In human subjects, reversal-learning performance is impaired in some substance-dependent individuals.73–75 These effects appear to be due, at least in part, to chronic exposure to drugs of abuse, because animal models exposed to drugs in either experimenter-delivered or self-administration paradigms exhibit reversal learning problems as a consequence.76–78 On the other hand, a recent study demonstrated that inbred strains of mice previously shown to exhibit the greatest difficulty inhibiting a response during reversal learning79 also showed the greatest propensity to self-administer cocaine, as compared to strains with relatively normal or good reversal-learning abilities.80
