猫外膝体神经元非寻常的方位调谐特性──Ⅱ．在去视皮层猫和视觉剥夺猫（Dark－reared　cats）的研究

UNSUAL ORIENTATION TUNING CURVE OF LGNd RELAY CELLS IN THE CAT: Ⅱ.STUDIES IN DECORTICATE CATS AND DARK-REARED CATS

以移动的正弦光栅作为刺激，用玻璃微电极记录以冰冻法毁损皮层１７、１８、１９区和外侧上雪氏回（ＬＳ）区后的猫外膝体的单细胞反应，测定了了５７９个细胞的方位调谐特性．另外还在视觉剥夺猫外膝体测定了３４４个细胞的方位调谐特性．与正常猫相似，去视皮层猫和视觉剥夺猫外膝体的少数细胞（约占１０％）具有非寻常的方位调谐特性，包括具蝴蝶形调谐曲线的方位调谐特性、双调谐（Ｂｉｍｏｄａｌ）的方位调谐特性和最优方位随刺激空间频率的不同而变化的方位调谐特性。结果表明，外膝体的非寻常的方位调谐特性并非主要由皮层下行投射所致，而是主要与先天遗传因素有关。

Single unit responses to sinusoidal drifting gratings were recorded with microcapillary electiodes from the lateral geniculate nudeus (LGNd) in decorticate cats and dark-reared cats.The orientation sensihvity of 596 cells in decorticate cats and 344 cells in dark-reared catswere quantitatively investigated aspedvely.We found that some LGNd oh (about 10%) shoal tmusual orientation tuning curvesin forrthate cats and dark-reared cats similar to those in nounal cats, including"butterfly-shaped", bimodal orientation tuning curves, and that of changing preprrorientation as a function of spatial frequncy. The cells showing unusual orientation tuning propech also exhibited unusual spatial fequency tuning.The findings strongly support the hypothesis that the unusual orientation tuning propresented in the LGNd relay cells are independent on visual experience, but not mainly contributed by visual cortex feedback.