Atypical low-frequency cortical encoding of speech identifies children with developmental dyslexia

Area of Science:

• Neuroscience
• Developmental Psychology
• Speech-Language Pathology

Background:

• Slow cortical oscillations are vital for processing the speech amplitude envelope.
• Children with developmental dyslexia exhibit atypical perception of speech amplitude envelope.
• Understanding the neural basis of speech processing in dyslexia is crucial for developing targeted interventions.

Purpose of the Study:

• To identify neural processing patterns involving slow oscillations in children with dyslexia using electroencephalography (EEG).
• To investigate if specific EEG patterns during natural speech listening can characterize children with dyslexia.
• To explore the potential of these neural patterns as biomarkers for dyslexia.

Main Methods:

• EEG was recorded from children during a natural speech listening (story) paradigm.
• Analysis focused on power dynamics and phase-amplitude coupling between delta and theta oscillations.
• Common Spatial Patterns (CSP) were isolated to identify dyslexic children, and a linear classifier was trained.

Main Results:

• Atypical power dynamics and phase-amplitude coupling between delta and theta oscillations differentiated dyslexic children from control groups.
• EEG common spatial patterns (CSP) in the delta band effectively identified dyslexic children (0.77 AUC).
• The identified spatial patterns were transferable to a rhythmic syllable processing task, suggesting a core deficit in speech rhythm processing.

Conclusions:

• Distinct atypical neurocognitive speech encoding mechanisms underlie dyslexia.
• The findings suggest a fundamental deficit in the neural processing of speech rhythm in children with dyslexia.
• These identified neural markers could inform the development of novel interventions for dyslexia.