The role of the context in emotional memory

The emotional Context Maintenance and Retrieval Model (eCMR13) emphasises the pivotal influence of a retrieved context to account for the impact of emotion on memory enhancements. It argues that strong associations between emotional items and their encoding context are created, enabling an enhanced recall for these elements when the retrieval occurs in a context that presents similar features with the encoding one.

Similarly, one of the core symptom of posttraumatic stress disorder (PTSD) - involuntary memories of the trauma1- are triggered by external sensory stimuli and/or internal emotional states experienced during the traumatic event, and reencountered in a neutral context. They may stem from a particular encoding of emotional items compared to neutral ones, but the mechanisms leading to their development is not fully understood.

Nonetheless, the assumption that emotional items are strongly bound to their context is still debated4. The argument regarding contextual memory may stem from the notion of context: I propose to differentiate "source" and "temporal" contexts. The "source context" suggested by the eCMR implements the emotionality of the context13 and would be amygdala and insula-dependent2. In contrast, there is evidence that the "temporal" context is hippocampal-dependent7,12. Notably, whilst the eCMR argues that emotional items are strongly bound to their "source" context, it states that they are not bound particularly strongly to their "temporal" context13. Therefore, research demonstrating impaired contextual memory for emotional items may stem from a reduced "temporal" context for the emotional content, and not necessarily from the source context.

My PhD project firstly aims at investigating the influence of the "source" context on the emotional memory enhancement, within the context of the eCMR model. I hypothesize that when one is in a situation that induces a physiological state (characterizing the "source" context) similar to that of the encoding phase, one is more likely to recall the emotional content of the scene encoded.

My second aim is to investigate the role of the hippocampus in mediating the association of "temporal" context with emotional memory. I hypothesize that the hippocampus' activity will be reduced when encoding emotional content. In addition, if the behavioural results show a reduced performance for temporal contextual memory for the emotional material, it would suggest temporal memory is hippocampal-dependent.

Findings from this project would provide important insight into the differential role of two contexts in emotional memory, the different brain mechanisms mediating their influence, and as such a better understanding of intrusions emergence in PTSD.

METHODS AND TECHNIQUES
Stress manipulation. To induce an acute stress response, participants will complete the cold pressor test (CPT), representing the "source" context. It is a validated laboratory stressor that has been shown to increase levels of salivary cortisol8.
Magnetic resonance imaging. Participants will undergo high-resolution functional MRI scanning during the encoding task and the memory test.
Data analysis. Using ANOVAs, I will assess whether the group of participants that have completed the CPT at encoding and retrieval show enhanced memory compared to the group that did not complete the CPT and whether this memory enhancement occurs at the same level for emotional and neutral materials. I will also assess whether memory enhancement is found for the temporal contextual component of emotional memory.

To assess functional data, fMRI time series will be analysed using a general linear model (GLM) in which individual events will be modelled based on stimuli valence and stress manipulations.

TIMEFRAME
First year: Setting up the behavioural experiments, collecting data at a behavioural level.
Second year: Running the fMRI experiments, collecting brain imaging data.
Third year: Depending on