人腦在觀看高與低社交程度影片時的電生理反應

Abstract

本研究使用腦電圖(electroencephalography, EEG)研究人腦在自然狀況下如何處理社交相關的訊息。我們招募了17位健康受試者來觀看六部影片。影片分為三個場景下具有高社交或低社交互動。在觀看影片的同時，我們收取腦電圖訊號。訊號經由訊號源定位後，將神經活動分成theta、alpha、beta和gamma頻段的震盪。之後我們進行兩種分析。其一是比較神經活動震盪強度在觀看高和低社交影片的差異。其二是個體間相關性(inter-subject correlation, ISC) 在觀看高和低社交影片的差異。 結果顯示在觀看高低社交影片中，人腦振盪強度上各頻段都沒有顯著差異。而在ISC結果上，在低頻帶 (theta, alpha)上布洛卡氏區(Broca’s area)的同步性在觀看高社交影片比在觀看低社交影片來得高。而在高頻帶 (beta, gamma)上下顳葉(inferior temporal lobe)，顳中回(middle temporal lobe) 的同步性在觀看高社交影片比在觀看低社交影片來得高。整體來說，神經震盪強度差異小的地方可能會有明顯的同步程度差異。這說明單看神經震盪強度大小可能會忽略人在認知過程中其實有相似腦波振盪變化過程。因此我們認為同時探討腦內皮質訊號源上的振盪強度和同步程度，有助於更精確瞭解人腦反應在處理自然複雜刺激下的認知過程。

This research used electroencephalography (EEG) to study how human brain process social-related information in natural situation. Seventeen healthy participants were asked to watch six movies. The movies are divided into high and low sociality in each of three different scenes. EEG signal was recorded when participants watch movies. After estimating source location from EEG signal, the spectral powers of theta, alpha, beta, and gamma bands were estimated at each source location. Afterward, we compared intensity of oscillation during watching movies with high and low social interaction by average spectral power. We also compared the degree of synchronization in the process order of oscillation during watching high and low sociality movies among subjects by inter-subject correlation (ISC) coefficient. The results showed that the oscillation intensities were not significantly different at any frequency band between EEG sources of watching movies of high and of low sociality. On the other hand, there was higher EEG source synchronization during watching high sociality than low sociality movies at low frequency band (theta, alpha) in Broca’s area. This contrast in synchronization was also shown at high frequency band (beta, gamma) in inferior and middle temporal lobe. Our result demonstrated a case of oscillatory response that has low oscillation in intensity but has highly synchronized process order among people in natural situation. This indicate that social cognition might induce the low intensity but high synchronization of oscillation. Therefore, we believe that in addition to analyzing the power of oscillations, analyzing ISC of oscillations in the cortical source can provide more information of the cognitive processes evoked by complicated natural stimuli.