Semantic Representational Strength in the Precuneus and Lateral ATL Predicts Successful Factual Learning

Learning novel facts is central to modern life. While cortical regions involved in this process have been identified, the neural substrates underlying successful knowledge acquisition have remained elusive. In this fMRI study, we presented human participants (N = 29; 7, male) with a naturalistic learning task where 120 fictitious encyclopedic facts relating to people or places drawn from three imaginary civilizations. We then compared items that were subsequently recalled to those that were forgotten on a memory test that targeted associative learning, administered on average a day and a half later. To complement univariate analysis, we used multivariate pattern analysis to identify regions sensitive to semantic content during encoding, identifying medial precuneus, left angular gyrus, intraparietal sulcus, ventral occipitotemporal cortex, and the lateral anterior temporal lobes (latATL) bilaterally. Within these regions, the strength of informational content within the precuneus and left latATL predicted subsequent retrieval. In contrast, planned analyses did not find univariate differences between remembered and forgotten facts. Targeted follow-up region of interest analysis indicated a possible role of response magnitude in the left inferior frontal gyrus and no univariate or multivariate effects within medial temporal lobe structures. Collectively, these results support a model of fact learning predominantly driven by the richness of representations within semantic systems that is partially distinct from episodic learning mechanisms.