Neural coding of reward.

<p><b>(A, B)</b> Example neurons from PMd and M1 showing reward modulation that persisted after controlling for kinematic differences between rewarded and unrewarded trials (see Fig A in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0160851#pone.0160851.s001" target="_blank">S1 File</a>). Error bars show standard errors (SEMs) across trials. Vertical dashed line at zero indicates the time of reward. <b>(C, D)</b> Trial-averaged, population-averaged normalized firing rates (mean ± SEMs across neurons) for PMd and M1 from two monkeys. For each session, significant differences between rewarded and unrewarded peak PSTH amplitudes are indicated using an asterisk. PMd shows a clear increase after unrewarded trials compared to kinematically-matched rewarded trials.