Kehoe Devin H, Rahimi Maryam, Fallah Mazyar
Department of Psychology, York University, Toronto, ON, Canada.
Centre for Vision Research, York University, Toronto, ON, Canada.
Front Syst Neurosci. 2018 Jan 26;12:1. doi: 10.3389/fnsys.2018.00001. eCollection 2018.
The oculomotor system utilizes color extensively for planning saccades. Therefore, we examined how the oculomotor system actually encodes color and several factors that modulate these representations: attention-based surround suppression and inherent biases in selecting and encoding color categories. We measured saccade trajectories while human participants performed a memory-guided saccade task with color targets and distractors and examined whether oculomotor target selection processing was functionally related to the CIE (,) color space distances between color stimuli and whether there were hierarchical differences between color categories in the strength and speed of encoding potential saccade goals. We observed that saccade planning was modulated by the CIE (,) distances between stimuli thus demonstrating that color is encoded in perceptual color space by the oculomotor system. Furthermore, these representations were modulated by (1) cueing attention to a particular color thereby eliciting surround suppression in oculomotor color space and (2) inherent selection and encoding biases based on color category independent of cueing and perceptual discriminability. Since surround suppression emerges from recurrent feedback attenuation of sensory projections, observing oculomotor surround suppression suggested that oculomotor encoding of behavioral relevance results from integrating sensory and cognitive signals that are pre-attenuated based on task demands and that the oculomotor system therefore does not functionally contribute to this process. Second, although perceptual discriminability did partially account for oculomotor processing differences between color categories, we also observed preferential processing of the red color category across various behavioral metrics. This is consistent with numerous previous studies and could not be simply explained by perceptual discriminability. Since we utilized a memory-guided saccade task, this indicates that the biased processing of the red color category does not rely on sustained sensory input and must therefore involve cortical areas associated with the highest levels of visual processing involved in visual working memory.
动眼系统在扫视计划中广泛利用颜色。因此，我们研究了动眼系统实际如何编码颜色以及调节这些表征的几个因素：基于注意力的周边抑制以及在选择和编码颜色类别时的固有偏差。我们在人类参与者执行带有颜色目标和干扰物的记忆引导扫视任务时测量了扫视轨迹，并研究了动眼目标选择处理是否在功能上与颜色刺激之间的CIE（，）颜色空间距离相关，以及在编码潜在扫视目标的强度和速度方面颜色类别之间是否存在层次差异。我们观察到扫视计划受到刺激之间的CIE（，）距离的调节，从而证明动眼系统在感知颜色空间中对颜色进行编码。此外，这些表征受到以下因素的调节：（1）将注意力引导至特定颜色，从而在动眼颜色空间中引发周边抑制；（2）基于颜色类别的固有选择和编码偏差，与提示和感知辨别力无关。由于周边抑制源于感觉投射的循环反馈衰减，观察到动眼周边抑制表明，行为相关性的动眼编码是基于任务需求对预先衰减的感觉和认知信号进行整合的结果，因此动眼系统在功能上对这一过程没有贡献。其次，尽管感知辨别力确实部分解释了颜色类别之间的动眼处理差异，但我们还观察到在各种行为指标上红色类别具有优先处理。这与之前的众多研究一致，并且不能简单地用感知辨别力来解释。由于我们使用了记忆引导扫视任务，这表明红色类别的偏向处理不依赖于持续的感觉输入，因此必须涉及与视觉工作记忆中涉及的最高水平视觉处理相关的皮质区域。
