Dissociation Between Neuronal and Astrocytic Calcium Activity in Response to Locomotion in Mice

Area of Science:

• Neuroscience
• Cell Biology
• Systems Neuroscience

Background:

• Locomotion engages complex neural circuits.
• Astrocytes, glial cells, play crucial roles in brain function.
• Coordinated neuronal and astrocytic activity underlies brain processing.

Purpose of the Study:

• To investigate the dynamic calcium (Ca²⁺) responses of neurons and astrocytes during locomotion.
• To compare the temporal dynamics and refractoriness of astrocytic and neuronal Ca²⁺ signaling.
• To elucidate the functional implications of astrocytic Ca²⁺ integration and amplification.

Main Methods:

• In vivo calcium imaging of neurons and astrocytes in the mouse somatosensory cortex.
• Utilizing an airlifted platform for controlled locomotion in head-fixed mice.
• Analyzing Ca²⁺ signal propagation, timing, and response patterns to repeated locomotion episodes.

Main Results:

• Astrocytic Ca²⁺ activity significantly increased during locomotion, originating in distal processes and propagating to the soma.
• Astrocytic somata acted as integrators and amplifiers of Ca²⁺ signals, exhibiting oscillatory behavior.
• Neuronal Ca²⁺ ([Ca²⁺]_i) increased rapidly with locomotion onset, while astrocytic signals lagged by seconds.
• Astrocytes displayed significant refractoriness to a second bout of locomotion, unlike neurons.

Conclusions:

• Astrocytic Ca²⁺ signaling during locomotion is distinct from neuronal signaling, with delayed and refractory properties.
• Astrocytic Ca²⁺ dynamics likely involve intracellular stores, contributing to metabolic and homeostatic support.
• The findings highlight differential roles of neurons and astrocytes in processing motor-related brain activity.