動態亂點立體圖之視誘發電位

Visual Evoked Potential of Random-Dot Stereopsis

王藹侯(Ai-Hou Wang)

《中華民國眼科醫學會雜誌》 33卷1期 (1994/03) Pp. 54-59

https://doi.org/10.30048/ACTASOS.199403.0009

摘要

我們以動態亂點立體圖為視刺激器，記錄和亂點立體感相關的視誘發電位。立體圖僅包含一垂直綠或水平緣，將視角18.2×18.2度的方形分為兩個31.6分角立體感的半平面，以2.92Hz的速度上、下反轉，單眼所見則以每秒鐘70張的速度更替亂點立體圖。記錄20秒鐘腦波中，共包含深度覺58週期和單眼1392張立體圖。以兩種方法抽取視誘發電位：(1)以離散傅立葉分析抽取深度覺第一諧波和第二諧波上之視誘發電位；(2)以快速傅立葉分析列出輻度的頻譜。立體感相關的視誘發電位主要集中於深度覺的第二諧波。我們測試三位立體感正常者和兩位無立體感者，前者在第二諧波上有視誘發電位，後者則無。以兩種方法抽取視誘發電位，互相參考比對，我們成功地抽取到和亂點立體感相關的視誘發電位。

並列摘要

Applying dynamic random-dot stereogram (RDS) as visual stimulator, we recorded random-dot-stereopsis-related visual evoked potential (VEP). The simplest 'figure-containing' RDS had a single vertical or horizontal edge hidden in. This single edge separated the stereogram, 18.2×18.2 degrees at 50 cm distance, into two half-planes with peak-to-peak stereopsis of 31.6 min-arc. The anaglyphical RDS was changed every screen frame, ie. 70 frames per second. The depth of half-planes was reversed at 2.92 Hz. We collected 20 seconds of EEG which contained 58 depth cycles and 1392 monocular presentations. VEP was extracted with two methods: (1) discrete Fourier analysis of the first and second harmonics of depth cycle; (2) Fast Fourier transformation to get the amplitude spectrum. Stereopsis-related VEP from this special dynamic RDS concentrated its energy at second harmonic of depth cycle. We tested three stereopsis normals and two stereoblinds. The former had VEP at this frequency while the latter did not have.

並列關鍵字

Stereopsis ； Dynamic Random-dot Stereogram ； Visual Evoked Potential