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Effects of emotion and stress on mnemonic binding of contextual information: Brain dynamics and neural substrates

Subject Area General, Cognitive and Mathematical Psychology
Human Cognitive and Systems Neuroscience
Term from 2015 to 2020
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 283370187
 
Final Report Year 2020

Final Report Abstract

Emotional memories can be extremely robust and long-lasting, which in extreme circumstances can contribute to the development of mood, anxiety, and stress-related disorders. Despite abundant evidence showing enhanced memory for emotional aspects of events, less is known about the underlying mechanisms of memory for associated contextual information. This is of particular interest, because dysfunctional integration of item-context information in memory traces may play a critical role in the symptomatology of affective disturbances (e.g., intrusive memory reactivations in post-traumatic stress disorder, PTSD). In a series of event-related potential (ERP) and functional brain imaging (fMRI) experiments with healthy participants, we investigated temporal dynamics and neural substrates related to long-term item-context binding using neutral objects that were actively and passively associated with emotionally arousing or neutral scenes. Across studies, we reliably found that contextual memory tested after one week was enhanced for objects encoded with emotional scenes (emotional associates) compared to objects encoded with neutral scenes (neutral associates). We also found evidence that enhanced memory for emotional and neutral associates was mediated by distinct episodic memory representations (familiarity and recollection). Particularly, information about emotional associates with contextual details was recollection-based remembered and related to a pronounced parietal ERP old/new effect (around 500 ms) during retrieval, a putative correlate of recollection memory. In addition, enhanced functional activity was found during retrieval of objects from emotional scene contexts in brain regions previously linked to episodic memory and context retrieval (recollection), such as prefrontal cortex, parietal cortex and MTL (hippocampus, parahippcampal cortex). Further ERP results showed that enhanced retrieval of emotional associates is also triggered automatically (without explicit memory task) and that enhanced retrieval for emotional associates may result from heightened attention and elaborative processing during encoding (indexed by enhanced P100 and LPP amplitudes). The project also investigated the role of acute stress (also taking into account rapid and slow corticosteroid actions) on emotional and neutral item-context binding. Results are preliminary (elaborated analyses are currently in progress) but showed stress effects on context-binding in our paradigm. Contrary to our predictions that rapid cortisol would disrupt binding we found enhanced enhanced (but not diminished) MTL activity during retrieval of emotional associates, compared to controls. Furthermore, when slow cortisol actions were considered, we specifically found that acute stress applied 180 minutes before encoding result in a familiarity-based memory for emotional context information (parietal ERP old/new effect was also absent), which could be interpreted as impaired contextual memory binding. The results may give support for recent models suggesting that rapid stress (via catecholamine and non-genomic cortisol action) facilitates encoding (and later retrieval) of prioritized information. Slower longlasting genomic cortisol actions, on the other hand, may facilitate restorative processes, which includes diminished acquirement of new recollective information to promote undisturbed processing of prior experiences. Taken together, the project provided new neuroscientific insights into the binding mechanisms of emotional and neutral context information, which could also be relevant in understanding mechanisms, e.g. involved in the activation of trauma-related memories by neutral environmental cues in clinical disorders.

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