Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Av. Universidad 3000, Coyoacán, 04510, Ciudad de México, Mexico.
Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada.
Brain Imaging Behav. 2020 Dec;14(6):2450-2463. doi: 10.1007/s11682-019-00196-3.
Children with ADHD show significant deficits in response inhibition. A leading hypothesis suggests prefrontal hypoactivation as a possible cause, though, there is conflicting evidence. We tested the hypoactivation hypothesis by analyzing the response inhibition process within the oculomotor system. Twenty-two children diagnosed with ADHD and twenty control (CTRL) children performed the antisaccade task while undergoing an fMRI study with concurrent eye tracking. This task included a preparatory stage that cued a prosaccade (toward a stimuli) or an antisaccade (away from a stimuli) without an actual presentation of a peripheral target. This allowed testing inhibitory control without the confounding activation from an actual response. The ADHD group showed longer reaction times and more antisaccade direction errors. While both groups showed activations in saccade network areas, the ADHD showed significant hyperactivation in the dorsolateral prefrontal cortex during the preparatory stage. No other areas in the saccade network had significant activation differences between groups. Further ADHD group analysis OFF and ON stimulant medication did not show drug-related activation differences. However, they showed a significant correlation between the difference in OFF/ON preparatory activation in the precuneus, and a decrease in the number of antisaccade errors. These results do not support the hypoactivity hypothesis as an inhibitory control deficit general explanation, but instead suggest less efficiency during the inhibitory period of the antisaccade task in children. Our findings contrast with previous results in ADHD adults showing decreased preparatory antisaccade activity, suggesting a significant age-dependent maturation effect associated to the inhibitory response in the oculomotor system.
患有注意力缺陷多动障碍（ADHD）的儿童在反应抑制方面存在明显缺陷。一个主要的假设认为，前额叶活动不足是可能的原因，但目前证据相互矛盾。我们通过分析眼动系统中的反应抑制过程来检验活动不足假说。22 名被诊断为 ADHD 的儿童和 20 名对照（CTRL）儿童在进行 fMRI 研究的同时进行了反扫视任务，同时进行眼动追踪。该任务包括一个预备阶段，该阶段提示进行正扫视（朝向刺激物）或反扫视（远离刺激物），而不实际呈现外周目标。这允许在没有实际反应激活的情况下测试抑制控制。ADHD 组的反应时间更长，反扫视方向错误更多。虽然两组在扫视网络区域都表现出激活，但 ADHD 组在预备阶段表现出明显的背外侧前额叶皮层过度激活。扫视网络中的其他区域在两组之间没有显著的激活差异。进一步对 ADHD 组进行 OFF 和 ON 兴奋剂药物分析，未显示与药物相关的激活差异。然而，他们发现，在准备阶段，后扣带回中的 OFF/ON 预备激活差异与反扫视错误数量减少之间存在显著相关性。这些结果不支持活动不足假说作为抑制控制缺陷的一般解释，而是表明在儿童反扫视任务的抑制期间效率较低。我们的研究结果与之前 ADHD 成人的研究结果形成对比，后者显示预备性反扫视活动减少，表明与眼动系统抑制反应相关的抑制反应存在显著的年龄依赖性成熟效应。
