Fueling Speech: The Role of Reward in Word Learning

Pablo Ripollés

Cognition and Brain Plasticity Unit, University of Barcelona

Little is known about the neurobiological mechanisms subserving memory formation when learning is not driven by explicit/external rewards or feedback, but rather by intrinsic monitoring of correct performance. Here, participants, which were engaged in a learning task in which no external reward/feedback was provided, exhibited enhanced fMRI-signals within the dopaminergic midbrain, hippocampus, and ventral striatum (the SN/VTA-Hippocampal loop) when successfully learning the meaning of new words. Importantly, new words that were better remembered showed increased activation and enhanced functional connectivity between the midbrain, hippocampus, and ventral striatum. Moreover, in two follow-up experiments, new words which were remembered after 24 hours were associated with higher subjective pleasantness ratings and increased activation in emotion related physiological measures during encoding. These results suggest that intrinsic reward related processes which are triggered by learning success can promote the storage of new information into long-term memory through the activation of the SN/VTA-Hippocampal loop, possibly via dopaminergic modulation of the midbrain.