THE DYNAMICS OF AUDITORY CORTICAL ASTROCYTES DURING SENSORIMOTOR LEARNING

Astrocytes are becoming increasingly recognized as active contributors to neural information processing, yet how their dynamics evolve during learning remains unclear. We used chronic fiber photometry and two-photon calcium imaging to longitudinally track astrocyte Ca²⁺ activity in the auditory cortex of awake mice expressing Aldh1l1-dependent GCaMP6s during acquisition of an auditory discrimination task. Mice learned to lick to a rewarded tone (S+) and withhold licking to an unrewarded tone (S−), with block-wise reward contingency shifts introduced via catch trials. Astrocytes exhibited rapid, learning-related modulation of Ca²⁺ activity, with enhanced responses during rewarded trials emerging within the first ~100 trials. This effect was not driven purely by licking, as astrocyte activity was suppressed during actively licking to the wrong tone (false alarms). Astrocyte responses unfolded on two timescales: an early, trial-locked component aligned with tone onset and initial licking, and a later, broader component of larger magnitude, likely related to reward or post-reward processing. Reward omission on correct trials produced biphasic responses where a transient increase in activity was followed by a profound suppression, suggesting that reward consumption may drive extended increases in astrocyte activity. Receiving extra reward amount (2x), led to a potentiation of these responses. Similar patterns were observed during correct reject trials in reward-shift blocks, even without licking. Baseline astrocyte activity reliably tracked reward context across trials. Together, these data indicate that astrocytes encode an abstract reward-context signal independent of movement, potentially supporting learning by integrating sensory and reward information across trial and inter-trial timescales.