STUDY ON THE RECONSTRUCTION OF VISUAL PATHWAYS

1. 猫视神经再生的研究1)作为先前研究的延续，我们记录了260个坐骨神经纤维的视觉反应单位，视网膜神经节细胞轴突通过这些纤维再生。我们证实了Y细胞的数量多于X和其他细胞，并进一步发现在X细胞中没有OFF中心细胞，而在Y细胞中同时采样了ON和OFF。2)用生物细胞素顺行标记后，我们研究了再生的猫视神经轴突的横切面，发现大多数轴突是无髓鞘的，即使有髓鞘纤维的直径范围也比正常视神经轴突的直径范围小。3)采用逆行标记法联合细胞内注射路西法黄，观察视神经切片后存活2个月的神经节细胞形态。与其他细胞类型相比，α (Y)细胞对轴切开术的抵抗力最强。用周围神经移植重建视网膜颈突的成年仓鼠，研究其视力的恢复情况。在以光刺激作为条件刺激的条件回避行为过程中，4只仓鼠中有2只的视力得到了相对恢复。对于这两只动物，我们成功地通过WGA-HRP顺行标记将再生的视网膜轴突追踪到上丘。此外，我们成功地在周围神经移植物桥接到眼丘的光刺激后获得脑电图不同步。视神经切片后2 ~ 30天，观察BDNF、NT3、NT4等神经营养因子对视网膜神经节细胞轴突再生的影响。细胞内注射神经生物素显示了整个支架内再生轴突的详细形态，如循环轴突和侧分支。发现BDNF最有效地增加了偶有侧分支的重复轴突的数量。少

1. Studies on optic nerve regeneration in cats1) As a continuation of the previous study we recorded 260 visually responsive units from teased fibers of the sciatic nerve through which retinal ganglions cell axon regenerated. We confirmed the outnumber of Y cells than X and other cells and further found that among X cells there was no OFF center cell while in Y cells both ON and OFF were sampled. 2) After anterograde labeling with biocytin we studied the cross section of the regenerated optic axons and found that most of the axons were unmyelinated and the diameter range was smaller even among myelinated fibers as compared with the diameter range of normal optic axons in cats. 3) Morphological types of ganglions cells which survived for 2 months after optic nerve section were studied by a retrograde labeling method coupled with intracellular injections of Lucifer Yellow. alpha (Y)cells turned out to be the most resistant to axotomy over the other cells types.2. Functional recovery of v … More ision was studied in adult hamsters with a reconstructed retinocolliclar projection by the peripheral nerve transplant. In two hamsters out of four relative recovery of vision was obtained in avoidance score during the session of conditioned avoidance behavior using a light stimuli as a conditioning stimulus. For these two animals we succeed to trace regenerated retinal axons into the superior colliculus by an anterograde labeling with WGA-HRP. Furthermore we succeeded to obtain EEG desynchronization after photic stimulation into the eye which was bridged to the colliculus with a peripheral nerve graft.3. Effects of neurotrophic factors such BDNF, NT3, NT4 on axonal regeneration of retinal ganglion cells were studied 2-30 days after optic nerve section. Intracellular injections of neurobiotin revealed detailed morphology of regenerating axons such as recurring axons and side branches within the whole mount preparation. BDNF was found most effective to increase the number of recurring axons with occasional side branches. Less