Episodic Memory Encoding Interferes with Reward Learning and Decreases Striatal Prediction Errors

Description: [Wimmer, Braun, Daw, Shohamy (2014) J Neurosci] Group-level SPM for the contrasts: 1) Reward prediction error, 2) Reward prediction error modulation by memory encoding, 3) PPI of successful vs. unsuccessful memory formation. We sought to understand the nature of the interaction between incremental reward learning and concurrent episodic memory encoding. During the experiment, human participants made choices between two options (colored squares), each associated with a drifting probability of reward, with the goal of earning as much money as possible. Incidental, trial-unique object pictures, unrelated to the choice, were overlaid on each option. We found that better episodic memory was related to a decreased influence of recent reward experience on choice, both within and across participants. fMRI analyses further revealed that during learning the canonical striatal reward prediction error signal was significantly weaker when episodic memory was stronger. This decrease in reward prediction error signals in the striatum was associated with enhanced functional connectivity between the hippocampus and striatum at the time of choice.

Related article: http://doi.org/10.1523/JNEUROSCI.0204-14.2014