Exercise enhances hippocampal-cortical ripple interactions in the human brain

Area of Science:

• Neuroscience
• Cognitive Science
• Human Physiology

Background:

• Physical exercise is known to acutely improve hippocampus-dependent memory.
• While animal models explain cellular mechanisms, human studies highlight exercise's impact on hippocampal-cortical connectivity.
• The neurophysiological underpinnings of exercise-induced changes in these circuits remain unclear.

Purpose of the Study:

• To investigate the hypothesis that exercise modulates hippocampal-cortical ripple dynamics in the human brain.
• To explore the neurophysiological basis of exercise's short-term cognitive benefits.
• To examine changes in hippocampal sharp wave-ripples (SWRs) and their coupling with cortical networks following exercise.

Main Methods:

• Intracranial recordings were performed in epilepsy patients during resting state, before and after an exercise session.
• Analysis focused on hippocampal sharp wave-ripples (SWRs) and their synchronization with cortical activity.
• Heart rate was monitored to reflect exercise intensity.

Main Results:

• Exercise increased the rate of hippocampal ripples.
• Enhanced coupling and phase-synchrony were observed between cortical ripples (limbic, default mode networks) and hippocampal SWRs post-exercise.
• Higher exercise intensity (heart rate) correlated with increased resting-state ripples in specific cortical networks, including the default mode network.

Conclusions:

• A single exercise session directly alters ripple events, a key marker of memory processing.
• Exercise enhances the dynamic interplay between the hippocampus and cortical networks.
• These findings suggest that exercise-induced modulation of hippocampal ripples may underlie its acute cognitive benefits.