CHARACTERIZING THREAT’S INFLUENCE IN POST-ENCODING REACTIVATION AND ITS DOWNSTREAM CONSEQUENCES ON MEMORY REPRESENTATIONS

Threatening events influence memory systems in complex ways. While it was once believed that emotion enhanced all aspects of memory, recent evidence suggests that it improves recall of emotional central features, but not neutral peripheral details (Payne & Kensinger, 2011). Other studies show that emotion can enhance context, retroactively benefiting related neutral events over time (Dunsmoor et al., 2015). Notably, both effects emerge after sleep, indicating a role for memory consolidation. Recently, Cowan et al. (2021) proposed that consolidation not only strengthens salient information but also adaptively transforms memories via semanticization and integration. In this dissertation, we adopt this adaptive memory framework to investigate behavioral and neural markers of threat memory transformation. First, using free recall changes over a week as a behavioral measure of memory transformation, we show that higher subjective arousal predicts greater semanticization, with fewer episodic details retained over time. Next, functional connectivity analyses reveal a division between anterior and posterior hippocampus: the posterior hippocampus, in conjunction with the basolateral amygdala and sensory cortex during encoding, is linked to less memory semanticization, while the anterior hippocampus, coupled with the lateral occipital cortex and precuneus during post-encoding, predicts greater semanticization. Moreover, representational similarity analyses reveal that long-term memory reinstatement is strongest in the precuneus, resembling early encoding patterns, with both hippocampal regions shifting over time towards gist representations, albeit with varying granularity. Finally, we report a negative relationship between neural reinstatement in the lateral occipital cortex and memory semanticization, suggesting that detailed cortical representations help preserve event details over time. These findings support the adaptive memory model (Cowan et al., 2021), emphasizing the dynamic roles of the hippocampus, amygdala and cortex in threat memory transformation.