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Published on: July 2, 2013
Cortical speech envelope tracking reflects lesion-symptom profiles in post-stroke aphasia
Guangting Mai1,2, Emily Upton1, Timothy D Griffiths3,4
1Department of Language and Cognition, Psychology and Language Sciences, University College London, London WC1E 6AE, UK.
Brain Communications
|July 25, 2026
Summary
Neural speech tracking reveals how brain activity relates to understanding speech, especially in people with aphasia after stroke. Reduced tracking in temporal lobe damage suggests it’s crucial for speech comprehension.
Area of Science:
- Neuroscience
- Speech-Language Pathology
- Cognitive Science
Background:
- Comprehending connected speech is vital for communication but impaired in post-stroke aphasia.
- Understanding the neural basis of impaired speech listening is key for effective assessment and treatment.
- Neural speech tracking offers insights into naturalistic speech processing and its causal role in comprehension.
Purpose of the Study:
- To investigate neural speech tracking mechanisms in individuals with aphasia and their relationship to speech comprehension.
- To compare speech tracking abilities in individuals with temporal lobe lesions, frontal lobe lesions, and healthy controls.
- To determine how speech intelligibility and lesion location influence neural tracking of speech.
Main Methods:
- Electroencephalography (EEG) was used to record brain activity during story listening in three groups: temporal lobe aphasia, frontal lobe aphasia, and controls.
- Participants listened to stories presented at varying intelligibility levels (clear, unintelligible, and behaviorally matched low-intelligibility).
- Neural decoding and encoding analyses quantified speech tracking at theta (syllable) and delta (multi-syllable) rates, examining global and local brain responses.
Main Results:
- Individuals with temporal lobe lesions showed significantly impaired speech comprehension compared to frontal lobe and control groups.
- Speech intelligibility influenced delta-rate tracking (linked to higher-order processing) but not theta-rate tracking (sensory responses).
- Reduced neural tracking was observed in the temporal group, with theta tracking correlating with comprehension in a lesion-specific, inverted-U pattern across all participants.
Conclusions:
- Neural envelope tracking reflects both lesion profiles and symptom severity in aphasia.
- Theta-rate speech tracking is sensitive to lesion location and demonstrates a complex relationship with comprehension success.
- Speech tracking is a valuable tool for elucidating the neural mechanisms underlying speech comprehension deficits in aphasia.
