Auditory aversive generalization learning prompts threat-specific changes in alpha-band activity.

Pairing a neutral stimulus with aversive outcomes prompts neurophysiological and autonomic changes in response to the conditioned stimulus (CS+), compared to cues that signal safety (CS-). One of these changes-selective amplitude reduction of parietal alpha-band oscillations-has been reliably linked to processing of visual CS+. It is, however, unclear to what extent auditory conditioned cues prompt similar changes, how these changes evolve as learning progresses, and how alpha reduction in the auditory domain generalizes to similar stimuli. To address these questions, 55 participants listened to three sine wave tones, with either the highest or lowest pitch (CS+) being associated with a noxious white noise burst. A threat-specific (CS+) reduction in occipital-parietal alpha-band power was observed similar to changes expected for visual stimuli. No evidence for aversive generalization to the tone most similar to the CS+ was observed in terms of alpha-band power changes, aversiveness ratings, or pupil dilation. By-trial analyses found that selective alpha-band changes continued to increase as aversive conditioning continued, beyond when participants reported awareness of the contingencies. The results support a theoretical model in which selective alpha power represents a cross-modal index of continuous aversive learning, accompanied by sustained sensory discrimination of conditioned threat from safety cues.

Moving toward reality: Electrocortical reactivity to naturalistic multimodal emotional videos.

While previous research has investigated the effects of emotional videos on peripheral physiological measures and conscious experience, this study extends the research to include electrocortical measures, specifically the steady-state visual-evoked potential (ssVEP). A carefully curated set of 45 videos, designed to represent a wide range of emotional and neutral content, were presented with a flickering border. The videos featured a continuous single-shot perspective, natural soundtrack, and excluded elements associated with professional films, to enhance realism. The results demonstrate a consistent reduction in ssVEP amplitude during emotional videos which strongly correlates with the rated emotional intensity of the clips. This suggests that narrative audiovisual stimuli have the potential to track dynamic emotional processing in the cortex, providing new avenues for research in affective neuroscience. The findings highlight the potential of using realistic video stimuli to investigate how the human brain processes emotional events in a paradigm that increases ecological validity. Future studies can further develop this paradigm by expanding the video set, targeting specific cortical networks, and manipulating narrative predictability. Overall, this study establishes a foundation for investigating emotional perception using realistic video stimuli and has the potential to expand our understanding of real-world emotional processing in the human brain.

Emotional Perception: Divergence of Early and Late Event-related Potential Modulation.

The early posterior negativity (EPN) is a mid-latency ERP component that is reliably enhanced by emotional cues, with a deflection beginning between 150 and 200 msec after stimulus onset. The brief, bilateral occipital EPN is followed by the centroparietal late positive potential (LPP), a long duration slow-wave that is strongly associated with emotional arousal ratings of scenes. A recent study suggests that the EPN is particularly sensitive to human bodies in scenes, independent of emotional intensity. Here, we directly investigate the influence of human body features on EPN modulation, using emotional and neutral scenes depicting people across a range of body exposures and orientations, in addition to scenes of pleasant, neutral, and unpleasant animals. The results demonstrate that the EPN is quite sensitive to human body features and weakly related to arousal ratings, whereas the LPP is strongly modulated by scenes that receive high arousal ratings. Based on these results and relevant work on body-specific visual perception, we speculate that modulation of the EPN may strongly reflect the early detection of human bodies, which serves as a predictor of emotional significance, whereas LPP modulation is more closely associated with the extended elaborative processing of scenes that are explicitly judged to be emotionally arousing.

A 5-min paradigm to evoke robust emotional reactivity in neuroimaging studies.

The advent of the Research Domain Criteria (RDoC) approach to funding translational neuroscience has highlighted a need for research that includes measures across multiple task types. However, the duration of any given experiment is quite limited, particularly in neuroimaging contexts, and therefore robust estimates of multiple behavioral domains are often difficult to achieve. Here we offer a "turn-key" emotion-evoking paradigm suitable for neuroimaging experiments that demonstrates strong effect sizes across widespread cortical and subcortical structures. This short series could be easily added to existing fMRI protocols, and yield a reliable estimate of emotional reactivity to complement research in other behavioral domains. This experimental adjunct could be used to enable an initial comparison of emotional modulation with the primary behavioral focus of an investigator's work, and potentially identify new relationships between domains of behavior that have not previously been recognized.

Do rare emotional scenes enhance LPP modulation?

