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Optogenetic Entrainment of Hippocampal Theta Oscillations in Behaving Mice
Published on: June 29, 2018
Cross-region neuron co-firing mediated by ripple oscillations supports distributed working memory representations
Ilya A Verzhbinsky1,2, Jonathan Daume3, Sophia Cheng3
1Neurosciences Graduate Program, University of California San Diego, La Jolla, CA, USA. iverzhbi@health.ucsd.edu.
Nature Neuroscience
|August 12, 2026
Summary
High-frequency brain oscillations called ripples coordinate long-distance neural activity. These co-occurring ripples support working memory by synchronizing brain regions, even across large distances.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Systems Neuroscience
Background:
- High-frequency (~90-Hz) ripple oscillations are implicated in integrative processing in mammalian brains.
- Co-occurrence of ripples has been linked to enhanced temporal binding of neural activity in nearby cortical neurons.
- The role of ripple co-occurrence in supporting cognitive processing over greater distances remains unclear.
Purpose of the Study:
- To investigate whether co-ripple facilitation of neuronal coupling supports cognitive processing at greater distances.
- To analyze intracranial recordings during a working memory task to understand ripple dynamics across brain regions.
Main Methods:
- Intracranial recordings using microwire electrodes in human patients.
- Recordings were taken from the hippocampus, amygdala, ventromedial prefrontal cortex, anterior cingulate cortex, and pre-supplementary motor area.
- Analysis focused on ripple rates, co-occurrence, and cross-region co-firing during a working memory task.
Main Results:
- Ripple rates increased in all recorded regions during working memory encoding, maintenance, and retrieval.
- Inter-regional ripple co-occurrence increased, associated with ~30% increases in cross-region co-firing, without decrement over distances up to 220 mm.
- Cross-regional co-rippling and co-firing scaled with memory load and promoted reinstatement of stimulus-specific, long-distance co-firing patterns during retrieval.
Conclusions:
- Co-occurring ripple oscillations coordinate long-range, stimulus-specific neural co-firing.
- This coordination supports distributed neural representations essential for human cognition, particularly working memory.
- Ripple synchrony facilitates communication between distant brain regions, crucial for complex cognitive functions.
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