Dyslexics' faster decay of implicit memory for sounds and words is manifested in their shorter neural adaptation
Abstract
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 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 also characterized dyslexics' benefits in oral reading rate. It 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 induces noisier and less reliable predictions for both simple and complex stimuli.
Article and author information
Author details
Funding
Israel Science Foundation (616/11)
- Merav Ahissar
Israel Science Foundation (2425/15)
- Merav Ahissar
Gatsby Charitable Foundation
- Merav Ahissar
EPFL-HUJI collaboration
- Merav Ahissar
German-Israeli Foundation for Scientific Research and Development (I-1303-105.4/2015)
- Merav Ahissar
Canadian Institutes of Health Research
- Merav Ahissar
International Development Research Centre
- Merav Ahissar
Azrieli Foundation
- Merav Ahissar
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: Informed consent was acquired from all participants. The study was approved by The Hebrew University Committee for the Use of Human Subject in Research.
Reviewing Editor
- Andrew J King, University of Oxford, United Kingdom
Publication history
- Received: August 12, 2016
- Accepted: January 9, 2017
- Accepted Manuscript published: January 24, 2017 (version 1)
- Version of Record published: January 30, 2017 (version 2)
Copyright
© 2017, Jaffe-Dax et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Methods:
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Results:
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Conclusions:
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Funding:
Financial support for this work came from a Vanier Canada Graduate Scholarship from the Canadian Institutes of Health Research (G.I.G.), an Ontario Graduate Scholarship (S.S.), a Restracomp Research Fellowship provided by the Hospital for Sick Children (S.S.), an Institutional Research Chair in Neuroinformatics (M.D.), as well as a Natural Sciences and Engineering Research Council CREATE grant (M.D.).
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