Fig. 2.

Behavioral dissociation of acquisition and expression. Mice were trained on an auditory go/no-go task in which they learn to lick to tone for a water reward (S+) and withhold licking to another tone to avoid a timeout (S-). Performance during learning in a reinforced context (top) has classically been equated to the ‘acquisition’ of task contingencies. In our data, we observe similar gradual acquisition trajectories in the reinforced context (top). We unmasked a more rapid acquisition trajectory by removing access to reinforcement in a few trials (bottom), and argue for a second dissociable process, ‘expression’, which reveals learned discriminations.