DEVELOPMENTAL STUDIES OF THE VISUAL SYSTEM

本文提出的研究将调查产后 猫视网膜-膝状体-皮质通路的发育。 本研究共进行了四组实验：（1）在正常条件下， 被剥夺的猫，背侧电路的结构发展 外侧膝状体核（LGN）和初级视皮层（区 17)被认为使用γ-氨基丁酸（GABA）作为 神经递质将用光和电子来研究 显微免疫细胞化学，使用特定的抗体， 对抗GABA (2)替代电气的效果 刺激视网膜神经节细胞（RGC）动作电位 视网膜膝状体突触的形态发育将是 通过眼内注射 河豚毒素（TTX），消除RGC动作电位，而 用植入的电极刺激视神经束。 在 此外，GABA阳性神经元和终末的发育 还将在注射TTX的猫中研究LGN和17区的 利用光镜和电镜免疫细胞化学。 (3)的 视网膜神经节细胞的形态学 接受大的视觉皮层损伤的成年猫（区域17， 18和19）在出生时将通过直接细胞内 辣根过氧化物酶标记单个神经节细胞 （HRP）。 (4)正常和剥夺的突触组织 膝状皮质轴突将通过结合电子 显微镜与HRP细胞内注射到 生理学鉴定的膝状皮质纤维。 这项研究的长期目标是进一步促进我们的 了解视觉系统的出生后发育 在正常和非正常情况下。 特别令人感兴趣的是： (a)模式化的冲动活动在 视网膜-膝状体-皮质通路的形态发育; 和（B）允许补偿性重组的因素 早期病变后的中央视觉通路。 意图是 这项工作将阐明有助于实现这一目标的机制。 弱视的影响或由视力损害引起的后遗症， 中央视觉结构。

The research proposed here will investigate the postnatal development of the retino-geniculo-cortical pathway in the cat. Four sets of experiments are described: (1) In normal and visually deprived cats, the structural development of circuits in the dorsal lateral geniculate nucleus (LGN) and primary visual cortex (area 17) that are thought to use gamma-aminobutyric acid (GABA) as a neurotransmitter will be studied with light and electron microscopic immunocytochemistry, using specific antibodies made against GABA. (2) The effect of substituting electrical stimulation for retinal ganglion cell (RGC) action potentials on the morphological development of retinogeniculate synapses will be investigated by rearing cats with intraocular injection of tetrodotoxin (TTX), to abolish RGC action potentials, while stimulating the optic tract with implanted electrodes. In addition, the development of GABA-positive neurons and terminals in the LGN and area 17 will also be studies in TTX-injected cats using light and electron microscopic immunocytochemistry. (3) The morphology of physiologically classified retinal ganglion cells in adult cats that received a large lesion of visual cortex (areas 17, 18, and 19) at birth will be determined by direct intracellular labeling of single ganglion cells with horseradish peroxidase (HRP). (4) The synaptic organization of normal and deprived geniculocortical axons will be clarified by combining electron microscopy with the intracellular injection of HRP into physiologically identified geniculocortical fibers. The long-term objective of this research is to further our understanding of the postnatal development of the visual system under normal and abnormal conditions. Of particular interest is: (a) the role played by patterned impulse activity in the morphological development of the retino-geniculo-cortical pathway; and (b) the factors that permit compensatory reorganization in the central visual pathway after early lesions. It is intended that this work will shed light on the mechanisms that contribute to the effects of amblyopia or the sequelae that result from damage to central visual structures.