McGovern Institute for Brain Research, Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, MA, 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, MA, 02139, USA; Program in Speech and Hearing Bioscience and Technology, Harvard University 260 Longwood Avenue, Boston, MA, 02115, USA.
Department of Speech, Language, and Hearing Sciences, Boston University 635 Commonwealth Avenue, Boston, MA, 02215, USA.
Neuropsychologia. 2022 Jan 28;165:108091. doi: 10.1016/j.neuropsychologia.2021.108091. Epub 2021 Nov 19.
A perceptual adaptation deficit often accompanies reading difficulty in dyslexia, manifesting in poor perceptual learning of consistent stimuli and reduced neurophysiological adaptation to stimulus repetition. However, it is not known how adaptation deficits relate to differences in feedforward or feedback processes in the brain. Here we used electroencephalography (EEG) to interrogate the feedforward and feedback contributions to neural adaptation as adults with and without dyslexia viewed pairs of faces and words in a paradigm that manipulated whether there was a high probability of stimulus repetition versus a high probability of stimulus change. We measured three neural dependent variables: expectation (the difference between prestimulus EEG power with and without the expectation of stimulus repetition), feedforward repetition (the difference between event-related potentials (ERPs) evoked by an expected change and an unexpected repetition), and feedback-mediated prediction error (the difference between ERPs evoked by an unexpected change and an expected repetition). Expectation significantly modulated prestimulus theta- and alpha-band EEG in both groups. Unexpected repetitions of words, but not faces, also led to significant feedforward repetition effects in the ERPs of both groups. However, neural prediction error when an unexpected change occurred instead of an expected repetition was significantly weaker in dyslexia than the control group for both faces and words. These results suggest that the neural and perceptual adaptation deficits observed in dyslexia reflect the failure to effectively integrate perceptual predictions with feedforward sensory processing. In addition to reducing perceptual efficiency, the attenuation of neural prediction error signals would also be deleterious to the wide range of perceptual and procedural learning abilities that are critical for developing accurate and fluent reading skills.
阅读障碍常伴有知觉适应缺陷，表现为对一致刺激的知觉学习能力差，对刺激重复的神经生理适应能力降低。然而，目前尚不清楚适应缺陷与大脑中前馈或反馈过程的差异有何关系。在这里，我们使用脑电图（EEG）来探究阅读障碍者和非阅读障碍者在观看面孔和单词对时的前馈和反馈对神经适应的贡献，该范式操纵了刺激重复的可能性高还是刺激变化的可能性高。我们测量了三个神经相关变量：期望（有和没有刺激重复期望的情况下，刺激前的 EEG 功率差异）、前馈重复（由预期变化和意外重复引起的事件相关电位（ERP）之间的差异）和反馈介导的预测误差（由意外变化和预期重复引起的 ERP 之间的差异）。期望在前馈和反馈过程中均显著调节了两组的刺激前θ波和α波 EEG。意想不到的单词重复，而不是面孔重复，也导致了两组 ERP 中显著的前馈重复效应。然而，与对照组相比，当意外变化而不是预期重复发生时，阅读障碍组的神经预测误差明显较弱，无论是面孔还是单词。这些结果表明，阅读障碍中观察到的神经和知觉适应缺陷反映了未能有效整合知觉预测与前馈感觉处理。除了降低知觉效率外，神经预测误差信号的衰减也会对广泛的知觉和程序性学习能力造成损害，这些能力对发展准确和流畅的阅读技能至关重要。
