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Suppression mechanisms of brainstem saccade generator by the caudal superior colliculus - Neural mechanisms of visual fixation -

尾上丘对脑干扫视发生器的抑制机制 - 视觉固定的神经机制 -

基本信息

批准号：
17500271
负责人：
SUGIUCHI Yuriko
金额：
$ 2.24万
依托单位：
Tokyo Medical and Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17500271/
关键词：
superior colliculus inhibitory burst neuron pause neuron saccade visual fixation

项目摘要

The superior colliculus (SC) controls saccadic eye movement. In the SC, there is a motor map that reflects directions and amplitudes of saccades. Recently, it was proposed that neurons in the rostral SC maybe specifically involved in controlling fixation and suppressing saccades. Therefore, the rostral part of the SC is called the "fixation zone", whereas the remaining caudal part is called the "saccade zone". However, it was also reported that most fixation neurons do not pause for small contraversive saccades, but increase their activity. This finding has led the idea that fixation neurons are only the rostral extension of the saccade-related neurons in the more caudal colliculus. Therefore, the functional independence of the fixation zone in the rostral part has been controversial. In order to analyze the functional independence of the rostral part of the SC, we analyzed the neural connections from the rostral and caudal parts of the SC to inhibitory burst neurons (IBNs) and omnipause neurons (OPNs) using intracellular recording and straining methods in anesthetized cats.IBNs received monosynaptic excitatory postsynaptic potentials (EPSPs) from the contralateral caudal SC. They received disynaptic inhibitory postsynaptic potentials (IPSPs) from the ipsilateral caudal SC and bilateral rostral SCs. Lesion experiment suggested that the disynaptic IPSPs from the rostral parts of the bilateral SC was mediated by OPNs, and this was confirmed by the electrophysiological evidence. OPNs received monosynaptic EPSPs from the bilateral rostral SCs, and intracellular straining of such neurons showed projection to the contralateral excitatory burst neuron and IBN regions. These results indicate that the rostral of the SC directly activate OPNs and disynaptically inhibit IBNs via OPNs. The different pattern of synaptic input from the rostral and caudal SC to IBNs and OPNs indicated functional difference of the rostral part of the SC from its caudal part.

上级丘（SC）控制扫视眼球运动。在SC中，存在反映扫视的方向和幅度的运动图。最近，有人提出，在吻侧SC的神经元可能专门参与控制注视和抑制扫视。因此，SC的吻侧部分被称为“注视区”，而其余的尾侧部分被称为“扫视区”。然而，也有报道称，大多数注视神经元不会因为小的逆向扫视而暂停，而是增加了它们的活性。这一发现导致了这样的想法，即注视神经元只是尾侧丘中与扫视相关的神经元的吻侧延伸。因此，吻侧部注视区的功能独立性一直存在争议。为了分析SC吻侧部的功能独立性，在麻醉猫的尾侧SC上，我们用细胞内记录和应变的方法，分析了SC的头、尾侧与抑制性爆发神经元（IBN）和全休止神经元（OPN）的神经联系。IBN接受对侧尾侧SC的单突触兴奋性突触后电位（EPSP），它们接受双突触抑制性突触后电位（IPSPs）。损伤实验表明，双侧SC吻侧部的IPSPs是由OPNs介导的，这一点得到了电生理学的证实。OPNs接受单突触的EPSP从双边吻SC，和细胞内应变的神经元表现出对侧兴奋性爆发神经元和IBN区域的投影。这些结果表明，SC的吻端直接激活OPNs，并通过OPNs双突触抑制IBNs。SC吻侧和尾侧对IBNs和OPNs的突触传入模式不同，表明SC吻侧和尾侧的功能不同。