Facilitation of saccade initiation by brainstem cholinergic system
Facilitation of saccade initiation by brainstem cholinergic system
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DOI：
10.1016/s0387-7604(01)00330-8
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发表时间：
2001-12-01
影响因子：
1.7
通讯作者：
Isa, T
中科院分区：
文献类型：
--
作者：
Kobayashi, Y;Saito, Y;Isa, T
众所周知，哺乳动物上丘(SG)的中间层(SGI)接受来自桥小脑脚被盖核(PPTN)前方的胆碱能输入。采用全细胞膜片钳记录技术，在大鼠脑片上观察胆碱能传入对SGI神经元的作用。应用乙酰胆碱(ACh)在SGI神经元诱发烟碱型ACh受体介导的快内向电流。尼古丁引起的去极化增强了N-甲基-D-天冬氨酸受体介导的兴奋性突触后电位成分，降低了SGI神经元对刺激浅层的爆发性反应阈值。因此，传入SGI的胆碱能促进了SC中直接视觉运动通路的信号传递。在视觉引导的眼跳任务中，通过向清醒猴子的SC内微量注射尼古丁，我们探索了这种观察的行为相关性；注射尼古丁增加了快速眼跳的频率，即反应时间极短的眼跳(<；120ms)。对PPTN神经元单位活动的分析表明，一群PPTN神经元在特定方向上以及在注视点偏移与眼跳靶点起始之间的间隙期间，在疲倦的前视跳增加。因此。PPTN神经元可能参与眼跳的执行和准备。所有这些结果解释了脑干胆碱能系统如何促进眼跳的启动机制，推测这可能取决于动物的注意力或警觉水平。(C)2001 Elsevier Science B.V.保留所有权利。
It is well known that the intermediate layer (SGI) of the mammalian superior colliculus (SG) receives cholinergic inputs originating front the pedunculopontine tegmental nucleus (PPTN). The action of the cholinergic input on the SGI neurons was investigated using whole-cell patch-clamp recording technique in slice preparations obtained from rats. Application of acetylcholine (ACh) induced fast inward currents mediated by nicotinic ACh receptors in the SGI neurons. Depolarization induced by nicotine enhanced the N-methyl-D-aspartate receptor-mediated excitatory postsynaptic potential component and lowered the threshold of bursting response in the SGI neurons to stimulation of the superficial layer. Thus, the cholinergic input to the SGI facilitates the signal transmission through the direct visuomotor pathway in the SC. The behavioral correlate of this observation was explored by microinjection of nicotine into the SC of awake monkeys during visually guided saccade task; injection of nicotine increased frequency of express saccades, the saccades with extremely short reaction times (< 120 ms). Analysis of single unit activity of the PPTN neurons revealed that a population of the PPTN neurons increased tiring preceding saccades in a particular direction and also during the GAP period between the offset of fixation point and onset of the saccade target. Thus. PPTN neurons may be involved in execution and preparation of saccades. All these results explain the mechanisms of how the brainstem cholinergic system facilitates initiation of saccades presumably depending on attention or vigilance level of the animal. (C) 2001 Elsevier Science B.V. All rights reserved.