使用虛擬實境系統誘發事件相關電位P300之研究

A 3-D Virtual Reality Based Sensory Oddball Task for Eliciting P300

李開群(Kai-Chiun Li)

指導教授 ： 陳純娟

國立中央大學/工學院/生物醫學工程研究所/碩士(2012年)

摘要

P300是由新異刺激程序誘發的事件相關電位，且它會受注意力影響。本研究的目的是使用3D虛擬實境技術建立一個能用來誘發體感覺P300的刺激程序。
本研究收錄了12位健康右撇子受試者，使用他們的慣用手在虛擬環境中進行接球實驗時之腦電波訊號。接球實驗有兩種刺激條件：標準刺激(有力回饋且經由力回饋系統傳遞)和靶刺激(無力回饋)，發生率分別為80%和20% (各為479和121次)。本研究共收集32頻道腦電波，取樣頻率為250 Hz，分段長度為-500到+2500毫秒，觀測可能出現P300之時間區段為+248到+800毫秒，濾波使用截止頻率為0.1和59 Hz的帶通濾波器。腦波訊號先經平均處理後，再利用時空模板的雙重評定標準獨立成分分析法去移除眼動訊號。
結果顯示，所有受試者在Pz (P<0.001)、P3 (P<0.001)和P4 (P<0.001)頻道都有誘發P300，其平均振幅與平均潛伏期(±標準差)分別為8.1±3.4、7.2±3.8和6.5±3.2μV和549±108、617±125和563±129毫秒，而獨立成分分析法可移除眼動訊號，降低對腦波訊號的干擾。
本研究證實3D虛擬實境系統可用來誘發體感覺P300，而獨立成分分析法可使腦波訊號訊雜比提高，這表示虛擬實境技術能被用來進行腦功能的研究。虛擬實境技術可提供一個容易控制的虛擬環境，在未來，本研究之設計及參數可進行體感覺P300的研究，也可作為中風後運動功能復健之臨床研究的參考。

關鍵字

3D虛擬實境 ； 腦電波圖 ； 體感覺P300

並列摘要

P300 is elicited in an oddball paradigm and associated with attention. In this study, we aim to establish a novel protocol using 3-D Virtual Reality technique to elicit the somatosensory P300 components.
Twelve healthy, right-handed subjects were instructed to perform a ball catch task using their dominant hand under a 3-D Virtual Reality scheme. The ball catch task has two conditions: standard (with force feedback) and target (without force feedback), with the 479 and 121 trials (i.e. 80% and 20% occurring rate), respectively. The feedback force in the standard condition was delivered to the subjects via a haptic feedback system. 32 channels electroencephalogram (EEG) were recorded with 250 Hz sampling rate during the task. The data were epoched from -500 to +2500 ms, and filtered with 0.1-59 Hz band-pass filter. The window of interest was set to be between +248 to +800 ms after ball catch. Independent Component Analysis (ICA) was employed to remove the electrooculogram (EOG) interference according to spatial and temporal criteria.
There is strong evidence suggesting that P300 components were elicited at Pz (p<0.001), P3 (P<0.001) and P4 (P<0.001) in all subjects. The mean peak amplitudes are 8.1±3.4, 7.2±3.8, and 6.5±3.2μV, and the mean peak latencies are 549±108, 617±125, and 563±129ms at Pz, P3 and P4, respectively. In addition, ICA could remove the EOG contamination effectively.
In conclusion, we have shown that 3-D Virtual Reality technique can be used to elicit the somatosensory P300 components reliably and Independent Component Analysis could increase the Signal-to-Noise Ratio of brain signals by removing the unwanted EOG components. It provides direct evidence that Virtual Reality technique is feasible for studying brain function. As VR technique can provide a simulated environment which is easy to manipulate and control, we believe that the outcome of this study could serve as a reference point of sensory P300 study and could most benefit the studies of motor recovery during rehabilitation after stroke in the future as in those studies, the control of task parameters is crucial.

並列關鍵字

3D VR ； EEG ； somatosensory P300

參考文獻

1. Sanei, S. and J. Chambers, EEG signal processing. 2007, Chichester, England ; Hoboken, NJ: John Wiley & Sons. p. 1-2.

2. Duncan, C.C., et al., Event-related potentials in clinical research: guidelines for eliciting, recording, and quantifying mismatch negativity, P300, and N400. Clin Neurophysiol, 2009. 120(11): p. 1883-908.

3. Polich, J., Updating P300: an integrative theory of P3a and P3b. Clin Neurophysiol, 2007. 118(10): p. 2128-48.

4. Verleger, R., P3b: towards some decision about memory. Clin Neurophysiol, 2008. 119(4): p. 968-70.

5. Kemner, C., et al., Auditory event-related brain potentials in autistic children and three different control groups. Biol Psychiatry, 1995. 38(3): p. 150-65.