Coordinated yet asymmetric striatal neuromodulatory dynamics encode associative learning.

The striatum integrates dopamine and acetylcholine to support learning and behavioral flexibility, yet how these neuromodulators coordinate during associative learning remains unclear. Using longitudinal dual-color fiber photometry in mice, we simultaneously tracked both signals in the anterior dorsolateral striatum throughout Pavlovian conditioning. We find that learning recruits distinct forms of neuromodulatory plasticity: dopamine maintains rapid, contingency-dependent cue responses, whereas acetylcholine undergoes broader reorganization across training. Despite these differences, trial-by-trial covariance between the two signals converges onto a compact low-dimensional structure that reliably captures learned behavioral state and distinguishes associative learning from sensory exposure alone. Granger causality analyses further reveal a directional asymmetry, present in both paired and unpaired mice, whereby dopamine reliably predicts subsequent acetylcholine fluctuations, with only weak reciprocal prediction. Together, our results identify a low-dimensional organizational principle for dopamine-acetylcholine interactions, and suggest that dopamine acts as a leading temporal signal that shapes cholinergic dynamics during striatal learning.