EEG-correlates of emotional memory and seasonal symptoms

Abstract

The aim of this study was to investigate a potential all-year vulnerability of people with seasonal mood fluctuations. We compared behavioral and neurophysiological responses to emotional stimuli in summer between people who report seasonal symptoms in winter and those who do not. EEG was recorded in summer from 119 participants while they memorized 60 emotional pictures, balanced for valence and arousal. The Seasonal Pattern Assessment Questionnaire was used to determine seasonal symptoms. EEG power was analyzed in the alpha and gamma frequency bands and in early (50–150 ms) and late (300–400 ms) time-windows over frontal, temporal, and occipital sites. Positive pictures were more frequently recalled than negative and neutral pictures, and negative pictures were more frequently recalled than neutral pictures (p < 0.001), but memory performance did not interact with seasonality. EEG power was overall higher in participants without elevated levels of seasonal symptoms (p = 0.043). This group difference interacted with emotional valence (p = 0.037), region of interest (p = 0.003), hemispheric differences (p = 0.027), frequency band (0.032), and time-window (0.018). This differential pattern of activation while viewing emotional pictures suggests a difference in emotional processing between the groups. The absence of behavioral effects but presence of differences in EEG activity suggests an all-year-long difference in processing of emotional contents in people who experience seasonal symptoms in winter.