Memory integration

The aim of this thesis was to characterize the neural mechanisms underlying memory integration. In chapter 2, we studied the neural underpinnings of regularity extraction across hippocampus-dependent episodic memories. We found higher connectivity between the hippocampus and the mPFC for the retrieval of items that were congruent to the regularity structure than for the items that were incongruent to it. Moreover, we also found increased cortico-cortical connectivity for the items that were congruent as compared with incongruent to the regularity structure. In chapter 3, we characterized the influence of time and sleep on the transformation from episodic to semantic memory. We found that regularity knowledge evolved in the first few hours post-encoding, as evidenced by an increase in generalization accuracy from immediately following encoding, to 4 hrs later. Whereas sleep and wakefulness did not differentially contribute to this increase, the amount of time spent in SWS correlated with generalization accuracy. In chapter 4 we investigated how a previously formed regularity structure, or schema, impacts new memory formation. Together, the behavioral and EEG results revealed that memory was inferior for schema-congruent items, leaving us to conclude that schemas have a strong impact on what is stored into memory. Finally, in chapter 5, we investigated the influence of acute emotional arousal and negative emotional traits on representational separation in the hippocampus. Results showed that acute emotional arousal increased representational separation in the hippocampus, whereas symptoms of affective pathology were instead related to a breakdown in representational separation