Interference with existing memories alters offline intrinsic functional brain connectivity

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Memory reconsolidation allows existing memories to be modified after reactivation.
• Previous research lacked evidence for intrinsic, systems-level signatures of offline memory modification.
• Motor memory systems, including corticostriatal pathways, are crucial for learning and recall.

Purpose of the Study:

• To investigate whether noninvasive brain stimulation can modulate intrinsic, task-free functional brain connectivity associated with reactivated motor memories.
• To determine if modulated functional connectivity predicts offline memory modification.
• To explore the specificity of stimulation effects on corticostriatal versus cerebellar pathways.

Main Methods:

• Behavioral experiments assessing motor memory strength.
• Noninvasive transcranial magnetic stimulation (TMS) applied during specific offline periods after memory reactivation.
• Functional magnetic resonance imaging (fMRI) to measure resting-state functional connectivity.
• Analysis of corticostriatal and cerebellar-cortical functional connectivity.

Main Results:

• TMS interference with reactivated motor memory reduced offline corticostriatal functional connectivity compared to control stimulation.
• The degree of functional connectivity reduction predicted the extent of offline memory modification.
• This reduction in connectivity was temporary, recovering after task re-execution, and did not affect cerebellar-cortical connectivity.

Conclusions:

• Intrinsic, task-free offline brain activity associated with memory can be modulated by noninvasive stimulation targeting reactivated memories.
• Modulation of corticostriatal functional connectivity is a systems-level signature of offline memory modification.
• These findings provide a neurophysiological basis for understanding how memories are updated during rest.