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Selective enhancement of low-gamma activity by tACS improves phonemic processing and reading accuracy in dyslexia.

  • Marchesotti S Department of Neuroscience, University of Geneva, Geneva, Switzerland.
  • Nicolle J Department of Neuroscience, University of Geneva, Geneva, Switzerland.
  • Merlet I Univ Rennes, Inserm, LTSI, UMR 1099, Rennes, France.
  • Arnal LH Department of Neuroscience, University of Geneva, Geneva, Switzerland.
  • Donoghue JP Brown University, Providence, Rhode Island, United States of America.
  • Giraud AL Department of Neuroscience, University of Geneva, Geneva, Switzerland.
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  • 2020-09-08
Published in:
  • PLoS biology. - 2020
Adolescent
Adult
Auditory Cortex
Dyslexia
Electroencephalography
Evoked Potentials, Auditory
Female
Humans
Male
Middle Aged
Phonetics
Reading
Speech Perception
Transcranial Direct Current Stimulation
Verbal Behavior
Young Adult
English The phonological deficit in dyslexia is associated with altered low-gamma oscillatory function in left auditory cortex, but a causal relationship between oscillatory function and phonemic processing has never been established. After confirming a deficit at 30 Hz with electroencephalography (EEG), we applied 20 minutes of transcranial alternating current stimulation (tACS) to transiently restore this activity in adults with dyslexia. The intervention significantly improved phonological processing and reading accuracy as measured immediately after tACS. The effect occurred selectively for a 30-Hz stimulation in the dyslexia group. Importantly, we observed that the focal intervention over the left auditory cortex also decreased 30-Hz activity in the right superior temporal cortex, resulting in reinstating a left dominance for the oscillatory response. These findings establish a causal role of neural oscillations in phonological processing and offer solid neurophysiological grounds for a potential correction of low-gamma anomalies and for alleviating the phonological deficit in dyslexia.
Language
  • English
Open access status
gold
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Persistent URL
https://folia.unifr.ch/global/documents/233007
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