Gu Q, Singer W
Max-Planck-Institut für Hirnforschung, Frankfurt 71, Federal Republic of Germany.
EXS. 1989;57:305-14. doi: 10.1007/978-3-0348-9138-7_30.
During a critical period of postnatal development neuronal connections in the visual cortex are susceptible to experience-dependent modifications. In normally reared kittens the majority of neurons respond to visual stimulation of either eye. A few days of monocular deprivation, however, are sufficient to render most cortical neurons unresponsive to visual stimuli presented to the deprived eye. Among other factors the cholinergic projection to striate cortex has been identified as having a permissive role in this use-dependent modification of synaptic transmission. In order to analyze further the influence of acetylcholine in cortical plasticity, we tested whether the blockade of muscarinic or nicotinic receptors interfered with ocular dominance plasticity. At four weeks of age kittens had one eyelid sutured closed and osmotic minipumps implanted, which delivered scopolamine (1 nmol/h) or hexamethonium (1 or 10 nmol/h) into the striate cortex of one hemisphere and vehicle solution (saline) into the other. After one week, ocular dominance distributions were determined in area 17 with single unit recording. In the control hemispheres, most neurons became unresponsive to the deprived eye, while in the scopolamine-treated hemispheres most neurons remained binocular. In contrast to the effects of scopolamine, the intracortical infusion of hexamethonium had no effect on ocular dominance plasticity. These results demonstrate that blockade of muscarinic, but not nicotinic receptors renders kitten striate cortex resistant to the effects of monocular deprivation.
在出生后发育的关键时期，视觉皮层中的神经元连接容易受到经验依赖性修饰的影响。在正常饲养的小猫中，大多数神经元对任何一只眼睛的视觉刺激都会产生反应。然而，几天的单眼剥夺就足以使大多数皮层神经元对呈现给被剥夺眼的视觉刺激无反应。在其他因素中，向纹状皮层的胆碱能投射已被确定在这种突触传递的使用依赖性修饰中起允许作用。为了进一步分析乙酰胆碱在皮层可塑性中的影响，我们测试了毒蕈碱或烟碱受体的阻断是否会干扰眼优势可塑性。在四周龄时，将小猫的一只眼睑缝合，并植入渗透微型泵，该微型泵将东莨菪碱（1 nmol/h）或六甲铵（1或10 nmol/h）输送到一个半球的纹状皮层，将溶剂（生理盐水）输送到另一个半球。一周后，通过单单位记录确定17区的眼优势分布。在对照半球中，大多数神经元对被剥夺的眼睛无反应，而在经东莨菪碱处理的半球中，大多数神经元仍保持双眼性。与东莨菪碱的作用相反，皮层内注入六甲铵对眼优势可塑性没有影响。这些结果表明，阻断毒蕈碱受体而非烟碱受体可使小猫纹状皮层对单眼剥夺的影响产生抗性。
