Waleszczyk Wioletta J, Wang Chun, Benedek György, Burke William, Dreher Bogdan
Department of Neurophysiology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
Acta Neurobiol Exp (Wars). 2004;64(2):209-28. doi: 10.55782/ane-2004-1507.
It is well established that neurons in the retinorecipient layers of superior colliculus (SC), the mammalian homologue of the optic tectum of other vertebrates, are extremely sensitive to moving stimuli. In our studies we have distinguished several functionally distinct groups of neurons in the retinorecipient layers of the SC of the cat on the basis of their velocity response profiles. Our data revealed substantial convergence of the Y and non-Y information channels on single SC neurons. Second, using the method of selective conduction block of the Y-type fibers in one optic nerve we have shown that responses of SC cells to high-velocity motion are dependant on the integrity of Y-type input. Third, in order to determine the degree of influence of the X- and W-type input on cellular responses we have examined spatial and temporal frequency response profiles of single collicular neurons using sinusoidal gratings drifting in the preferred direction. At any given eccentricity, most collicular neurons exhibited a preference for relatively very low spatial frequencies. The preference for low spatial frequencies combined with temporal frequency profiles of collicular neurons suggests that the Y- and W-type inputs constitute the major functional inputs to the retinorecipient layers of the SC and that the "top-down" X-type input from the visual cortex has only a minor impact on the spatio-temporal frequency response profiles of collicular receptive fields.
众所周知，上丘（SC）的视网膜接受层中的神经元，即其他脊椎动物视顶盖的哺乳动物同源物，对移动刺激极为敏感。在我们的研究中，我们根据猫的SC视网膜接受层中神经元的速度反应曲线，区分出了几个功能上不同的神经元群体。我们的数据显示，Y和非Y信息通道在单个SC神经元上有大量汇聚。其次，通过在一条视神经中选择性阻断Y型纤维传导的方法，我们表明SC细胞对高速运动的反应依赖于Y型输入的完整性。第三，为了确定X型和W型输入对细胞反应的影响程度，我们使用在偏好方向漂移的正弦光栅，检查了单个上丘神经元的空间和时间频率反应曲线。在任何给定的离心率下，大多数上丘神经元表现出对相对非常低的空间频率的偏好。对低空间频率的偏好与上丘神经元的时间频率曲线相结合，表明Y型和W型输入构成了SC视网膜接受层的主要功能输入，而来自视觉皮层的“自上而下”X型输入对丘接受野的时空频率反应曲线只有轻微影响。
