Default network activation during episodic and semantic memory retrieval: A selective meta-analytic comparison.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroimaging

Background:

• The precise overlap and separation of default network subregions in episodic memory (EM) and semantic memory (SM) remain unclear.
• Task paradigms for EM and SM vary significantly in their default network engagement, necessitating controlled analysis.

Purpose of the Study:

• To investigate the extent of overlap and separation between default network subregions engaged in EM and SM retrieval.
• To control for variations in default network involvement across different EM and SM task paradigms.

Main Methods:

• A two-stage controlled meta-analysis of functional neuroimaging studies in healthy participants.
• Preliminary meta-analysis to identify EM and SM tasks with substantial default network recruitment.
• Main analysis comparing selected task paradigms for default network subregion engagement.

Main Results:

• Within EM tasks, the default network showed greater involvement in recollection/familiarity than old/new effects.
• Within SM tasks, the default network was more engaged in word/pseudoword than semantic/phonological effects.
• Direct comparison revealed significant overlaps in default network regions for EM and SM, including posterior cingulate/retrosplenial cortex, left inferior parietal lobule, and left anteromedial prefrontal cortex.

Conclusions:

• Episodic and semantic memory retrieval, particularly with strong memory signals, recruit extensive and overlapping default network regions.
• The primary distinction lies in the unique contribution of the hippocampal formation and parahippocampal cortex to EM retrieval processes.