Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN, USA; Department of Psychological Sciences, Purdue University, West Lafayette, IN, USA.
Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN, USA.
Cortex. 2023 Dec;169:118-129. doi: 10.1016/j.cortex.2023.08.016. Epub 2023 Oct 4.
Autistic individuals excel at visual search, however, the neural mechanism(s) underlying this advantage remain unclear. The locus coeruleus-norepinephrine (LC-NE) system, which plays a critical role in sensory perception and selective attention, has been shown to function in a persistently elevated state in individuals on the spectrum. However, the relationship between elevated tonic LC-NE activity and accelerated search in autism has not been explored.
To examine the relationship between visual search abilities and resting pupil diameter (an indirect measure of tonic LC-NE activation) in autistic and neurotypical children.
Participants were 24 school-aged autistic children and 24 age- and IQ-matched neurotypical children aged 8-15 years. Children completed two tasks: a resting eye-tracking task and a visual search paradigm. For the resting eye-tracking task, pupil diameter was monitored while participants fixated a central crosshair. For the visual search paradigm, participants were instructed to find the target (vertical line) embedded within an array of tilted (10°) distractor lines. The target was present on 50% of trials, and displayed within set sizes of 18, 24, and 36 items.
Consistent with previous studies, autistic children had significantly larger resting pupil size and searched faster and more efficiently compared to their neurotypical peers. Eye-tracking findings revealed that accelerated search was associated with fewer, not shorter, fixations in the autism group. Autistic children also showed reduced leftward search bias. Larger resting pupil size, indicative of increased tonic activation of the LC-NE system, was associated with greater search efficiency, longer fixation durations, and reduced leftward bias. Finally, within both groups reduced leftward bias was associated with increased autism symptomatology.
Together, these findings add to the existing body of research highlighting superior search in autism, suggest that elevated tonic LC-NE activity may contribute to more efficient search, and link non-social visual-spatial processing strengths to autism symptoms.
自闭症个体在视觉搜索方面表现出色，然而，支持这种优势的神经机制尚不清楚。蓝斑-去甲肾上腺素（LC-NE）系统在感官知觉和选择性注意中起着关键作用，已被证明在谱系个体中持续处于升高状态。然而，自闭症个体中升高的 LC-NE 活动与加速搜索之间的关系尚未得到探索。
研究自闭症和神经典型儿童的视觉搜索能力与静息瞳孔直径（LC-NE 活动的间接测量）之间的关系。
参与者为 24 名学龄自闭症儿童和 24 名年龄和智商匹配的神经典型儿童，年龄在 8-15 岁之间。儿童完成了两项任务：静息眼动追踪任务和视觉搜索范式。在静息眼动追踪任务中，当参与者注视中央十字线时监测瞳孔直径。在视觉搜索范式中，要求参与者在倾斜（10°）干扰线的数组中找到目标（垂直线）。目标在 50%的试验中出现，并在 18、24 和 36 个项目的集合大小中显示。
与先前的研究一致，自闭症儿童的静息瞳孔大小明显更大，与神经典型同龄人相比，搜索速度更快，效率更高。眼动追踪结果表明，加速搜索与自闭症组中更少而不是更短的注视次数相关。自闭症儿童还表现出较小的左偏搜索偏差。较大的静息瞳孔大小，表明 LC-NE 系统的紧张性激活增加，与更大的搜索效率、更长的注视持续时间和减少的左偏偏差相关。最后，在两个组中，减少的左偏偏差与增加的自闭症症状相关。
这些发现共同强调了自闭症中搜索优势的现有研究，表明升高的紧张性 LC-NE 活动可能有助于更有效的搜索，并将非社交视觉空间处理优势与自闭症症状联系起来。
