Abstract
Two-photon imaging is a powerful tool used to examine molecular and cellular functions in living tissues. In particular, calcium imaging can quantitatively measure neuronal activity i.e. action potential firing. Two-photon calcium imaging can detect the multicellular activity of neuronal circuits in the brain at the single cell level while animals perform behavioral tasks. Motor performance improves with repetitive training, and it has been proposed that this is mediated by functional and structural reorganization of the motor cortex. However, even without long-term training, animals can rapidly adapt to environmental change. To clarify how neuronal activities in the primary motor cortex (M1) are reorganized for long-lasting training and rapid adaptation, we conducted two-photon calcium imaging in the mouse M1 during 14-day training sessions of a self-initiated lever-pull task (Masamizu et al., Nat. Neurosci., 2014) and 15-min operant conditioning of single neurons (Hira et al., Nat. Commun., 2014), respectively. We found that the dynamics of neuronal activity during motor learning and fast neuronal operant conditioning depends on the layer structure and temporal timing of the activity.
