Centre for Human Psychopharmacology Swinburne University of Technology Melbourne, Australia.
Brain and Mind Institute, University of Western Ontario London, Ontario, Canada.
R Soc Open Sci. 2015 Dec 16;2(12):150226. doi: 10.1098/rsos.150226. eCollection 2015 Dec.
Saccadic suppression-the reduction of visual sensitivity during rapid eye movements-has previously been proposed to reflect a specific suppression of the magnocellular visual system, with the initial neural site of that suppression at or prior to afferent visual information reaching striate cortex. Dysfunction in the magnocellular visual pathway has also been associated with perceptual and physiological anomalies in individuals with autism spectrum disorder or high autistic tendency, leading us to question whether saccadic suppression is altered in the broader autism phenotype. Here we show that individuals with high autistic tendency show greater saccadic suppression of low versus high spatial frequency gratings while those with low autistic tendency do not. In addition, those with high but not low autism spectrum quotient (AQ) demonstrated pre-cortical (35-45 ms) evoked potential differences (saccade versus fixation) to a large, low contrast, pseudo-randomly flashing bar. Both AQ groups showed similar differential visual evoked potential effects in later epochs (80-160 ms) at high contrast. Thus, the magnocellular theory of saccadic suppression appears untenable as a general description for the typically developing population. Our results also suggest that the bias towards local perceptual style reported in autism may be due to selective suppression of low spatial frequency information accompanying every saccadic eye movement.
扫视抑制——在快速眼球运动期间视觉敏感性的降低——先前被提议反映了对大细胞视觉系统的特定抑制，抑制的初始神经部位在传入视觉信息到达纹状皮层之前或之时。在自闭症谱系障碍或高自闭症倾向个体中，大细胞视觉通路的功能障碍也与知觉和生理异常有关，这使我们质疑扫视抑制是否在更广泛的自闭症表型中发生改变。在这里，我们表明，高自闭症倾向个体在进行低空间频率光栅的扫视时，与高空间频率光栅相比，表现出更大的扫视抑制，而低自闭症倾向个体则没有。此外，高自闭症商数（AQ）个体而非低 AQ 个体在注视与扫视之间，表现出对大、低对比度、伪随机闪烁棒的前皮质（35-45ms）诱发电位差异。两个 AQ 组在高对比度下的后期（80-160ms）也表现出类似的差异视觉诱发电位效应。因此，扫视抑制的大细胞理论似乎不能作为对典型发育人群的一般描述。我们的结果还表明，在自闭症中报告的对局部知觉风格的偏向可能是由于伴随每次扫视眼动的低频空间频率信息的选择性抑制。
