Cavanaugh James, Berman Rebecca A, Joiner Wilsaan M, Wurtz Robert H
Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892
Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892.
J Neurosci. 2016 Jan 6;36(1):31-42. doi: 10.1523/JNEUROSCI.2054-15.2016.
Saccadic eye movements direct the high-resolution foveae of our retinas toward objects of interest. With each saccade, the image jumps on the retina, causing a discontinuity in visual input. Our visual perception, however, remains stable. Philosophers and scientists over centuries have proposed that visual stability depends upon an internal neuronal signal that is a copy of the neuronal signal driving the eye movement, now referred to as a corollary discharge (CD) or efference copy. In the old world monkey, such a CD circuit for saccades has been identified extending from superior colliculus through MD thalamus to frontal cortex, but there is little evidence that this circuit actually contributes to visual perception. We tested the influence of this CD circuit on visual perception by first training macaque monkeys to report their perceived eye direction, and then reversibly inactivating the CD as it passes through the thalamus. We found that the monkey's perception changed; during CD inactivation, there was a difference between where the monkey perceived its eyes to be directed and where they were actually directed. Perception and saccade were decoupled. We established that the perceived eye direction at the end of the saccade was not derived from proprioceptive input from eye muscles, and was not altered by contextual visual information. We conclude that the CD provides internal information contributing to the brain's creation of perceived visual stability. More specifically, the CD might provide the internal saccade vector used to unite separate retinal images into a stable visual scene.
Visual stability is one of the most remarkable aspects of human vision. The eyes move rapidly several times per second, displacing the retinal image each time. The brain compensates for this disruption, keeping our visual perception stable. A major hypothesis explaining this stability invokes a signal within the brain, a corollary discharge, that informs visual regions of the brain when and where the eyes are about to move. Such a corollary discharge circuit for eye movements has been identified in macaque monkey. We now show that selectively inactivating this brain circuit alters the monkey's visual perception. We conclude that this corollary discharge provides a critical signal that can be used to unite jumping retinal images into a consistent visual scene.
扫视眼动将我们视网膜的高分辨率中央凹对准感兴趣的物体。每次扫视时，图像在视网膜上跳跃，导致视觉输入出现间断。然而，我们的视觉感知保持稳定。几个世纪以来，哲学家和科学家们提出，视觉稳定性依赖于一种内部神经元信号，它是驱动眼动的神经元信号的副本，现在被称为伴随放电（CD）或传出副本。在旧世界猴中，已经确定了这样一个用于扫视的CD回路，它从上丘延伸穿过丘脑腹内侧核到达额叶皮层，但几乎没有证据表明这个回路实际上对视觉感知有贡献。我们通过首先训练猕猴报告它们感知到的眼睛方向，然后在CD通过丘脑时可逆地使其失活，来测试这个CD回路对视觉感知的影响。我们发现猴子的感知发生了变化；在CD失活期间，猴子感知到的眼睛指向位置与实际指向位置之间存在差异。感知和扫视解耦了。我们确定扫视结束时感知到的眼睛方向不是来自眼肌的本体感觉输入，也不会被背景视觉信息改变。我们得出结论，CD提供内部信息，有助于大脑创造感知到的视觉稳定性。更具体地说，CD可能提供用于将单独的视网膜图像统一成稳定视觉场景的内部扫视向量。
视觉稳定性是人类视觉最显著的方面之一。眼睛每秒快速移动几次，每次都会使视网膜图像移位。大脑会补偿这种干扰，使我们的视觉感知保持稳定。一个解释这种稳定性的主要假设引入了大脑中的一种信号，即伴随放电，它在眼睛即将移动时通知大脑的视觉区域眼睛的移动时间和位置。在猕猴中已经确定了这样一个用于眼动的伴随放电回路。我们现在表明，选择性地使这个大脑回路失活会改变猴子的视觉感知。我们得出结论，这种伴随放电提供了一个关键信号，可用于将跳跃的视网膜图像统一成一致的视觉场景。
