Enhanced Primary Motor Cortex Astrocyte Calcium Signaling With Motor Learning

Astrocytes form an integral part of the nervous system and are proposed to modulate neuronal circuits and behavior. The motor cortex plays a key role in the planning and execution of voluntary movements and makes key contributions to motor skill learning. However, whether motor skill learning modulates astrocytic Ca²⁺ signaling in the primary motor cortex (M1) is not known. To understand the role of astrocytes in the M1, we first characterized the Ca²⁺ signaling properties in astrocyte subcompartments in awake mice. We found that the subcompartments exhibited different Ca²⁺ event properties during the no movement periods and locomotion. We then asked whether astrocytic Ca²⁺ signaling in M1 is modulated with the acquisition of a skilled forelimb reaching task. Astrocytes exhibited altered Ca²⁺ event properties at different stages of learning a forelimb reaching task, with early and transient increases in Ca²⁺ event amplitude being the most prominent. These results demonstrate for the first time that, in addition to previously described synaptic plasticity, astrocytic Ca²⁺ signaling is also modified with motor skill learning.