(1) Background—the magnocellular hypothesis proposes that impaired development of the visual timing systems in the brain that are mediated by magnocellular (M-) neurons is a major cause of dyslexia. Their function can now be assessed quite easily by analysing averaged visually evoked event-related potentials (VERPs) in the electroencephalogram (EEG). Such analysis might provide a useful, objective biomarker for diagnosing developmental dyslexia. (2) Methods—in adult dyslexics and normally reading controls, we recorded steady state VERPs, and their frequency content was computed using the fast Fourier transform. The visual stimulus was a black and white checker board whose checks reversed contrast every 100 ms. M- cells respond to this stimulus mainly at 10 Hz, whereas parvocells (P-) do so at 5 Hz. Left and right visual hemifields were stimulated separately in some subjects to see if there were latency differences between the M- inputs to the right vs. left hemispheres, and these were compared with the subjects’ handedness. (3) Results—Controls demonstrated a larger 10 Hz than 5 Hz fundamental peak in the spectra, whereas the dyslexics showed the reverse pattern. The ratio of subjects’ 10/5 Hz amplitudes predicted their reading ability. The latency of the 10 Hz peak was shorter during left than during right hemifield stimulation, and shorter in controls than in dyslexics. The latter correlated weakly with their handedness. (4) Conclusion—Steady state visual ERPs may conveniently be used to identify developmental dyslexia. However, due to the limited numbers of subjects in each sub-study, these results need confirmation.

中文翻译：

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发育障碍的视觉视觉细胞减少与事件相关的电位

（1）背景—精细胞假说提出，由精细胞（M-）神经元介导的大脑视觉定时系统发育受损是诵读困难的主要原因。现在，可以通过分析脑电图（EEG）中的平均视觉诱发事件相关电位（VERP）轻松评估其功能。此类分析可能为诊断发育困难的阅读器提供有用的，客观的生物标志物。（2）方法-在成人阅读障碍症患者和正常阅读控制中，我们记录了稳态VERP，并使用快速傅立叶变换计算了它们的频率含量。视觉刺激是黑白棋盘，每100毫秒检查一次反转对比度。M细胞主要在10 Hz对这种刺激做出反应，而细小细胞（P-）在5 Hz对这种刺激做出反应。在一些受试者中分别刺激左右视觉半视野，以查看在右半球和左半球的M-输入之间是否存在潜伏期差异，并将其与受试者的惯性比较。（3）结果-对照在光谱中显示出比5 Hz的基本峰大10 Hz，而阅读困难的人则表现出相反的规律。受试者的10/5 Hz振幅比可预测其阅读能力。10 Hz峰值的潜伏期在左侧比在右侧半场刺激期间短，并且在对照组中比在阅读障碍症患者中短。后者与他们的惯性之间存在弱关联。（4）结论—稳定状态的可视化ERP可以方便地用于识别发展性阅读障碍。但是，由于每个子研究中的科目数量有限，因此需要对这些结果进行确认。