Dash Suryadeep, Yan Xiaogang, Wang Hongying, Crawford John Douglas
Center for Vision Research, York University, Room 0009, Lassonde Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
Center for Vision Research, York University, Room 0009, Lassonde Building, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
Curr Biol. 2015 Feb 2;25(3):267-274. doi: 10.1016/j.cub.2014.11.064. Epub 2015 Jan 15.
Primates can remember and spatially update the visual direction of previously viewed objects during various types of self-motion. It is known that the brain "remaps" visual memory traces relative to gaze just before and after, but not during, discrete gaze shifts called saccades. However, it is not known how visual memory is updated during slow, continuous motion of the eyes.
Here, we recorded the midbrain superior colliculus (SC) of two rhesus monkeys that were trained to spatially update the location of a saccade target across an intervening smooth pursuit (SP) eye movement. Saccade target location was varied across trials so that it passed through the neuron's receptive field at different points of the SP trajectory. Nearly all (99% of) visual responsive neurons, but no motor neurons, showed a transient memory response that continuously updated the saccade goal during SP. These responses were gaze centered (i.e., shifting across the SC's retinotopic map in opposition to gaze). Furthermore, this response was strongly enhanced by attention and/or saccade target selection.
This is the first demonstration of continuous updating of visual memory responses during eye motion. We expect that this would generalize to other visuomotor structures when gaze shifts in a continuous, unpredictable fashion.
灵长类动物在各种类型的自身运动过程中能够记住并在空间上更新先前看到物体的视觉方向。已知大脑在离散的称为扫视的注视转移之前和之后（而非在扫视期间）会相对于注视“重新映射”视觉记忆痕迹。然而，尚不清楚在眼睛缓慢、连续运动期间视觉记忆是如何更新的。
在此，我们记录了两只恒河猴的中脑上丘（SC），它们经过训练可在一次中间的平稳跟踪（SP）眼动过程中在空间上更新扫视目标的位置。在不同试验中改变扫视目标位置，使其在SP轨迹的不同点穿过神经元的感受野。几乎所有（99%的）视觉反应神经元而非运动神经元，在SP期间均表现出一种瞬时记忆反应，该反应会持续更新扫视目标。这些反应以注视为中心（即相对于注视在SC的视网膜拓扑图上移动）。此外，这种反应通过注意力和/或扫视目标选择得到强烈增强。
这是首次证明在眼动期间视觉记忆反应的连续更新。我们预计，当注视以连续、不可预测的方式移动时，这将推广到其他视觉运动结构。
