Down but not out in posterior cingulate cortex: Deactivation yet functional coupling with prefrontal cortex during...

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• The posterior cingulate cortex (pCC) is known to deactivate during demanding cognitive tasks.
• Previous hypotheses suggested the pCC's role is limited to automatic memory retrieval due to weak correlations with cognitive control regions at rest.

Purpose of the Study:

• To investigate the functional coupling of the pCC during semantic decisions of varying difficulty.
• To test the hypothesis that the pCC supports both automatic and controlled memory processing by modulating its connectivity with executive control regions.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to examine the pCC's connectivity during easy and hard semantic decision tasks.
• Psychophysiological interaction (PPI) analysis was employed to assess task-dependent functional coupling.
• A second experiment correlated resting-state functional connectivity between the pCC and dorsolateral prefrontal cortex (PFC) with subsequent semantic task performance.

Main Results:

• The pCC showed expected deactivation with increasing task difficulty.
• Despite overall deactivation, the pCC exhibited increased functional connectivity with the dorsolateral PFC during harder semantic tasks compared to easier tasks and rest.
• Resting-state functional coupling between the pCC and dorsolateral PFC positively correlated with individual efficiency in semantic tasks.

Conclusions:

• Although the pCC's overall activity decreases during external tasks, its functional coupling with executive control regions like the dorsolateral PFC increases during goal-directed memory retrieval.
• These findings support a more dynamic role for the pCC, contributing to both automatic and controlled aspects of cognition.