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正常人之視覺空間注意力事件誘發電位

Event-Related Potentials of Visual Spatial Attention in Healthy Subjects

摘要


視覺注意力受外界刺激之空間及時間因素影響。本實驗藉由事件誘發電位(event-related potentials, ERPs)的研究,以了解正常人執行視覺空間注意力之潛在腦部機轉。 本實驗收集17位健康成人,平均年齡爲23.3歲。由Neurostim系統產生視覺刺激訊號,在3種不同的條件組合下提供8種刺激:提示(cue)的正確與否;刺激延遲(delay)的時間(100 msec或800 msec);刺激的方向(左側或右側)。資料處理後進行ERPs的波幅及波峰時間的分析。統計方法採重複量數變異數分析(repeated measures ANOVA),比較不同條件下的ERPs,定義P值<0.05爲統計學上顯著意義。同時也記錄大腦等位圖(brain mapping)。 本研究發現,在執行空間注意力測試時主要觀察到三個不同的波形,Nl(波峰時間約爲170~180 ms,波幅約爲-2~-4µV)、P2(波峰時間約爲250~260 ms,波幅約爲4~6µV)及P3(波峰時間約爲370~380ms,波幅約爲3~4µV)。Nl波於目標物對側枕葉、頂葉波幅最明顯。P2波於目標物對側之枕葉、頂葉、額葉中央及頭頂中央波幅較明顯。P3波於額葉及頭頂中央波幅最明顯。Nl與P2波皆是逢錯誤提示而在腦部視野對側波幅變大,但P3波在正確提示時波幅較大。 本研究顯示,錯誤提示刺激可引起較大的視覺注意,而造成對側枕葉及頂葉之皮質活性增加;而正確提示刺激可引起較大的認知處理,但會受處理過程的負波影響。

並列摘要


Visual attention can be manipulated by temporal and spatial factors of stimuli. The purpose of this study is to investigate the underlying mechanism of visual spatial attention of healthy subjects through event-related potential (ERP) study. The subjects of the study were 17 healthy adults, mean age 23.3 years. The visual stimuli were generated by the Neurostim system and presented in groups of eight under three different conditions: cueing (valid, invalid), delay (100 ms, 800 ms) and visual field sides (right and left). ERPs were recorded by 10 Neuroscan systems electrodes placed on each subject's scalp. The latencies and amplitudes of ERPs were then analyzed. Repeated measures ANOVA was used to compare ERPs resulting from different conditions. The difference in measurements was considered significant if P <0.05. Brain mapping was obtained to recognize the ERP topography in each condition. Three different ERPs, Nl (170-180ms, -2~-4µV), P2(250-260 ms, 4-6µV), and P3 (370-380 ms, 3-4µV), were elicited during the visual spatial attention task. Ni wave distribution was higher in contralateral occipital and parietal lobes. P2 wave distribution was higher in contralateral occipital and parietal lobes, frontal lobes, and central areas. P3 wave distribution was higher in frontal lobes and central brain areas. Ni and P2 amplitudes were greater during contralateral invalid-cue stimuli presentations, however, P3 amplitudes were greater during contralateral valid-cue stimuli presentation. Our findings suggest that invalid-cue stimuli may elicit greater attention, resulting in higher cortical activity in contralateral occipital and parietal lobes. The valid-cue stimuli may induce a higher cognitive processing produced by ”processing negativity.”

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