猫小脑第Ⅶ小叶皮层-核团投射的电生理学研究

ELECTROPHYSIOLOGICAL STUDY OF THE CORTICONUCLEAR PROJECTION IN THE LOBULE VII OF CAT CEREBELLUM

在三碘季铵酚制动的去大脑猫上,记录了小脑后叶的第Ⅶ小叶皮层浦肯野细胞(PC)对分别刺激顶核、间位核和齿状核的逆行场电位和逆行单位反应,以确定小脑皮层PC对这三个核团投射的空间分布。在鉴定了PC对其靶核团的投射后,用特制的模拟自然屈腕运动的刺激装置来推动猫同侧前肢的掌背,造成腕关节一次轻微的屈曲,观察该PG对这一刺激的单位反应。实验资料用电子计算机处理,作出平均诱发电位和刺激后时间直方图。 本文以电生理学方法揭示,猫小脑后叶第Ⅶ小叶皮层-核团投射存在较明确的纵区分布模式,纵区之间的分界线走向有一定的弯曲,与前叶略有不同。小脑后叶皮层从中线到两侧2.8mm为顶核区(FZ);其外侧为间位核区(IZ),最大宽度约为3.5mm;齿状核区(DZ)约始于5.0mm处。这三个不同纵区的PC对外周自然屈腕刺激都有反应,但反应细胞的百分数不同,FZ有59％的PC对外周刺激有反应,IZ为84％,DZ为20％。这些结果表明后叶第Ⅶ小叶具有类似于前叶的功能分布,IZ的PC对外周刺激有更大的调制作用,提示该皮层-核团投射的纵区结构有其特定的功能意义。

Antidromic field potentials and antidromic unit responses of Purkinje cells (PCs) to the stimulation of fastig al nucleus (FN), interposed nucleus (IN) and dentate nucleus (DN) were respectively recorded from the lobule Ⅶ of posterior cortex of decerebrated cats, to identify the corticonuclear projection in the lobule Ⅶ. After antidromically identified, simple and complex spike responses of PCs to natural peripheral forepaw extension-flexion stimuli were observed. All data were analysed by a computer, and average field potentials and poststimulus time histograms (PSTHs) weie constructed. The results show that the corticonuclear zones are sharply demarcated on the lobule Ⅶ of posterior cortex. The boundary between the fastigial zone (FZ) and the interposed zone (IZ) on the lobule Ⅶ is not straight, but bends. Among sublobule ⅦAa-ⅦAd the FZ-IZ boundary bends from 2.8 m n to 1.5mm laterally to the midline. The boundary between IZ and dentata zone (DZ) was about 5.0 mm away from the midline. The PSTHs of the simple and complex spike activities showed that part of PCs in all three different corticonuclear zones responded to the forepaw flexion-extension stimulation, but proportion of the cells affected was quite different among the three zones. In the IZ 84% PCs were modulated by the forepaw stimulation, while in the FZ and DZ it was 59% and 20% respectively. These results support previous finding that information processing involved in the modulation of Purkinje cell activity in response to the forepaw stimulation occurs in all 3 zones examined.