EEG and fMRI evidence for autobiographical memory reactivation in empathy

Abstract

Empathy relies on the ability to mirror and to explicitly infer others' inner states. Theoretical accounts suggest that memories play a role in empathy, but direct evidence of reactivation of autobiographical memories (AM) in empathy is yet to be shown. We addressed this question in two experiments. In Experiment 1, electrophysiological activity (EEG) was recorded from 28 participants. Participants performed an empathy task in which targets for empathy were depicted in contexts for which participants either did or did not have an AM, followed by a task that explicitly required memory retrieval of the AM and non-AM contexts. The retrieval task was implemented to extract the neural fingerprints of AM and non-AM contexts, which were then used to probe data from the empathy task. An EEG pattern classifier was trained and tested across tasks and showed evidence for AM reactivation when participants were preparing their judgement in the empathy task. Participants self-reported higher empathy for people depicted in situations they had experienced themselves as compared to situations they had not experienced. A second independent fMRI experiment replicated this behavioural finding and showed increased activation for AM compared to non-AM in the brain networks underlying empathy: precuneus, posterior parietal cortex, superior and inferior parietal lobule, and superior frontal gyrus. Together, our study reports behavioural, electrophysiological, and fMRI evidence that robustly supports AM reactivation in empathy.

Keywords: EEG; EEG pattern classifier; autobiographical memory; empathy; fMRI.

FIGURE 1

Experimental design. (a) Schematic representation of the empathy task used in Experiments 1 and 2. Participants were required to rate how much empathy they felt for the person depicted in the preceding context. (b) Schematic representation of the retrieval task used in Experiment 1 that was used to train the linear discriminant analysis (LDA) classifier. Participants first learnt to associate four abstract figures with the same sentences describing painful contexts presented during the empathy task (not shown here). In the actual task, for each trial, participants were presented with one of the four figures and had to picture in their mind's eye the context that they learnt to associate with that specific figure. (c) Raincloud plots of the subjective reports of participants' empathy awareness in Experiments 1 and 2. (d) Concept of the study; when we encounter someone, who shares our same physically painful experience, the memory of that experience is reactivated to empathize

FIGURE 2

Event‐related potentials (ERPs) results. Left panel: ERPs time‐locked to the onset of the face and reflecting autobiographical memories (AM) and non‐AM at the anterior (upper panel) and the posterior cluster (bottom panel. Right top panel: clusters analysis performed over all the electrodes in a 0–1 s time‐window. Colours code t‐values. Right bottom panel: source localization of the AM versus non‐AM contrast

FIGURE 3

Linear discriminant analysis (LDA) results (a) Sanity check: time by time generalization matrix showing significant classification of autobiographical memories (AM) versus non‐Am within the retrieval task. (b) Time by time generalization matrix (i.e., training and testing at each time‐point) showing significant classification of AM versus non‐AM across tasks

FIGURE 4

fMRI results. whole‐brain analysis results (left panel) and raincloud plots (right panel) of the activation in each condition and each cluster. (a) Whole‐brain analysis related to the presentation of the context. Only the contrast autobiographical memories (AM) > non‐AM showed significant clusters. (b) Whole‐brain analysis related to the presentation of the face. Figure shows significant clusters resulting from both the AM > non‐AM and non‐AM > AM contrasts