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

  1. Sagi Jaffe-Dax  Is a corresponding author
  2. Orr Frenkel
  3. Merav Ahissar  Is a corresponding author
  1. The Hebrew University of Jerusalem, Israel

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

  1. Sagi Jaffe-Dax

    Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
    For correspondence
    sagi.jaffe@mail.huji.ac.il
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8759-6980
  2. Orr Frenkel

    Psychology Department, The Hebrew University of Jerusalem, Jerusalem, Israel
    Competing interests
    The authors declare that no competing interests exist.
  3. Merav Ahissar

    Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
    For correspondence
    msmerava@gmail.com
    Competing interests
    The authors declare that no competing interests exist.

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.

Reviewing Editor

  1. Andrew J King, University of Oxford, United Kingdom

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.

Version history

  1. Received: August 12, 2016
  2. Accepted: January 9, 2017
  3. Accepted Manuscript published: January 24, 2017 (version 1)
  4. 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.

Metrics

  • 4,829
    Page views
  • 525
    Downloads
  • 30
    Citations

Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Sagi Jaffe-Dax
  2. Orr Frenkel
  3. Merav Ahissar
(2017)
Dyslexics' faster decay of implicit memory for sounds and words is manifested in their shorter neural adaptation
eLife 6:e20557.
https://doi.org/10.7554/eLife.20557

Share this article

https://doi.org/10.7554/eLife.20557

Further reading

    1. Neuroscience
    Katharina Eichler, Stefanie Hampel ... Andrew M Seeds
    Research Advance

    Mechanosensory neurons located across the body surface respond to tactile stimuli and elicit diverse behavioral responses, from relatively simple stimulus location-aimed movements to complex movement sequences. How mechanosensory neurons and their postsynaptic circuits influence such diverse behaviors remains unclear. We previously discovered that Drosophila perform a body location-prioritized grooming sequence when mechanosensory neurons at different locations on the head and body are simultaneously stimulated by dust (Hampel et al., 2017; Seeds et al., 2014). Here, we identify nearly all mechanosensory neurons on the Drosophila head that individually elicit aimed grooming of specific head locations, while collectively eliciting a whole head grooming sequence. Different tracing methods were used to reconstruct the projections of these neurons from different locations on the head to their distinct arborizations in the brain. This provides the first synaptic resolution somatotopic map of a head, and defines the parallel-projecting mechanosensory pathways that elicit head grooming.

    1. Neuroscience
    Songyao Zhang, Tuo Zhang ... Tianming Liu
    Research Article

    Cortical folding is an important feature of primate brains that plays a crucial role in various cognitive and behavioral processes. Extensive research has revealed both similarities and differences in folding morphology and brain function among primates including macaque and human. The folding morphology is the basis of brain function, making cross-species studies on folding morphology important for understanding brain function and species evolution. However, prior studies on cross-species folding morphology mainly focused on partial regions of the cortex instead of the entire brain. Previously, our research defined a whole-brain landmark based on folding morphology: the gyral peak. It was found to exist stably across individuals and ages in both human and macaque brains. Shared and unique gyral peaks in human and macaque are identified in this study, and their similarities and differences in spatial distribution, anatomical morphology, and functional connectivity were also dicussed.