The slow wave late positive potential (LPP) is one of the most dependable measures of emotional processing in human neuroscience. While LPP positivity shows modest malleability by emotional regulation and competing tasks, its fundamental enhancement by emotional scene perception is extremely reliable. Here we assess the impact of emotional scene frequency (67%, 50% and 17%) on the strength of LPP modulation, across 3 groups of participants, using consistent presentation and analysis methods. The results demonstrate strong consistency in the strength of emotional modulation across frequent, equiprobable, and rare emotion conditions. However, a small enhancement of LPP positivity was found during unpleasant scenes in the rare emotion condition. The LPP thus appears to be largely insensitive to contextual features such as scene frequency and predictability, suggesting that strong emotional cues persistently engage orienting and evaluation processes because this tendency was selected in phylogeny.

Humor and emotion: Quantitative meta analyses of functional neuroimaging studies.

Humor is a ubiquitous aspect of human behavior that is infrequently the focus of neuroscience research. To localize human brain structures associated with the experience of humor, we conducted quantitative activation likelihood estimate (ALE) meta analyses of 57 fMRI studies (n = 1248) reporting enhanced regional brain activity evoked by humorous cues versus matched control cues. We performed separate ALE analyses of studies that employed picture-driven, text-based, and auditory laughter cues to evoke humor. A primary finding was that complex humor activates supramodal areas of the brain strongly associated with emotional processes, including bilateral amygdala and inferior frontal gyrus. Moreover, activation in brain regions associated with language, semantic knowledge, and theory of mind were differentially modulated by text and picture-driven humor cues, while hearing laughter enhances activation in auditory association cortex. The identification of humor-driven brain networks has the potential to expand brain-derived models of human emotion and could provide useful targets in translational research and therapy.

Emotional and feature-based modulation of the early posterior negativity.

The early posterior negativity (EPN) has been shown to be enhanced by emotional relative to neutral scene perception. A subset of studies has also reported a bias in the EPN toward pleasant relative to unpleasant scenes. Functional MRI research has also identified a region in lateral occipital cortex that shows a sensitivity to the visual perception of body parts, which may contribute to the EPN. Here, we assess the roles of rated scene pleasantness and the depiction of body parts on modulation of the EPN in two studies, using scenes that are chosen to be of equivalent perceptual complexity. In Study 1, we presented two distinct highly pleasant and arousing scene contents (erotic couples and moments of jubilant victory) as well as neutral people, threat, and mutilation scenes. As in prior research, the EPN was enhanced by emotionally arousing scenes, with the greatest modulation evoked by erotic scenes, although victory scenes elicited stronger ratings of pleasantness and equivalent ratings of arousal. This result suggests that the EPN may be sensitive to distinct features found in erotic scenes. To determine the extent to which body part perception modulates the EPN, Study 2 compared EPN modulation evoked by erotic scenes with nonerotic nudist scenes. Ratings of pleasantness and arousal were reduced, yet nudist scenes led to stronger modulation of the EPN compared to erotic scenes. These data indicate that, in addition to the emotional intensity of scenes, modulation of the EPN may in part reflect the discrimination of unclothed body parts.

Photoperiodic Requirements for Induction and Maintenance of Rhythm Bifurcation and Extraordinary Entrainment in Male Mice.

Exposure of mice to a 24 h light:dark:light:dark (LDLD) cycle with dimly illuminated nights induces the circadian timing system to program two intervals of activity and two intervals of rest per 24 h cycle and subsequently allows entrainment to a variety of extraordinary light regimens including 30 h LDLD cycles. Little is known about critical lighting requirements to induce and maintain this non-standard entrainment pattern, termed "bifurcation," and to enhance the range of apparent entrainment. The current study determined the necessary duration of the photophase for animals to bifurcate and assessed whether requirements for maintenance differed from those for induction. An objective index of bifurcated entrainment varied with length of the photophase over 4-10 h durations, with highest values at 8 h. To assess photic requirements for the maintenance of bifurcation, mice from each group were subsequently exposed to the LDLD cycle with 4 h photophases. While insufficient to induce bifurcation, this photoperiod maintained bifurcation in mice transferred from inductive LDLD cycles. Entrainment to 30 h LDLD cycles also varied with photoperiod duration. These studies characterize non-invasive tools that reveal latent flexibility in the circadian control of rest/activity cycles with important translational potential for addressing needs of human shift-workers.