实地导航训练提高大脑功能连接模式稳定性

Real-world navigation training enhances the stability of large-scale brain connectivity patterns

空间导航主要依赖于两种空间表征:自我中心参照表征与环境中心参照表征。然而,个体在现实环境中的空间导航能力提升与这两种空间表征存在何种关联仍未可知。为此,本研究结合行为测量与功能核磁共振技术(fMRI),对非熟悉环境实地空间导航训练前后个体空间导航能力和大脑全局性功能连接模式的改变进行分析,系统考察个体实地空间导航能力提高的内在神经机制。研究结果发现,训练组被试在训练后进行空间导航任务时,自我中心参照表征的核心脑区——顶上小叶(SPL)的神经活动显著增强。更为重要地,训练显著提高了以SPL为核心的全脑功能连接模式的稳定性,且与个体导航任务表现的提高呈正相关。上述结果表明,实地空间导航能力的提高与自我中心参照表征的增强存在密切关联,并进一步表现为SPL与全脑其他区域的信息交互通路的固化。

Spatial navigation involves both egocentric(body-centered)and allocentric(environment-centered)spatial representations,which are hosted in structurally and functionally segregated brain regions.The two types of representations are flexibly weighted in response to changing environmental cues and landmarks during the navigational process,thereby achieving a stable and robust neural code of the target location.However,it remains unknown whether and how improvements in real-world navigational proficiency are related to these two types of spatial representations.In the present study,participants who were unfamiliar with the campus layout(newly arrived university freshmen)received a real-world navigation training for 20 days.Before and after the training,participants received fMRI scanning when they performed a distance judgment task and a paper folding task(as a control).In addition,they were comprehensively tested for their navigational ability via several behavioral tasks(live pointing,offsite direction estimation and offsite distance estimation)outside the scanner.A control group comprised participants who underwent the same fMRI scanning and behavioral tests but did not receive any training.By comparing the training-induced changes in regional activation and task-based global functional connectivity(FC)patterns between the two groups,we investigated the neural correlates of the improvement in real-world navigation performance.We found that the real-world navigation training improved participants'performance during all the behavioral tasks.At the neural level,we observed significant training-induced activation enhancement in the right superior parietal lobule(rSPL),a core brain region that hosts egocentric representation.Moreover,the training increased the global FC pattern stability with the rSPL as the seed region during the distance judgment task,although it had no significant effects on the FC pattern stability during the baseline task.Finally,the increase in global FC pattern stability also predicted individual’s improvement in behavioral performance during the distance judgment task.Notably,these effects were found only in the trained group;no similar effects were observed in the control group.These findings indicated that improvement in real-word navigation ability was associated with enhanced egocentric representation.Moreover,the navigation training consolidated the information exchange routes among brain regions,thereby enhancing the precision of cognitive map retrieval.In summary,our study highlights the importance of egocentric representation enhancement in rSPL in improving real-world navigation ability in unfamiliar environments.Furthermore,navigation training facilitates spatial information retrieval by reinforcing the information exchange pathways between the rSPL and other brain areas.