fMRI abnormalities in dorsolateral prefrontal cortex during a working memory task in manic, euthymic and depressed...

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Psychiatry

Background:

• Neuropsychological studies indicate working memory deficits in bipolar disorder, persisting even during euthymic periods.
• Functional neural underpinnings of these impairments require further elucidation across various mood states.

Purpose of the Study:

• To investigate the functional neural basis of working memory impairments in bipolar disorder using fMRI.
• To compare brain activation patterns in working memory regions between bipolar subjects and controls across different mood states.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to assess brain activation during an n-back task.
• Participants included 42 bipolar subjects (manic, euthymic, depressed) and 14 healthy controls.
• Activation was evaluated in dorsolateral prefrontal cortex (BA9/46) and posterior parietal cortex (BA40).

Main Results:

• Bipolar subjects demonstrated similar task performance to controls.
• A significant reduction in activation was observed in right BA9/46 and right BA40 across all bipolar mood states.
• Attenuated neural activation in working memory circuits was evident, independent of mood state.

Conclusions:

• Bipolar disorder is associated with significantly reduced neural activation in core working memory circuits.
• This neural deficit appears to be a trait-related characteristic, persisting across mood states.
• Potential compensatory mechanisms involving other brain regions warrant further investigation.