The late positive potential (LPP) is a sustained positive deflection in the event-related potential that is larger following the presentation of emotional compared to neutral visual stimuli. Recent studies have indicated that the magnitude of the LPP is sensitive to emotion regulation strategies such as reappraisal, which involves generating an alternate interpretation of emotional stimuli so that they are less negative. It is unclear, however, whether reappraisal-related reductions in the LPP reflect reduced emotional processing or increased cognitive demands following reappraisal instructions. In the present study, we sought to examine whether a more or less negative description preceding the presentation of unpleasant images would similarly modulate the LPP. The LPP was recorded from 26 subjects as they viewed unpleasant and neutral International Affective Picture System images. All participants heard a brief description of the upcoming picture; prior to unpleasant images, this description was either more neutral or more negative. Following the more neutral description, the magnitude of the LPP, unpleasant ratings, and arousal ratings were all reliably reduced. These results indicate that changes in narrative are sufficient to modulate the electrocortical response to the initial viewing of emotional pictures, and are discussed in terms of recent studies on reappraisal and emotion regulation.

Consistent with the notion that emotional stimuli receive preferential attention and perceptual processing, many event-related potential (ERP) components appear sensitive to emotional stimuli. In an effort to differentiate components that are sensitive to emotional versus neutral stimuli, the current study utilized temporospatial principal components analysis to analyze ERPs from a large sample (N=82) while pleasant, neutral, and unpleasant images were passively viewed. Several factors sensitive to emotional stimuli were identified-corresponding to the N1, early posterior negativity (EPN), and P3; multiple factors resembling the late positive potential (LPP) emerged. Results indicate that the N1 represents the earliest component modulated by emotional stimuli; the EPN and the LPP represent unique components; the scalp-recorded LPP appears to include a P3-like positivity as well as additional positivities at occipital and central recording sites.

Event-related potential studies of reward processing have consistently identified the feedback negativity (FN), an early neural response that differentiates feedback indicating unfavorable versus favorable outcomes. Several important questions remain, however, about the nature of this response. In this study, the FN was recorded in response to monetary gains and losses during a laboratory gambling task, and temporospatial principal components analysis was used to separate the FN from overlapping responses. The FN was identified as a positive deflection at frontocentral recording sites that was enhanced for rewards compared with nonrewards. Furthermore, source localization techniques identified the striatum as a likely neural generator. These data indicate that this apparent FN reflects increased striatal activation in response to favorable outcomes that is reduced or absent for unfavorable outcomes, thereby providing unique information about the timing and nature of basal ganglia activity related to reward processing.

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