Dyslexics' faster decay of implicit memory for sounds and words is manifested in their shorter neural adaptation
Dyslexics' faster decay of implicit memory for sounds and words is manifested in their shorter neural adaptation
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DOI：
10.7554/elife.20557
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发表时间：
2017-01-30
期刊：
影响因子：
7.7
通讯作者：
Ahissar, Merav
中科院分区：
文献类型：
--
作者：
Jaffe-Dax, Sagi;Frenkel, Or;Ahissar, Merav
阅读障碍是一种普遍存在的阅读障碍，其潜在的机制仍存在争议。我们用一个简单的频率辨别任务研究了阅读困难的神经机制。虽然参与者被要求比较每个试验中的两个音调，但对之前试验的内隐记忆影响了他们的反应。我们假设内隐记忆在阅读困难者中衰退得更快。我们通过增加连续试验之间的时间间隔，以及测量来自听觉皮质的行为影响和事件相关电位反应来测试这一点。阅读困难症患者的内隐记忆效应在这两个指标上的衰减速度更快，时间常数相似。最后，内隐记忆的快速衰退也体现了语音规律对阅读障碍者口语阅读速度的影响。他们的受益随着时间间隔的变化而下降得更快，而不是之前阅读同一非单词的时间间隔。我们认为，阅读障碍者较短的神经适应时间矛盾地解释了他们较长的阅读时间，因为这减少了他们整合过去刺激的时间窗口，导致对简单和复杂刺激的更嘈杂和更不可靠的预测。不太可靠的预测限制了他们对阅读技能的获得。
Dyslexia is a prevalent reading disability whose underlying mechanisms are still disputed. We studied the neural mechanisms underlying dyslexia using a simple frequency-discrimination task. Though participants were asked to compare the two tones in each trial, implicit memory of previous trials affected their responses. We hypothesized that implicit memory decays faster among dyslexics. We tested this by increasing the temporal intervals between consecutive trials, and by measuring the behavioral impact and ERP responses from the auditory cortex. Dyslexics showed a faster decay of implicit memory effects on both measures, with similar time constants. Finally, faster decay of implicit memory also characterized the impact of sound regularities in benefitting dyslexics' oral reading rate. Their benefit decreased faster as a function of the time interval from the previous reading of the same non-word. We propose that dyslexics shorter neural adaptation paradoxically accounts for their longer reading times, since it reduces their temporal window of integration of past stimuli, resulting in noisier and less reliable predictions for both simple and complex stimuli. Less reliable predictions limit their acquisition of reading expertise.