Neural correlates of affective stimulus evaluation: a case-by-case analysis

A recent study provided first evidence that neural correlates of affective stimulus evaluation, that is, the early posterior negativity (EPN) and late positive potential (LPP), can be assessed at the individual case level. Expanding the case-by-case approach, the main aim of the present study was to explore the process of affective stimulus evaluation within the individual participant with respect to multiple emotional stimulus classes. Toward this end, each participant viewed separate blocks of low- and high-arousing pictures from behavior systems of predator fear, disease avoidance and sexual reproduction. Thirteen out of 16 participants showed larger EPN and LPP amplitudes for higher- than lower-arousing stimuli for all three behavior systems. Furthermore, rather than indicating a general lack of emotional modulation, cases of non-significant EPN (N = 3) and LPP (N = 2) tests in individual participants appeared to be specific to a single emotion category. Overall, assessing the emotional modulation of the EPN and LPP across multiple behavior systems strengthens the case-by-case approach regarding an effect that is ‘common to all’ as well as by differentiating non-significant effects within individuals in terms of a content-specific or general phenomenon. Implications for revealing a general principle of emotion functioning and biomarker development are discussed.