虛擬實境靜態與動態驅動平台刺激下探討腦波與空間巡航表現之關係

Abstract

現今衛星導航系統(GPS)已成為人類生活中不可或缺的最大幫手，但過度倚賴衛星導航，人腦有可能逐漸退化，人類天生的方向感以及對環境的認知能力也可能會出現明顯退化。過去研究發現，於空間探索時，依照參考座標系(reference frame)的不同，可分成環境(allocentric)與自我(egocentric)兩種空間表示方式。在神經造影(neuroimaging)與功能性磁振造影(fMRI)的研究結果中也已經證實，當進行不同的空間探索策略時，會活化不同的腦部區域；另外，過去的研究大多數都是在靜態環境下所完成，但在現實生活中，進行空間巡航時都是處於動態刺激的環境下。本研究以腦電波(EEG)探討汽車駕駛中，空間巡航(spatial navigation)之認知反應以及方向感，主要重點為: (1)於相同實驗設計下提供靜態與動態兩種刺激，探討腦波變化與空間巡航的行為表現之差異；(2)探討腦波變化與空間巡航表現之關係。本實驗中，利用虛擬實境(Virtual Reality)技術，建構360□環繞式虛擬場景，利用視覺流動(visual-flow)提供靜態刺激，並利用油壓六軸平台提供動態刺激，模擬出更加真實的駕車環境。實驗設計，利用隧道場景來探討空間探索問題，在受測者沒有接受任何提示下，可有效區分出使用不同思考策略(allocentric和eoocentric)的受測者。共有十二位受測者參與此實驗。實驗過程中，以64個電極的腦波帽來量測與收集腦波訊號。 利用獨立成分分析(ICA)方法，將腦電波分離出互相獨立的訊號源，並透過事件相關頻譜擾動(ERSP)觀察腦波在頻率和時間上的變化，並以分群方式(Clustering)探討分析結果的穩定性與一致性。結果顯示，在動態刺激下，觀察到parietal腦區中，α頻帶(10-12Hz)能量增加與受測者回答角度的誤差值之間統計顯示出高度負相關(CC = - 0.9433; p-value < 0.01)。未來可針對parietal腦區的α頻帶(10-12Hz)能量增加之多寡，當作是空間巡航時方向感表現好壞的參考指標。

Nowadays, the Global Positioning System (GPS) has become an indispensable part for using in human life, which helps to plan the route during the navigations. However, human innate sense of orientation and the spatial ability would be apparent in degradation, thereby brain region would gradually loss of spatial processing functions if they overuse the GPS. Previous studies had observed that two different strategy groups were identified, using an allocentric and egocentric reference frame, during spatial exploration. Neuroimaging by fMRI technique had demonstrated the brain activations were different between the use of an allocentric and egocentric reference frames. A part of the previous studies was experimented in a static environment, but subjects were navigating in the dynamic stimulus environments in real life. Understanding the brain activations in real life applications are still needed furthermore improved. Therefore, in this study, we have aim to investigate the subject’s cognitive state and their dynamics changes during the spatial navigations. The goals of this study: (1) Investigate the brain dynamics and behavioral performance during navigation in static (motionless) and dynamic (motion) stimulus under the same experiment scene conditions, (2) Correlate with the brain dynamics and the behavioral performance. The experiment was constructed a virtual surrounding scene of 360□ by virtual-reality technology which provided the static stimulus via visual-flow and dynamic stimulus by hydraulic six-axis platform to simulate a more realistic driving environment. For identifying the different strategy groups, it was ease to distinct between the allocerntric and egocentric of subject by using the tunnel scene. There were twelve subjects participated in the experiment and the EEG signals were measured by the standard 64-channel EEG hat. The EEG data were then separated into independent signals by independent component analysis (ICA) decomposition and the use of the event-related disturbance spectrum (ERSP) in the EEG signals changes of frequency domain. Results showed that the correlation between the power increase in alpha band and error homing angle was negative (CC = - 0.9433; p-value < 0.01) in the dynamic stimulus. The power increase of alpha band in parietal region could refer as a basis to score the quality of the brain activations performing in spatial behavioral performance in the future. To summarize, this method proposed in this study complements other existing human brain imaging approaches for the investigation of the coupling between brain activations and sensing the orientation.