Task-dependent activity and connectivity predict episodic memory network-based responses to brain stimulation in...

Area of Science:

• Neuroscience
• Cognitive Aging
• Brain Stimulation

Background:

• Episodic memory is crucial for cognitive aging.
• Transcranial magnetic stimulation (TMS) affects memory, but mechanisms are unclear.
• Investigating TMS effects in healthy elders is important.

Purpose of the Study:

• To assess the behavioral and functional effects of excitatory TMS in healthy older adults.
• To understand how TMS influences episodic memory and brain activity.

Main Methods:

• Used intermittent theta-burst stimulation (a TMS paradigm) on the left inferior frontal gyrus in 24 healthy elders.
• Evaluated episodic memory task performance and brain activity using pre- and post-fMRI scans.
• Assessed memory performance across two processing levels (shallow vs. deep encoding).

Main Results:

• TMS increased activity in prefrontal and cerebellum-occipital areas during deep encoding, not shallow encoding or rest.
• Observed task-dependent changes in connectivity between cerebellum-occipital and left inferior frontal regions during encoding.
• Found that TMS effects correlated with inter-individual changes in brain network connectivity.

Conclusions:

• The aged brain's response to TMS is state-dependent, influenced by task components.
• TMS effects are linked to individual differences in brain connectivity.
• Findings offer insights into brain network dynamics in aging and the utility of combined stimulation and behavioral approaches.