Modification of functional architecture of the visual cortex by a developmental pharmacological method

亚板细胞的神经元活动和功能被认为参与了视觉皮层功能结构的形成。我们研究了将kainic酸局部注射到刚出生几天的小猫的视觉皮层的效果。电生理和免疫组织化学检查显示，这种药物操作阻止了正常视觉皮质功能的突触连接的发展。为了详细研究外侧膝状核（LGN）神经元单个轴突的终止模式，采用PHA-L进行顺行示踪实验。结果清楚地表明，在kainic酸处理的视觉皮层中，LGN轴突延伸到通常终止的IV层之外的II-III层。这种LGN轴突的异常终止模式被认为是我们无法在注射kainic酸的皮层中获得视觉反应的原因。我们还研究了kainic酸注入离子对视觉胼胝体投射发育的影响。逆行示踪实验显示，注射kainic酸后，视觉皮层胼胝体投影数量明显减少。对侧视皮层锥体细胞被鉴定为胼胝体神经元。这些结果首次表明，1周龄时注射kainic酸不仅影响了小猫视觉皮层的丘脑皮质投射，而且影响了胼胝体投射。然而，本研究首先证明了轴突与皮层深层细胞（包括下层细胞）的相互作用在视觉皮层中与突触后细胞建立适当的联系并维持它们之间的相互作用起着重要作用。我们将继续研究发育过程中视觉皮层中功能连接形成的分子和细胞机制。少

Neuronal activity and function of subplate cells have been proposed to be involved in the formation of functional architecture of the visual cortex. We have studied the effects of kainic acid injected locally into the visual cortex of a few-days-old kitten. Electrophysiological and immunohistochemical examinations showed that the synaptic connections for normal visuocortical function was prevented to develop by this pharmacological manipulation. In order to examine in detail about the termination pattern of individual axon of neurons in the lateral geniculate nucleus (LGN) , anterograde tracing experiments using PHA-L were performed. The results clearly indicated that LGN axons extended to layr II-III outside the usual termination layr IV in the visual cortex treated with kainic acid. This abnormal termination pattern of LGN axon is considered as a reason why we could not obtain visual responses in the cortex injected with kainic acid. We also examined the effects of kainic acid inject … More ion on the development of the visual callosal projection. Retrograde tracing experiments have shown that the number of the callosal projection to the visual cortex injected with kainic acid was significantly reduced. Larger number of pyramidal cells were identified as callosal neurons in the contralateral visual cortex to the kainic acid injection. These results first demonstrated that the kainic acid injection in the first week of age affected not only thalamocortical projection but also the callosal projection in kitten visual cortex. It is necessary to examine the specificity of kainic acid injection on subplate cells, however, the present study first demonstrated that the interaction of axons with deep cortical cells, including subplate cells plays an important role for establishing appropriate contact to the post synaptic cells and maintaining them in the visual cortex We continue to study molecular and cellular mechanisms of formation of functional connections in the visual cortex during development. Less