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Updated: Aug 24, 2025
Simultaneous Imaging of Microglial Dynamics and Neuronal Activity in Awake Mice
Published on: August 23, 2022
Sleep decreases neuronal activity control of microglial dynamics in mice
I Hristovska1,2, M Robert1,2,3, K Combet1,2
1INSERM U1314, CNRS UMR5284, MeLiS, Lyon, France.
Abstract:
Microglia, the brain-resident immune cells, are highly ramified with dynamic processes transiently contacting synapses. These contacts have been reported to be activity-dependent, but this has not been thoroughly studied yet, especially in physiological conditions. Here we investigate neuron-microglia contacts and microglia morphodynamics in mice in an activity-dependent context such as the vigilance states. We report that microglial morphodynamics and microglia-spine contacts are regulated by spontaneous and evoked neuronal activity. We also found that sleep modulates microglial morphodynamics through Cx3cr1 signaling. At the synaptic level, microglial processes are attracted towards active spines during wake, and this relationship is hindered during sleep. Finally, microglial contact increases spine activity, mainly during NREM sleep. Altogether, these results indicate that microglial function at synapses is dependent on neuronal activity and the vigilance states, providing evidence that microglia could be important for synaptic homeostasis and plasticity.
Insights
Microglia, the brain's immune cells, dynamically interact with synapses based on neuronal activity and sleep states. These interactions influence synaptic function and plasticity, highlighting microglia's role in brain health.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are brain-resident immune cells with dynamic processes that contact synapses.
- The activity-dependent nature of these neuron-microglia contacts, especially under physiological conditions, requires further investigation.
Purpose of the Study:
- To investigate neuron-microglia contacts and microglia morphodynamics in mice.
- To explore the regulation of these interactions by neuronal activity and vigilance states (wake and sleep).
Main Methods:
- In vivo two-photon imaging in mice.
- Analysis of microglia morphodynamics and spine contacts.
- Investigation of Cx3cr1 signaling during sleep.
Main Results:
- Microglial morphodynamics and contacts with neuronal spines are regulated by both spontaneous and evoked neuronal activity.
- Sleep state modulates microglial dynamics via Cx3cr1 signaling.
- Microglial processes are drawn to active spines during wakefulness but less so during sleep; microglial contact enhances spine activity, particularly during NREM sleep.
Conclusions:
- Microglial synaptic function is dependent on neuronal activity and vigilance states.
- Microglia play a significant role in synaptic homeostasis and plasticity.
