Establishing a probabilistic reversal learning test in mice: Evidence for the processes mediating reward-stay and punishment-shift behaviour and for their modulation by serotonin

► Depressed patients exhibit deficits in probabilistic reversal learning (PRL). ► A PRL paradigm was developed for C57BL/6 mice. ► Operant responding was sensitive to probability of punished correct responses (PCR). ► Heterozygous serotonin transporter mutant mice exhibited reduced sensitivity to PCR. ► Low-acute SSRI escitalopram administration also reduced sensitivity to PCR.