Santoni Alessia, Di Dona Giuseppe, Melcher David, Franchin Laura, Ronconi Luca
School of Psychology, Vita-Salute San Raffaele University, 20132 Milan, Italy.
Department of Psychology and Cognitive Science, University of Trento, 38068 Rovereto, Italy; Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
Neuroimage Clin. 2025;45:103720. doi: 10.1016/j.nicl.2024.103720. Epub 2024 Dec 1.
Temporal processing deficits in Developmental Dyslexia (DD) have been documented extensively at the behavioral level, leading to the formulation of neural theories positing that such anomalies in parsing multisensory input rely on aberrant synchronization of neural oscillations or to an excessive level of neural noise. Despite reading being primarily supported by visual functions, experimental evidence supporting these theories remains scarce. Here, we tested 26 adults with DD (9 females) and 31 neurotypical controls (16 females) with a temporal segregation/integration task that required participants to either integrate or segregate two rapidly presented displays while their EEG activity was recorded. We confirmed a temporal sampling deficit in DD, which specifically affected the rapid segregation of visual input. While the ongoing alpha frequency and the excitation/inhibition (E/I) ratio (i.e., an index of neural noise quantified by the aperiodic exponent) were differently modulated based on task demands in typical readers, DD participants exhibited an impairment in alpha speed modulation and an altered E/I ratio that affected their rapid visual sampling. Nonetheless, an association between visual temporal sampling accuracy and both alpha frequency and the E/I ratio measured at rest were evident in the DD group, further confirming an anomalous interplay between alpha synchronization, the E/I ratio and active visual sampling. These results provide evidence that both trait- and state-like differences in alpha-band synchronization and neural noise levels coexist in the dyslexic brain and are synergistically responsible for cascade effects on visual sampling and reading.
发育性阅读障碍（DD）中的时间处理缺陷在行为层面已有广泛记录，这促使人们形成了神经理论，认为在解析多感官输入时的此类异常依赖于神经振荡的异常同步或过高水平的神经噪声。尽管阅读主要由视觉功能支持，但支持这些理论的实验证据仍然很少。在这里，我们对26名患有DD的成年人（9名女性）和31名神经典型对照者（16名女性）进行了一项时间分离/整合任务测试，该任务要求参与者在记录脑电图活动的同时，要么整合要么分离两个快速呈现的显示。我们证实了DD患者存在时间采样缺陷，这特别影响了视觉输入的快速分离。虽然在典型阅读者中，持续的阿尔法频率和兴奋/抑制（E/I）比（即通过非周期性指数量化的神经噪声指标）会根据任务需求进行不同的调制，但DD参与者在阿尔法速度调制方面存在损伤，且E/I比发生改变，这影响了他们的快速视觉采样。尽管如此，在DD组中，视觉时间采样准确性与静息时测量的阿尔法频率和E/I比之间存在明显关联，进一步证实了阿尔法同步、E/I比和主动视觉采样之间存在异常相互作用。这些结果提供了证据，表明在阅读障碍大脑中，阿尔法波段同步和神经噪声水平的特质性和状态性差异并存，并协同导致对视觉采样和阅读的级联效应。
