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Altered effective connectivity during working memory performance in schizophrenia: a study with fMRI and structural
Ralf Schlösser1, Thomas Gesierich, Bettina Kaufmann
1Department of Psychiatry, University of Mainz, Mainz, Germany. Ralf.Schloesser@uni-jena.de
Neuroimage
|July 26, 2003
Summary
Schizophrenia patients show altered brain connectivity during working memory tasks, with reduced prefrontal-cerebellar connections but increased thalamo-cortical pathways. These findings highlight complex network changes in schizophrenia.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Psychiatry
Background:
- Schizophrenia is associated with cognitive deficits, including working memory impairments.
- Altered functional connectivity in brain networks is a key hypothesis in schizophrenia pathophysiology.
- Understanding these network alterations is crucial for developing targeted treatments.
Purpose of the Study:
- To investigate differences in effective connectivity within a cortical-subcortical-cerebellar network during a 2-back working memory task in patients with schizophrenia compared to healthy controls.
- To examine how antipsychotic treatment (typical vs. atypical) influences effective connectivity in schizophrenia patients.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to study 12 schizophrenic patients and 6 healthy controls performing a 2-back task.
- Structural equation modeling (SEM) was applied to assess effective connectivity within a network including prefrontal cortex, parietal cortex, thalamus, and cerebellum.
- Group differences in connectivity patterns were analyzed, with specific attention to treatment effects.
Main Results:
- Schizophrenia patients exhibited reduced connectivity in the prefrontal-cerebellar and cerebellar-thalamic pathways but enhanced connectivity in the thalamo-cortical pathway compared to controls.
- Patients treated with atypical antipsychotics showed enhanced interhemispheric connectivity but reduced right prefrontal and left parieto-frontal connectivity.
- Findings suggest a complex pattern of both increased and decreased connectivity, aligning with the concept of 'cognitive dysmetria' in schizophrenia.
Conclusions:
- The study reveals intricate alterations in effective connectivity within the cortical-subcortical-cerebellar network in schizophrenia.
- Enhanced thalamo-cortical connectivity may represent a compensatory mechanism for disrupted upstream pathways.
- SEM is a feasible method for investigating treatment-related connectivity differences in schizophrenia, offering insights into functional capacity and fMRI signal changes.