Stimulating the hippocampal posterior-medial network enhances task-dependent connectivity and memory

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Episodic memory relies on dynamic activity in distributed hippocampal networks, specifically the posterior-medial network (PMN) and anterior-temporal network (ATN).
• Understanding how to modulate hippocampal network connectivity is crucial for enhancing memory function.

Purpose of the Study:

• To investigate if noninvasive stimulation can enhance task-dependent functional connectivity within hippocampal networks.
• To determine if enhanced connectivity predicts improvements in episodic memory.

Main Methods:

• Participants received noninvasive stimulation targeting the PMN or a control location.
• Functional magnetic resonance imaging (fMRI) was used to measure connectivity within the PMN and ATN during an autobiographical retrieval task and rest.
• Performance on a separate episodic memory test was assessed.

Main Results:

• PMN-targeted stimulation significantly increased functional connectivity within the PMN during autobiographical retrieval compared to rest.
• This enhancement was specific to the PMN and the task condition, not observed in the ATN or with control stimulation.
• Task-dependent increases in medial temporal lobe connectivity predicted improved episodic memory performance.

Conclusions:

• Noninvasive stimulation can effectively enhance task-dependent regulation of hippocampal network connectivity.
• Modulating hippocampal connectivity through stimulation is a viable strategy for improving episodic memory.