Schmidt M, van der Togt C, Wahle P, Hoffmann K P
Allgemeine Zoologie und Neurobiologie, Ruhr-Universität Bochum, Germany.
Eur J Neurosci. 1998 May;10(5):1533-43. doi: 10.1046/j.1460-9568.1998.00161.x.
The receptive field properties of neurons in the medial terminal nucleus of the accessory optic system (MTN) that project to the ipsilateral nucleus of the optic tract (NOT) and dorsal terminal nucleus (DTN), as identified by antidromic electrical activation, were analysed in the anaesthetized rat. The great majority (88%) of MTN neurons that were antidromically activated from NOT and DTN preferred downward directed movement of large visual stimuli while the remaining cells preferred upward directed stimulus movement. Distinct retrograde tracer injections into the NOT/DTN and the ipsilateral inferior olive (IO) revealed that no MTN neurons project to both targets. MTN neurons projecting to the ipsilateral NOT/DTN were predominantly found in the ventral part of the MTN, whereas those projecting to the IO were found in the dorsal part of the MTN. In situ hybridization for glutamic acid decarboxylase (GAD) mRNA was used as a marker for GABAergic neurons. Up to 98% of MTN neurons retrogradely labelled from the ipsilateral NOT/DTN also expressed GAD mRNA. Earlier studies have shown that MTN neurons that prefer upward directed stimulus movements are segregated from MTN neurons that prefer downward directed stimulus movements. It also has been demonstrated that directionally selective neurons in the NOT/DTN prefer horizontal stimulus movements and receive an inhibitory input from ipsilateral MTN. Our results indicate that this input is mediated by GABAergic cells in the ventral part of MTN, which to a large extent prefer downward directed stimulus movements, and that the great majority of MTN neurons that prefer upward directed stimulus movements project to other targets one of which possibly is the IO.
在麻醉大鼠中，分析了经逆向电刺激鉴定的、投射至同侧视束核（NOT）和背侧终核（DTN）的副视系统内侧终核（MTN）神经元的感受野特性。从NOT和DTN逆向激活的MTN神经元中，绝大多数（88%）偏好大视觉刺激的向下运动，而其余细胞则偏好向上的刺激运动。向NOT/DTN和同侧下橄榄核（IO）分别注射不同的逆行示踪剂，结果显示没有MTN神经元同时投射至这两个靶点。投射至同侧NOT/DTN的MTN神经元主要位于MTN的腹侧部分，而投射至IO的MTN神经元则位于MTN的背侧部分。使用谷氨酸脱羧酶（GAD）mRNA原位杂交作为GABA能神经元的标志物。高达98%从同侧NOT/DTN逆向标记的MTN神经元也表达GAD mRNA。早期研究表明，偏好向上刺激运动的MTN神经元与偏好向下刺激运动的MTN神经元是分开的。研究还表明，NOT/DTN中的方向选择性神经元偏好水平刺激运动，并接受来自同侧MTN的抑制性输入。我们的结果表明，这种输入是由MTN腹侧部分的GABA能细胞介导的，这些细胞在很大程度上偏好向下的刺激运动，并且绝大多数偏好向上刺激运动的MTN神经元投射至其他靶点，其中之一可能是IO。
