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Blunted activation in orbitofrontal cortex during mania: a functional magnetic resonance imaging study
Lori L Altshuler1, Susan Y Bookheimer, Jennifer Townsend
1Department of Psychiatry, Los Angeles, California, USA. laltshuler@mednet.ucla.edu
Biological Psychiatry
|November 29, 2005
Summary
Bipolar mania is linked to reduced frontal lobe activity, specifically in the right lateral orbitofrontal cortex, during response inhibition tasks. This neural difference may explain manic disinhibition and requires further study.
Area of Science:
- Neuroscience
- Psychiatry
- Cognitive Neuroscience
Background:
- Abnormal cortical function is observed in patients during manic episodes.
- The lateral orbitofrontal cortex is crucial for response inhibition.
- Functional magnetic resonance imaging (fMRI) can investigate neural activity.
Purpose of the Study:
- To investigate frontal lobe neural activity during mania using fMRI.
- To evaluate activation in the lateral orbitofrontal cortex during a response inhibition task.
Main Methods:
- Eleven manic and 13 control subjects performed the Go-NoGo task during fMRI.
- Statistical parametric mapping was used to analyze whole-brain activation patterns.
- Contrasts between NoGo and Go conditions were analyzed.
Main Results:
- Control subjects showed robust activation in the right orbitofrontal cortex (BA 47).
- Manic subjects exhibited significantly reduced activation in the right lateral orbitofrontal cortex (BA 47), right hippocampus, and left cingulate (BA 24).
Conclusions:
- Mania is associated with attenuated activation in the right lateral orbitofrontal cortex.
- Reduced activation in this region may contribute to disinhibition symptoms observed in mania.
- Decreased hippocampal and cingulate activation also noted, warranting further exploration.