Table_1_Electrophysiological correlates of distance and direction processing during cognitive map retrieval: A source analysis.pdf

IntroductionThe cognitive map is an internal representation of the environment and allows us to navigate through familiar environments. It preserves the distances and directions between landmarks which help us orient ourselves in our surroundings. The aim of our task was to understand the role played by theta waves in the cognitive map and especially how the cognitive map is recalled and how the manipulation of distances and directions occurs within the cognitive map.
MethodIn order to investigate the neural correlates of the cognitive map, we used the Cognitive Map Recall Test, in which 33 participants had to estimate distances and directions between familiar landmarks tailored to their own knowledge. We examined the role of theta waves in the cognitive map, as well as the brain regions that generated them. To that aim, we performed electroencephalographic source imaging while focusing on frequency spectral analysis.
ResultsWe observed increases of theta amplitude in the frontal, temporal, parahippocampal gyri and temporal poles during the recall of the cognitive map. We also found increases of theta amplitude in the temporal pole and retrosplenial cortex during manipulation of directions. Overall, direction processing induces higher theta amplitude than distance processing, especially in the temporal lobe, and higher theta amplitude during recall compared to manipulation, except in the retrosplenial cortex where this pattern was reversed.
DiscussionWe reveal the role of theta waves as a marker of directional processing in the retrosplenial cortex and the temporal poles during the manipulation of spatial information. Increases in theta waves in frontal, parahippocampal, temporal and temporal pole regions appear to be markers of working memory and cognitive map recall. Therefore, our Cognitive Map Recall Test could be useful for testing directional difficulties in patients. Our work also shows that there are two distinct parts to the cognitive map test: recall and manipulation of spatial information. This is often considered as two similar processes in the literature, but our work demonstrates that these processes could be different, with theta waves from different brain regions contributing to either recall or manipulation; this should be considered in future studies.

引言
认知地图（Cognitive Map）是个体对所处环境的内部表征，可帮助我们在熟悉场景中完成导航。该表征保留了地标间的距离与方位信息，辅助我们在周遭环境中实现自我定位。本研究的核心目标为解析θ波（theta wave）在认知地图中的作用机制，特别是认知地图的提取过程，以及距离与方位的操纵如何在认知地图内部发生。

方法
为探究认知地图的神经相关指标，本研究采用了认知地图提取测试（Cognitive Map Recall Test）：33名参与者需要估算适配自身认知的熟悉地标之间的距离与方位。我们同时考察了θ波在认知地图中的作用，以及产生θ波的脑区。为此，我们开展了脑电图源成像实验，并重点聚焦频谱分析环节。

结果
在认知地图提取阶段，我们观测到额叶、颞叶、海马旁回以及颞极区域的θ波振幅显著提升。在方位操纵阶段，颞极与压后皮层的θ波振幅同样出现升高。整体而言，方位加工过程的θ波振幅高于距离加工，尤其在颞叶区域；且相较于操纵阶段，提取阶段的θ波振幅更高，但压后皮层的这一模式恰好相反。

讨论
本研究揭示了空间信息操纵阶段，θ波可作为压后皮层与颞极区域方位加工的标记物。额叶、海马旁回、颞叶以及颞极区域的θ波振幅升高，可作为工作记忆与认知地图提取的标记指标。因此，本研究采用的认知地图提取测试可用于检测患者的方位认知障碍。此外，本研究表明认知地图测试包含两个截然不同的过程：空间信息的提取与操纵。现有文献通常将这两个过程视为相似环节，但本研究证实二者存在差异——不同脑区产生的θ波分别参与提取或操纵过程，这一结论需在后续研究中予以重视。