Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada.
J Cogn Neurosci. 2013 Oct;25(10):1754-68. doi: 10.1162/jocn_a_00429. Epub 2013 May 22.
The mechanisms that underlie the integration of visual and goal-related signals for the production of saccades remain poorly understood. Here, we examined how spatial proximity of competing stimuli shapes goal-directed responses in the superior colliculus (SC), a midbrain structure closely associated with the control of visual attention and eye movements. Monkeys were trained to perform an oculomotor-capture task [Theeuwes, J., Kramer, A. F., Hahn, S., Irwin, D. E., & Zelinsky, G. J. Influence of attentional capture on oculomotor control. Journal of Experimental Psychology. Human Perception and Performance, 25, 1595-1608, 1999], in which a target singleton was revealed via an isoluminant color change in all but one item. On a portion of the trials, an additional salient item abruptly appeared near or far from the target. We quantified how spatial proximity between the abrupt-onset and the target shaped the goal-directed response. We found that the appearance of an abrupt-onset near the target induced a transient decrease in goal-directed discharge of SC visuomotor neurons. Although this was indicative of spatial competition, it was immediately followed by a rebound in presaccadic activation, which facilitated the saccadic response (i.e., it induced shorter saccadic RT). A similar suppression also occurred at most nontarget locations even in the absence of the abrupt-onset. This is indicative of a mechanism that enabled monkeys to quickly discount stimuli that shared the common nontarget feature. These results reveal a pattern of excitation/inhibition across the SC visuomotor map that acted to facilitate optimal behavior-the short duration suppression minimized the probability of capture by salient distractors, whereas a subsequent boost in accumulation rate ensured a fast goal-directed response. Such nonlinear dynamics should be incorporated into future biologically plausible models of saccade behavior.
视觉和与目标相关的信号整合的机制对于产生眼跳仍然知之甚少。在这里，我们研究了竞争刺激的空间接近度如何塑造中脑结构上丘（SC）中的目标导向反应，该结构与视觉注意力和眼球运动的控制密切相关。猴子被训练执行眼动捕获任务[Theeuwes，J.，Kramer，A. F.，Hahn，S.，Irwin，D. E.，& Zelinsky，G. J.注意力捕获对眼动控制的影响。实验心理学杂志。人类感知与表现，25，1595-1608，1999]，其中通过除一个项目之外的所有项目的等亮度颜色变化来揭示目标单。在一部分试验中，一个额外的显著项目突然出现在目标附近或远处。我们量化了突然出现的目标和目标之间的空间接近度如何塑造目标导向的反应。我们发现，目标附近的突然出现会导致 SC 运动神经元的目标导向放电短暂降低。尽管这表明存在空间竞争，但随后会立即出现预眼跳激活的反弹，从而促进眼跳反应（即，它会导致较短的眼跳 RT）。即使在没有突然出现的情况下，在大多数非目标位置也会发生类似的抑制。这表明存在一种机制，使猴子能够快速忽略共享常见非目标特征的刺激。这些结果揭示了 SC 运动图中兴奋/抑制的模式，该模式有助于实现最佳行为-短暂的抑制期最小化了被突出的分心物捕获的可能性，而随后积累率的提高则确保了快速的目标导向反应。这种非线性动力学应该被纳入未来对眼跳行为的生物合理模型。
