视皮层反馈对猫外膝体神经元方位调制特性的影响

Influence of Cortical Feedback Project on the Orientation Modulation Properties of dLGN Cells of Cat

以扫描正弦光栅作为刺激 ,用冰冻法毁损皮层 17、 18、 19区和外侧上雪氏回 (LS区 )来阻断皮层对外膝体的反馈投射 ,记录并描绘了猫外膝体 5 97个细胞的方位调制特性 .去视皮层猫外膝体神经元的平均方位选择性强度 (Bias)为 0 15 4,与正常猫 (0 15 5 )几乎相同 ,其最优方位偏向于水平方位 .与正常猫外膝体不同的是 ,去视皮层猫外膝体失去了最优方位的切向分布规律 ,用GABA或KCl压抑皮层活动得到了相近的实验结果 .结果说明正常外膝体的最优方位切向分布规律来自皮层反馈投射 .

The orientation modulation properties of 597 cells in cat dLGN were studied using drifting sinusoidal grating as stimulus, while the feedback project from cortex was blocked through cortical ablation (including area 17, 18, 19 and LS). The average orientation bias of neurons was 0.154 in dLGN of decortiate cats, similar to that of normal cats (0.155). The optimal orientation tended to horizontal in decortiate cats as that in normal cats. However, the cells lossed the tangent distribution of the optimal orientation in decortiate cats. Similar results were observed in cats whose visual cortex were silenced by GABA or KCl. The results suggested that the tangent distribution of the optimal orientation in normal dLGN was generated from the feedback projection from visual cortex.