Knowledge acquisition during exam preparation improves memory and modulates memory formation

According to the schema-relatedness hypothesis, new experiences that make contact with existing schematic knowledge are more easily encoded and remembered than new experiences that do not. Here we investigate how real-life gains in schematic knowledge affect the neural correlates of episodic encoding, assessing medical students 3 months before and immediately after their final exams. Human participants were scanned with functional magnetic resonance imaging while encoding associative information that varied in relatedness to medical knowledge (face-diagnosis vs face-name pairs). As predicted, improvements in memory performance over time were greater for face-diagnosis pairs (high knowledge-relevance) than for face-name pairs (low knowledge-relevance). Improved memory for face-diagnosis pairs was associated with smaller subsequent memory effects in the anterior hippocampus, along with increased functional connectivity between the anterior hippocampus and left middle temporal gyrus, a region important for the retrieval of stored conceptual knowledge. The decrease in the anterior hippocampus subsequent memory effect correlated with knowledge accumulation, as independently assessed by a web-based learning platform with which participants studied for their final exam. These findings suggest that knowledge accumulation sculpts the neural networks associated with successful memory formation, and highlight close links between knowledge acquired during studying and basic neurocognitive processes that establish durable memories. SIGNIFICANCE STATEMENT: In a sample of medical students, we tracked knowledge accumulation via a web-based learning platform and investigated its effects on memory formation before and after participants' final medical exam. Knowledge accumulation led to significant gains in memory for knowledge-related events and predicted a selective decrease in hippocampal activation for successful memory formation. Furthermore, enhanced functional connectivity was found between hippocampus and semantic processing regions. These findings (1) demonstrate that knowledge facilitates binding in the hippocampus by enhancing its communication with the association cortices, (2) highlight close links between knowledge induced in the real world and basic neurocognitive processes that establish durable memories, and (3) exemplify the utility of combining laboratory-based cognitive neuroscience research with real-world educational technology for the study of memory.