Parallel contributions of distinct human memory systems during probabilistic learning

►Participants completed a feedback and observation probability learning task. ►The striatum and hippocampus were active during both types of probability learning. ►Activity in the ROIs was modulated by cue difficulty (probability of the outcome). ►Granger causality maps showed the two ROIs' activity was functionally connected. ►The striatum and hippocampus correlated with a feedback reward prediction error.