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Multi-timescale Rhythmic Dynamics in Rostral Ventromedial Medulla Neurons
Carl Ashworth1, Melissa Martenson2, Zhigang Shi2
1Computational and Biological Learning Lab, Department of Engineering, University of Cambridge, Cambridge, United Kingdom.
Biorxiv : the Preprint Server for Biology
|December 25, 2025
Summary
Brainstem neurons controlling pain integrate fast reflexes with slow state changes. This study reveals dual temporal dynamics in pain control circuits, impacting sensory modulation and internal state.
Area of Science:
- Neuroscience
- Pain research
- Systems neuroscience
Background:
- Neural circuits must balance rapid sensory reflexes with slower, state-dependent modulation.
- Pain control involves integrating fast withdrawal responses with dynamic changes in nociceptive sensitivity.
- The rostral ventromedial medulla (RVM) is a key brainstem center for descending pain modulation.
Purpose of the Study:
- To investigate the temporal dynamics of RVM neurons involved in pain control.
- To determine if RVM neurons operate across multiple timescales, integrating fast and slow processes.
- To explore the relationship between RVM neuronal activity, sensory modulation, and internal state.
Main Methods:
- Single-unit recordings from identified RVM ON-, OFF-, and NEUTRAL-cells in vivo.
- Probabilistic modeling, including Gaussian process models, to analyze neuronal activity.
- Analysis of stimulus-evoked responses and spontaneous rhythmic oscillations.
Main Results:
- RVM ON- and OFF-cells show multi-phase population responses with rapid activation and slow recovery (tens of seconds).
- These neurons exhibit slow, quasi-periodic oscillations (minutes) in the absence of stimulation.
- Rhythmic dynamics were specific to ON- and OFF-cells and showed coherence with autonomic parameters.
Conclusions:
- RVM neurons operate across multiple temporal scales, combining fast stimulus-evoked and slow intrinsic dynamics.
- A multi-timescale organizational principle governs descending brainstem pain control circuits.
- These dynamics jointly regulate sensory modulation and internal state control, potentially linking nociception and homeostasis.
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