Dyslexics’ faster decay of implicit memory for sounds and words is manifested in their shorter neural adaptation

Sagi Jaffe-Dax*, Or Frenkel, Merav Ahissar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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 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.

Original languageEnglish
Article numbere20557
JournaleLife
Volume6
DOIs
StatePublished - 24 Jan 2017
Externally publishedYes

Funding

FundersFunder number
11 Merav Ahissar Gatsby Charitable Foundation Merav Ahissar German-Israeli Foundation for Scientific Research and Development
Centre Azrieli Foundation Merav Ahissar Israel Science Foundation
Canadian Institutes of Health Research
International Development Research Centre
Gatsby Charitable FoundationI-1303-105.4/2015
Israel Science Foundation2425/15, 616/11
Azrieli Foundation

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