联想（即关于概念在有意义的上下文中如何关联的知识）检索的神经认知机制与支持根据情况塑造检索以适应环境的语义控制过程之间可能存在潜在联系。主题联想和事件本质上是灵活的：一个项目的含义取决于上下文（例如，灯与阅读、自行车和警察有关）。控制过程可能会在事件理解过程中稳定当前相关但较弱的解释。相比之下，对于物体的语义检索（理解物品是什么以及它们所属的类别）可能受到感觉运动特征（例如，亮光）的限制，这些特征在不同的上下文中变化较小。语义控制和事件理解在健康参与者的左前额叶和颞顶叶区域产生重叠的激活模式，但这些语义认知方面之间的潜在因果联系尚未得到检验。我们预测，由于联想必然依赖于上下文且具有变异性，因此事件理解依赖于语义控制。我们通过两种方式检验了这一假设：（i）通过检查语义性失语症患者的主题联想和物体身份，他们在左额顶叶中风后存在明显的语义控制缺陷；（ii）在健康对照组中使用相同的任务进行双任务条件测试，这会消耗认知控制能力。患者在身份和主题匹配任务上都存在障碍，并且他们在需要对语义检索进行更多控制的非主导主题联想上表现出特别的困难。健康参与者在注意力分散的情况下也表现出相同的模式。这些发现支持了这样一种观点，即语义控制对于组织和限制主题联想的检索是必要的。
