Nature2014-06-24 3:07 PM

 快速眼睛运动与视觉感知 Visual space is compressed in prefrontal cortex before eye movements

论文摘要 

当我们看一个视觉场景时,我们会做快速眼睛运动 (被称为“扫视”),它们将该场景的不同部分带给“中央凹”(视网膜最敏锐的区域)。这些眼睛运动造成视网膜的图像发生实质性偏移,但我们对视觉世界的感觉却是稳定的和连续的。Tirin Moore及同事在额叶前部神经元中发现这种稳定性的一个可能机制。他们显示,在眼睛运动的准备过程中,神经元对它们的视觉感知场 (神经元对其反应性最强的空间区域)进行移动,以便大规模地过度表达与行为相关的区域,这与人类视觉感知是一致的。这些发现与一个长期被人们接受的假说相矛盾,后者认为“感受野”会预测性地进行重测,基于对每次眼睛运动的结果的预期来通过脑中的神经元改变对视觉空间的表达。

Abstract 

We experience the visual world through a series of saccadic eye movements, each one shifting our gaze to bring objects of interest to the fovea for further processing. Although such movements lead to frequent and substantial displacements of the retinal image, these displacements go unnoticed. It is widely assumed that a primary mechanism underlying this apparent stability is an anticipatory shifting of visual receptive fields (RFs) from their presaccadic to their postsaccadic locations before movement onset. Evidence of this predictive ‘remapping’ of RFs has been particularly apparent within brain structures involved in gaze control. However, critically absent among that evidence are detailed measurements of visual RFs before movement onset. Here we show that during saccade preparation, rather than remap, RFs of neurons in a prefrontal gaze control area massively converge towards the saccadic target. We mapped the visual RFs of prefrontal neurons during stable fixation and immediately before the onset of eye movements, using multi-electrode recordings in monkeys. Following movements from an initial fixation point to a target, RFs remained stationary in retinocentric space. However, in the period immediately before movement onset, RFs shifted by as much as 18 degrees of visual angle, and converged towards the target location. This convergence resulted in a threefold increase in the proportion of RFs responding to stimuli near the target region. In addition, like in human observers, the population of prefrontal neurons grossly mislocalized presaccadic stimuli as being closer to the target. Our results show that RF shifts do not predict the retinal displacements due to saccades, but instead reflect the overriding perception of target space during eye movements.

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