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Abnormal processing of speech during oddball target detection in schizophrenia.
Elton T C Ngan1, Athena Vouloumanos, Tara A Cairo
1Department of Psychiatry, University of British Columbia, Vancouver, Canada. ngan@interchange.ubc.ca
Neuroimage
|October 22, 2003
Summary
Schizophrenia patients exhibit altered brain activity in speech processing regions, particularly in the right hemisphere. This abnormal functional lateralization of speech processing is linked to disorganized thinking severity in schizophrenia.
Area of Science:
- Neuroscience
- Psychiatry
- Cognitive Science
Background:
- Healthy individuals typically show left-dominant temporal lobe activation for speech sounds.
- Abnormal lateralization in temporal lobe speech-processing regions is a proposed hallmark of schizophrenia.
Purpose of the Study:
- To investigate hemispheric lateralization patterns in schizophrenia patients during speech versus nonspeech sound processing.
- To test if functional magnetic resonance imaging (fMRI) reveals abnormal lateralization in schizophrenia.
Main Methods:
- Event-related fMRI was employed in an auditory oddball task.
- Participants (14 schizophrenia patients, 29 healthy controls) detected speech and nonspeech sounds.
- Differential brain activation between speech and nonspeech stimuli was analyzed.
Main Results:
- Schizophrenia patients displayed greater differential activation for speech vs. nonspeech in the right temporal cortex and left temporal-parietal junction compared to controls.
- Increased activation in the left temporal-parietal junction correlated significantly with disorganized thinking severity.
- Abnormalities were also observed in the left superior frontal cortex.
Conclusions:
- Findings support the hypothesis of aberrant functional lateralization in speech processing in schizophrenia.
- The degree of disturbance in speech-processing circuits may correlate with the severity of disorganized thinking in schizophrenia.