Medial prefrontal cortex and self-referential mental activity: relation to a default mode of brain function

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Imaging

Background:

• The medial prefrontal cortex (MPFC) exhibits high resting metabolic activity.
• MPFC activity decreases during goal-directed behaviors, suggesting a default brain function mode.
• MPFC regions are implicated in the neural basis of the self.

Purpose of the Study:

• To investigate the role of MPFC default state activity in self-referential processing.
• To differentiate the functions of dorsal and ventral MPFC.
• To explore the neurobiology of the self through default brain activity.

Main Methods:

• Functional magnetic resonance imaging (fMRI) study.
• Subjects performed self-referential (internally cued condition, ICC) and non-self-referential (externally cued condition, ECC) judgments.
• Judgments involved evaluating affectively normed pictures (pleasant/unpleasant vs. indoors/outdoors).

Main Results:

• The ICC was associated with increased activity in the dorsal MPFC.
• Both active task conditions showed decreased activity in the ventral MPFC.
• Dorsal MPFC activation correlated with self-referential mental activity.
• Ventral MPFC deactivation correlated with attentional demands and reduced emotional processing.

Conclusions:

• Dorsal and ventral MPFC are differentially modulated by attention-demanding and self-referential tasks.
• Self-referential mental activity is linked to dorsal MPFC increases.
• Ventral MPFC reductions reflect the attenuation of emotional processing during tasks.
• Default state activity in MPFC may represent self-referential and emotional processing.