Dissociable roles of default-mode regions during episodic encoding.

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• The default-mode network (DMN) is implicated in various cognitive functions, including memory.
• Understanding the specific roles of DMN subregions during memory encoding is crucial.

Purpose of the Study:

• To investigate the differential roles of DMN regions during memory encoding using functional magnetic resonance imaging (fMRI).
• To examine how self-referential (pleasantness) versus semantic (man-made/natural) processing strategies affect memory encoding and DMN activity.
• To assess the impact of task-unrelated thoughts (TUT) on memory encoding and DMN function.

Main Methods:

• fMRI was used to monitor brain activity in participants encoding words using either pleasantness or man-made/natural tasks.
• Thought probes assessed task engagement versus task-unrelated thoughts (TUT) during encoding.
• A source retrieval task evaluated memory accuracy after the scanning session.

Main Results:

• Higher source retrieval accuracy was observed for words encoded using the pleasantness task compared to the man-made/natural task.
• Activity in left anterior medial PFC and left angular gyrus correlated with successful encoding across both tasks.
• Specific DMN regions showed differential activation patterns related to encoding success, task type, and the presence of TUT.

Conclusions:

• DMN regions exhibit dissociable roles in memory formation.
• The relationship between DMN activity and subsequent memory is influenced by encoding strategy and attentional state.
• Self-referential processing may facilitate memory encoding more effectively than semantic processing, potentially by modulating DMN activity.