比較空間與社交導航在距離處理之神經機制

Abstract

在空間環境和社交網絡中找尋出路，被認為涉及類似的心理表徵。我們認為這種心理層面上的重疊與距離的表示形式（即空間和社交距離）差異有關，並試圖找出支持這種觀點的神經證據。本研究招募20位年輕受試者進行功能性磁振造影實驗，受試者將在一個虛擬環境中學習並記憶12個空間目標的相對位置。之後受試者也在同樣的虛擬環境中學習12個代理人的社交網絡。提取任務探討受試者對於地標之間的空間距離或代理人之間的社交距離之判斷。行為結果發現隨著需要判斷之距離增加，空間和社交距離判斷顯示出類似的高估或低估距離，所花費的判斷時間也會增加。腦影像結果顯示，在進行空間距離和社交距離判斷時都涉及了多個大腦區域。然而，僅在楔前葉中發現了共同由距離調節的最小支持之腦反應，隨著距離的增加，其表現出更高的反應，這在空間或社交距離判斷之間沒有區別。儘管處在相同的視覺空間環境刺激，但空間客觀距離的參數變化調節了視覺區域的反應，而社交客觀距離則調節了左額葉和右頂葉的反應。有趣的是，當受試者在空間和社交導航中抵達導航目標時，發現左側海馬迴的反應。我們認為在腦中對於空間和社交有共同的距離表現之觀點需要更進一步的研究。

Finding one’s way around spatial environments and social networks has been suggested to involve similar psychological representations. We considered that this psychological overlap, if any, must relate to differences in distance representations (i.e., spatial and social distances) and sought to uncover neural evidence supporting this view. 20 young adults underwent a functional magnetic resonance imaging (fMRI) experiment in which participants learned the relative locations of 12 spatial targets in a virtual environment. Participants also learned the social network of 12 agents located in the same virtual environment. Retrieval tasks then either probed participants about spatial distances between landmarks or social distances between agents. Spatial and social distance judgements evinced similar over- to under-estimation as distances increased, as well as incremental time spent. Several brain areas were engaged during both spatial and social distance judgments. However, minimal support for a common brain response that was modulated by distance was found only in the precuneus, which showed higher activity with increasing distance that did not differ between spatial or social judgments. Instead, despite stimuli based on the same visuospatial environment, parametric variations in spatial objective distances modulated visual area responses whereas social objective distances modulated left frontal and right parietal responses. Interestingly, the left hippocampus was activated when participants reached navigational goals in both spatial and social navigation. We suggest that the view of a common distance representation for spatial and social nodes in the brain requires further investigation.