Brain stimulation reduces dyslexia deficits

Date:
September 8, 2020
Source:
PLOS
Summary:
Restoring normal patterns of rhythmic neural activity through
non- invasive electrical stimulation of the brain alleviates
sound-processing deficits and improves reading accuracy in adults
with dyslexia, according to a new study.



FULL STORY ========================================================================== Restoring normal patterns of rhythmic neural activity through non-invasive electrical stimulation of the brain alleviates sound-processing deficits
and improves reading accuracy in adults with dyslexia, according to a
study published September 8, 2020 in the open-access journal PLOS Biology
by Silvia Marchesotti and Anne-Lise Giraud of the University of Geneva,
and colleagues.


========================================================================== Dyslexia is a frequent disorder of reading acquisition that affects up to
10% of the population, and is characterized by lifelong difficulties with written material. Although several possible causes have been proposed
for dyslexia, the predominant one is a phonological deficit, i.e., a
difficulty in processing language sounds. The phonological deficit in
dyslexia is associated with changes in rhythmic or repetitive patterns
of neural activity, specifically the so-called "low-gamma" (30-Hz) oscillations, in a sound-processing region of the brain called left
auditory cortex. But a causal relationship between these oscillations
and the ability to process phonemes had not been established in previous studies.

To address this question, the researchers applied transcranial alternating current stimulation (tACS) over left auditory cortex in 15 adults
with dyslexia and 15 fluent readers for a period of 20 minutes. This intervention immediately improved phonological processing and reading
accuracy in the dyslexia group, specifically when 30 Hz (but not 60 Hz) stimulation was used. Interestingly, the beneficial effect on phonological processing was most pronounced in those individuals who had poor reading skills, whereas a slightly disruptive effect was observed in very good
readers.

According to the authors, the results demonstrate for the first time the
causal role of low-gamma oscillatory activity in phonemic processing. The findings may pave the way to non-invasive therapeutic interventions aimed
at normalizing oscillatory function in auditory cortex and improving phonological processing in individuals with dyslexia.

Dr. Marchesotti adds: "The next steps for us are to investigate whether normalizing oscillatory function in very young children could have a long- lasting effect on the organization of the reading system, but also to
explore even less invasive means of correcting oscillatory activity for instance using neurofeedback training."

========================================================================== Story Source: Materials provided by PLOS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Silvia Marchesotti, Johanna Nicolle, Isabelle Merlet, Luc H. Arnal,
John
P. Donoghue, Anne-Lise Giraud. Selective enhancement of low-gamma
activity by tACS improves phonemic processing and reading accuracy
in dyslexia. PLOS Biology, 2020; 18 (9): e3000833 DOI: 10.1371/
journal.pbio.3000833 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200908142934.htm

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