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Utilizing Repetitive Transcranial Magnetic Stimulation to Improve Language Function in Stroke Patients with Chronic Non-fluent Aphasia
Published on: July 2, 2013
The right hemisphere supports but does not replace left hemisphere auditory function in patients with persisting
Sundeep Teki1, Gareth R Barnes, William D Penny
1Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, UK. sundeep.teki.10@ucl.ac.uk
Brain : a Journal of Neurology
|May 30, 2013
Summary
Stroke patients with speech comprehension deficits show altered brain connectivity in auditory processing networks. Their speech representations are less accurate, and they rely more on right-hemisphere regions, yet remain impaired.
Area of Science:
- Neuroscience
- Cognitive Science
- Speech Processing
Background:
- Auditory comprehension deficits following stroke, often associated with aphasia, significantly impact communication.
- Understanding the neural underpinnings of altered speech processing in these patients is crucial for developing targeted interventions.
Purpose of the Study:
- To investigate speech processing network connectivity in stroke patients with auditory comprehension deficits using magnetoencephalography (MEG).
- To compare brain connectivity patterns between stroke patients (aphasics) and age-matched controls in response to phonemic and acoustic stimuli.
Main Methods:
- Magnetoencephalography (MEG) and a mismatch paradigm were employed.
- Dynamic Causal Modelling (DCM) was used to probe connectivity within and between temporal lobes.
- Phonemic (different word) and acoustic (same word) oddballs served as stimuli.
Main Results:
- Control subjects exhibited stronger modulation of self-connections in the left primary auditory cortex and bilateral superior temporal gyrus based on phonemic differences.
- Aphasic patients showed altered connectivity, with stronger feed-forward connections from the right primary auditory cortex to the right superior temporal gyrus and interhemispheric connections from the left to right primary auditory cortex.
- Behavioral correlates in aphasics included negative correlation between phonemic perception and inter-hemispheric connectivity, and positive correlation between semantic performance and a feedback connection.
Conclusions:
- Aphasics with impaired speech comprehension demonstrate less veridical speech representations in both temporal lobes.
- These patients exhibit increased reliance on right hemisphere auditory regions, particularly the right superior temporal gyrus, for speech processing.
- Despite compensatory shifts in network connectivity, stroke patients with aphasia remain significantly impaired in speech comprehension.
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