Habib Michel
Cognitive Neuroscience Laboratory, Neurodys Institute, Aix-Marseille University, UMR 7291 Marseille, France.
Brain Sci. 2021 May 27;11(6):708. doi: 10.3390/brainsci11060708.
In a now-classic article published a couple of decades ago (Brain, 2000; 123: 2373-2399), I proposed an "extended temporal processing deficit hypothesis of dyslexia", suggesting that a deficit in temporal processing could explain not only language-related peculiarities usually noticed in dyslexic children, but also a wider range of symptoms related to impaired processing of time in general. In the present review paper, I will revisit this "historical" hypothesis both in the light of a new clinical perspective, including the central yet poorly explained notion of comorbidity, and also taking a new look at the most recent experimental work, mainly focusing on brain imaging data. First, consistent with daily clinical practice, I propose to distinguish three groups of children who fail to learn to read, of fairly equal occurrence, who share the same initial presentation (difficulty in mastering the rules of grapheme-phoneme correspondence) but with differing associated signs and/or comorbid conditions (language disorders in the first group, attentional deficits in the second one, and motor coordination problems in the last one), thus suggesting, at least in part, potentially different triggering mechanisms. It is then suggested, in the light of brain imaging information available to date, that the three main clinical presentations/associations of cognitive impairments that compromise reading skills acquisition correspond to three distinct patterns of miswiring or "disconnectivity" in specific brain networks which have in common their involvement in the process of learning and their heavy reliance on temporal features of information processing. With reference to the classic temporal processing deficit of dyslexia and to recent evidence of an inability of the dyslexic brain to achieve adequate coupling of oscillatory brain activity to the temporal features of external events, a general model is proposed according to which a common mechanism of temporal uncoupling between various disconnected-and/or mis-wired-processors may account for distinct forms of specific learning disorders, with reading impairment being a more or less constant feature. Finally, the potential therapeutic implications of such a view are considered, with special emphasis on methods seeking to enhance cross-modal connectivity between separate brain systems, including those using rhythmic and musical training in dyslexic patients.
在几十年前发表的一篇堪称经典的文章中（《大脑》，2000年；第123卷：2373 - 2399页），我提出了“诵读困难的扩展时间加工缺陷假说”，表明时间加工缺陷不仅可以解释诵读困难儿童中通常注意到的与语言相关的特性，还能解释与一般时间加工受损相关的更广泛的一系列症状。在本综述论文中，我将从新的临床视角重新审视这一“历史性”假说，这一视角包括共病这一核心但解释不足的概念，同时也重新审视最新的实验研究工作，主要聚焦于脑成像数据。首先，与日常临床实践一致，我提议区分三组未能学会阅读的儿童，他们出现的概率大致相同，有相同的初始表现（掌握字素 - 音素对应规则困难），但伴有不同的相关体征和/或共病情况（第一组为语言障碍，第二组为注意力缺陷，最后一组为运动协调问题），从而至少部分地表明潜在的触发机制可能不同。然后，根据目前可获得的脑成像信息表明，损害阅读技能习得的认知障碍的三种主要临床症状/关联对应于特定脑网络中三种不同的错误连接或“断开连接”模式，这些脑网络共同参与学习过程，并且严重依赖信息加工的时间特征。参照诵读困难的经典时间加工缺陷以及诵读困难大脑无法使振荡脑活动与外部事件的时间特征实现充分耦合的最新证据，提出了一个通用模型，根据该模型，各种断开连接和/或错误连接的处理器之间时间解耦的共同机制可能解释特定学习障碍的不同形式，阅读障碍或多或少是一个恒定特征。最后，考虑了这种观点的潜在治疗意义，特别强调旨在增强不同脑系统之间跨模态连接的方法，包括对诵读困难患者使用节奏和音乐训练的方法。
