Reversal learning measurement
We next investigated the contribution of dopamine D2Rs to reversal learning behavior by inverting the reinforcement contingencies – now the former S+ signaled no reinforcer and the previous S- now indicated reinforcement availability. This manipulation permits an evaluation of the ability to inhibit responses to previously reinforced discriminative stimuli [18]. The number of trials necessary to establish 8 out of 10 accurate responses was our definition of successful reversal learning.