Emotional modulation of alpha asymmetry in dysphoria: results from an emotional imagery task

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Studies on electroencephalographic (EEG) alpha band asymmetry at rest have reported that, compared to healthy controls, dysphoric and clinically depressed individuals often display relatively less left- than right-sided cortical activity at anterior scalp sites, and the opposite pattern at posterior scalp sites. It has also been shown that depression-related differences in alpha lateralization at anterior and posterior sites are more likely to emerge during emotional tasks and during visuospatial tasks, respectively, rather than during resting conditions. However, although it is the well-established that posterior cortical activity plays a key role also in emotional processing in healthy individuals, the influence of dysphoria on posterior alpha asymmetry sites during an emotional task has yet to be examined. To this end, dysphoric (n=23) and nondysphoric (n=24) individuals performed an emotional imagery task including pleasant, neutral, and unpleasant narratives. The group with, but not without, dysphoria showed reduced left relative to right cortical activity at anterior sites, irrespective of emotional condition. By contrast, at posterior sites, individuals with dysphoria showed reduced right relative to left parietal activity during unpleasant, but not pleasant and neutral, imagery condition compared to nondysphoric individuals. Results at anterior scalp sites provide further evidence for the presence of a stable pattern of reduced approach motivation in dysphoric individuals. The association between dysphoria and right relative to left parietal hypoactivation in response to unpleasant imagery suggests that dysphoric individuals are more likely to use state-dependent dysfunctional strategies to regulate negative emotions compared to nondysphoric individuals.