探討環境參照系與自我參照系於空間巡航中腦波反應之差異

Abstract

空間巡行(spatial navigation)的策略，可依照參照系(reference frame)的不同，分成自我(egocentric)和環境(allocentric)兩種空間表示方式。本研究以腦電波(EEG)探討汽車駕駛中，此兩種參照系於空間巡航中腦波反應之差異。本實驗利用虛擬實境(Virtual Reality)技術，建構3D虛擬場景，模擬真實的駕車環境。在實驗中以隧道為場景，以減少不必要的視覺刺激，探討此兩種參照系對空間描述的差異，藉此有效區分使用不同思考策略的受測者並進一步找出其腦波反映上的差異。在資料分析上，我們利用獨立成分分析(ICA)，將測量到的腦電波，分離成互相獨立的大腦訊號源，並以事件相關頻譜擾動(ERSP)之分析法，觀察自我參照系與環境參照系之間腦波頻率在時間上變化的差異。實驗結果發現，在自我參照系和環境參照系受測者之腦電波有顯著的差異。自我參照系的受測者，其大腦頂葉區(Parietal)在，在空間巡航時，有較強烈的反應。而環境參照系的受測者則是在枕葉區(Occipital)，在腦部重組巡行空間時，有較強烈的反應。除此之外，自我參照系的受測者，其大腦頂葉區(Parietal)在，在空間巡航時，其alpha波的能量強弱與其衡量空間巡行角度的正確性有高度的相關。此實驗結果幫助我們了解與空間巡行感知相關的腦神經網路，此一結果將有助於進一步探討不同策略受試者其空間迷向時的腦波變化，並能藉此發展出一套輔助裝置，協助受試者增進空間巡行時的能力，減少其發生空間迷向的機會。

The aim of this study was to investigate the differences of brain dynamics between the use of allocentric reference frames and egocentric reference frames during spatial navigation. A tunnel task was designed to classify subjects into allocentric or egocentric spatial representation users. Despite of the differences of mental spatial representation, behavioral performance in general were compatible between the two strategies subjects in the tunnel task. Task-related EEG dynamics in both tonic and phasic power changes were analyzed using independent component analysis (ICA), time-frequency and non-parametric static test. Results supported the dissociation brain activities between the uses of allocentric and egocentric reference frames. Both tonic and phasic power changes were significantly different between the navigation strategy groups. Subjects who preferred to use the allocentric spatial representation showed stronger activation in occipital area during path integration whereas subjects using the egocentric reference frames showed stronger activation in parietal area during path integration. The distinct brain regions involved in the navigation process suggested that encodings of allocentric and egocentric reference frames were via the ventral and dorsal neural network respectively.