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An fMRI study of semantic processing in men with schizophrenia
M Kubicki1, R W McCarley, P G Nestor
1Clinical Neuroscience Division, Laboratory of Neuroscience, Boston VA Healthcare System-Brockton Division, Department of Psychiatry, Harvard Medical School, Brockton, MA 02301, USA. kubicki@bwh.harvard.edu
Neuroimage
|December 20, 2003
Summary
Schizophrenia disrupts brain activity in semantic processing. Patients show reduced left inferior prefrontal cortex activation and increased left superior temporal gyrus activation, impacting word meaning and thought disturbance.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Psychiatry
Background:
- Schizophrenia is characterized by thought disturbances.
- Understanding the neural underpinnings of these disturbances is crucial.
- Cognitive tasks can reveal functional brain differences.
Purpose of the Study:
- To investigate brain activation patterns in schizophrenia during semantic and non-semantic word processing.
- To compare functional magnetic resonance imaging (fMRI) activity between schizophrenic patients and healthy controls.
- To explore the neural basis of thought disorder in schizophrenia.
Main Methods:
- Used a visual levels of processing (LOP) task with semantic (abstract/concrete) and perceptual (font size) encoding conditions.
- Employed fMRI to measure brain activation in 9 schizophrenic and 9 control subjects.
- Assessed behavioral performance (recognition, reaction time) and repetition priming effects.
Main Results:
- Both groups exhibited a depth of processing effect in recognition.
- Control subjects showed increased left inferior prefrontal cortex (LIPC) activation for semantic encoding and repetition priming.
- Schizophrenic patients displayed reduced LIPC activation and increased left superior temporal gyrus activation for semantic encoding, lacking repetition priming effects.
Conclusions:
- Schizophrenia involves disrupted frontal-temporal network activity during semantic processing.
- LIPC underactivation and left superior temporal gyrus overactivation may underlie impaired word meaning processing in schizophrenia.
- These neural differences may contribute to the characteristic thought disturbances observed in the disorder.