A circuit for saccadic suppression in the primate brain
A circuit for saccadic suppression in the primate brain
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DOI：
10.1152/jn.00679.2016
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发表时间：
2017-04-01
影响因子：
2.5
通讯作者：
Wurtz, Robert H.
中科院分区：
文献类型：
--
作者：
Berman, Rebecca A.;Cavanaugh, James;Wurtz, Robert H.
当眼睛扫过视觉场景时，眼跳应该使我们看到模糊的东西。特定的大脑机制通过在眼跳期间产生抑制来防止这种情况发生。这种抑制的神经元相关性首先在上丘（SC）的视觉浅层中建立，随后在皮层视觉区域（包括中颞视觉区域（MT））中观察到。在这项研究中，我们研究了最近发现的一条通过下丘脑 (PI) 连接视觉 SC (SC) 和 MT 的回路的抑制情况。我们检查了对眼跳之前出现的视觉刺激的反应，以揭示由眼跳命令副本驱动的神经元相关抑制，称为推论放电。我们发现 SC、PI 和 MT 中的视觉反应同样受到抑制。在每个区域内，视觉反应的抑制随着眼跳进入两个视觉半视野而发生，但只有在对侧半视野中，这种抑制始终在眼跳之前开始（类似于 100 毫秒）。电路中信号的一致性使我们推测 MT 中的抑制受到 SC 输入的影响。我们通过灭活 SC 内的神经元在一只猴子身上测试了这一假设，并发现了 MT 抑制取决于来自运动 SC (SCi) 的必然放电信号的证据。将这些结果与最近在啮齿类动物中的发现相结合，我们提出了一个完整的电路，该电路源自 SCi 中的推论放电信号，该电路在视觉 SC、PI 以及最终的 MT 皮层中产生抑制。新的和值得注意的视觉神经科学的一个基本难题是，我们经常进行快速的眼球运动（扫视），但很少感知到每次运动所伴随的视觉模糊。我们通过记录和扰乱最近发现的从脑干到皮层的回路来研究这种扫视抑制的神经元相关性。我们在每个阶段都发现了抑制，有证据表明它是由内部生成的信号驱动的。我们得出的结论是，该电路有助于眼球运动期间视觉信号的神经元抑制。
Saccades should cause us to see a blur as the eyes sweep across a visual scene. Specific brain mechanisms prevent this by producing suppression during saccades. Neuronal correlates of such suppression were first established in the visual superficial layers of the superior colliculus (SC) and subsequently have been observed in cortical visual areas, including the middle temporal visual area (MT). In this study, we investigated suppression in a recently identified circuit linking visual SC (SCs) to MT through the inferior pulvinar (PI). We examined responses to visual stimuli presented just before saccades to reveal a neuronal correlate of suppression driven by a copy of the saccade command, referred to as a corollary discharge. We found that visual responses were similarly suppressed in SCs, PI, and MT. Within each region, suppression of visual responses occurred with saccades into both visual hemifields, but only in the contralateral hemifield did this suppression consistently begin before the saccade (similar to 100 ms). The consistency of the signal along the circuit led us to hypothesize that the suppression in MT was influenced by input from the SC. We tested this hypothesis in one monkey by inactivating neurons within the SC and found evidence that suppression in MT depends on corollary discharge signals from motor SC (SCi). Combining these results with recent findings in rodents, we propose a complete circuit originating with corollary discharge signals in SCi that produces suppression in visual SCs, PI, and ultimately, MT cortex.NEW & NOTEWORTHY A fundamental puzzle in visual neuroscience is that we frequently make rapid eye movements (saccades) but seldom perceive the visual blur accompanying each movement. We investigated neuronal correlates of this saccadic suppression by recording from and perturbing a recently identified circuit from brainstem to cortex. We found suppression at each stage, with evidence that it was driven by an internally generated signal. We conclude that this circuit contributes to neuronal suppression of visual signals during eye movements.