An adaptive memory system rarely learns information tabula rasa, but rather builds on prior knowledge to facilitate learning. How prior knowledge influences the neural representation of novel associations remains unknown. Here, participants associated pairs of faces in two conditions: a famous, highly familiar face with a novel face or two novel faces while undergoing fMRI. We examine multivoxel activity patterns corresponding to individual faces before and after learning. The activity patterns representing members of famous-novel pairs becomes separated in the hippocampus, that is, more distinct from one another through learning, in striking contrast to paired novel faces that become similar. In the left inferior frontal gyrus, however, prior knowledge leads to integration, and in a specific direction: the representation of the novel face becomes similar to that of the famous face after learning, suggesting assimilation of new into old memories. We propose that hippocampal separation might resolve interference between existing and newly learned information, allowing cortical assimilation. Thus, associative learning with versus without prior knowledge relies on radically different computations.
Bibliographical noteFunding Information:
This work was supported by Israel Science Foundation (150/16, to A.M.). We thank Haim Cohen and Alexa Tompary for facilitating the fMRI analyses and Maayan Trzewik for her help in data collection. We further thank Ram Frost, Alexa Tompary, David Clewett, Tarek Amer, Catherine Hartley, and Katherine Nussbaum for their insightful comments and suggestions in preparing the paper. We thank Danielle Babitz for her help in preparing the photos used in the paper.
© 2020, The Author(s).