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Brain activations in schizophrenia during a graded memory task studied with functional neuroimaging
P C Fletcher1, P J McKenna, C D Frith
1Wellcome Department of Cognitive Neurology, Institute of Neurology, London, England.
Archives of General Psychiatry
|November 18, 1998
Summary
Schizophrenia patients show impaired dorsolateral prefrontal cortex (DLPFC) activation during memory tasks, particularly when performance declines. Failures in other brain regions were independent of performance, suggesting core abnormalities.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Psychiatry
Background:
- Functional neuroimaging implicates prefrontal cortex (PFC) in memory.
- Schizophrenia studies often show reduced PFC activation.
- Dorsolateral PFC (DLPFC) dysfunction is a key area of interest.
Purpose of the Study:
- To investigate functional neuroanatomical differences between schizophrenia patients and controls.
- To characterize DLPFC activation patterns using a graded memory challenge.
- To assess group differences in relation to task performance.
Main Methods:
- Positron emission tomography (PET) was used to assess memory-related brain activity.
- Schizophrenia patients and age-matched controls performed a graded word list memory task.
- Analysis modeled linear and nonlinear effects of memory load on brain activation.
Main Results:
- Nonlinear group differences in DLPFC activation were observed.
- Controls showed increased DLPFC activation with higher memory load.
- Schizophrenia patients exhibited reduced DLPFC activation as memory load increased, correlating with performance.
- Schizophrenia patients failed to deactivate superior temporal and inferior parietal regions.
Conclusions:
- DLPFC activation deficits in schizophrenia are linked to performance levels.
- Failures in deactivation in other brain regions may represent core schizophrenia abnormalities.
- Task performance must be considered when analyzing DLPFC activation in schizophrenia.