大白鼠薄索核內尾部代表區域之電生理及解剖研究

Abstract

本實驗以電生理及解剖的方法探討大鼠薄索核中尾部的代表區域。對大鼠尾巴不同部位施以電刺激所引起薄索核中的場電位反應形式幾乎都重疊。單一神經元記錄也顯示了相似的結果，也就是說，尾巴不同區域的代表神經元在薄索核之中的分佈區域也是重疊的。第三種使用的方法是山葵過氧化氫酵素正向追蹤。自尾部至薄索核的傳入神經利用WGA-HRP和CTB-HRP來追蹤。沿著身體中間一側面方向的軸上，從尾巴不同區域注射後染到的神經末梢在薄索核中是有組織的結構。尾巴尖端的輸入神經投射到薄索核中最接近身體中線的地方，而尾巴基部則投射到較為靠身體外側的地方。在吻端－尾端和背側－腹側的方向，自尾巴尖端、中段、基部傳入的神經纖維末梢在薄索核之中分佈在重疊的區域。總結以上，只有神經纖維正向追蹤方法在薄索核中找到沿著中間－側面方向的結構。而無論是誘發場電位或單一神經元記錄的方法在薄索核中均未辨別出一致的尾部代表形態。

This study used electrophysiological and anatomical methods to evaluate the tail representation area in the gracile nucleus of rats. Electrical stimulation of different parts of the rat tail evoked mostly overlapping field potential patterns in the gracile nucleus. Similar results were revealed with single-unit recording method, i.e., the representative neurons of different tail regions were found to be distributed in overlapping areas in the gracile nucleus. The third method used was horseradish peroxidase (HRP) anterograde tracing. Afferent inputs from tail to gracile nucleus were traced by WGA-HRP and CTB-HRP. Labeled terminals from different regions of the tail were organized along the medial-lateral axis of the body. Tail tip inputs projected to the most median border of the gracile nucleus, and tail base inputs projected to more lateral parts. Along the rostral-caudal and dorsal-ventral axes, labeled terminals from tailtip, midtail, and tailbase were found to be distributed in overlapping areas. In conclusion, only medial-lateral somatotopic organization were found in the gracile nucleus with anterograde fiber tracing method. No consistent representation pattern could be discerned in the gracile nucleus with either evoked field potential or single-unit recording methods.