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.

Directional interconnectivity of the human amygdala, fusiform gyrus, and orbitofrontal cortex in emotional scene perception.

The perception of emotionally arousing scenes modulates neural activity in ventral visual areas via reentrant signals from the amygdala. The orbitofrontal cortex (OFC) shares dense interconnections with amygdala and has been strongly implicated in emotional stimulus processing in primates, but our understanding of the functional contribution of this region to emotional perception in humans is poorly defined. In this study we acquired targeted rapid functional imaging from lateral OFC, amygdala, and fusiform gyrus (FG) over multiple scanning sessions (resulting in over 1,000 trials per participant) in an effort to define the activation amplitude and directional connectivity among these regions during naturalistic scene perception. All regions of interest showed enhanced activation during emotionally arousing, compared with neutral scenes. In addition, we identified bidirectional connectivity between amygdala, FG, and OFC in the great majority of individual subjects, suggesting that human emotional perception is implemented in part via nonhierarchical causal interactions across these three regions.NEW & NOTEWORTHY Due to the practical limitations of noninvasive recording methodologies, there is a scarcity of data regarding the interactions of human amygdala and orbitofrontal cortex (OFC). Using rapid functional MRI sampling and directional connectivity, we found that the human amygdala influences emotional perception via distinct interactions with late-stage ventral visual cortex and OFC, in addition to distinct interactions between OFC and fusiform gyrus. Future efforts may leverage these patterns of directional connectivity to noninvasively distinguish clinical groups from controls with respect to network causal hierarchy.

Noninvasive stimulation of the ventromedial prefrontal cortex modulates emotional face processing.

The ventromedial prefrontal cortex (vmPFC) is associated with emotional states that can be characterized as positive affect. Moreover, a variety of psychiatric disorders that are associated with disturbed reactions toward reward- or safety-signaling stimuli reveal functional or structural anomalies within this area. Thus, neuromodulation of this region via transcranial direct current stimulation (tDCS) offers an attractive opportunity to noninvasively influence pleasant emotional and reward processing. Recent experiments revealed hemodynamic and electrophysiological evidence for valence specific modulations of emotional scene processing after excitatory and inhibitory tDCS of the vmPFC. Here, we identified that tDCS modulation of vmPFC during emotional face processing results in effects convergent with scene processing, in that excitatory tDCS increased neural reactivity during happy compared to fearful face perception, whereas inhibitory stimulation led to a converse effect. In addition, behavioral data (affect identification of ambiguous expressive faces) revealed a bias toward preferential processing of happy compared to fearful faces after excitatory compared to after inhibitory stimulation. These results further support the vmPFC as an appropriate target for noninvasive neuromodulation of an appetitive processing network in patients suffering from disturbed cognition of reward- and safety-signaling stimuli. It should however be noted that electrophysiological pre-tDCS differences at earlier time intervals of emotional face and scene processing appeared amplified by tDCS, which remains to be investigated.

Noninvasive Stimulation of the Ventromedial Prefrontal Cortex Enhances Pleasant Scene Processing.

Depressive patients typically show biased attention towards unpleasant and away from pleasant emotional material. Imaging studies suggest that dysfunctions in a distributed neural network, including the ventromedial prefrontal cortex (vmPFC), are associated with this processing bias. Accordingly, changes in vmPFC activation should mediate changes in processing of emotional stimuli. Here, we investigated the effect of inhibitory and excitatory transcranial direct current stimulation (tDCS) of the vmPFC on emotional scene processing in two within-subject experiments using functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). Both studies showed that excitatory relative to inhibitory tDCS amplifies processing of pleasant compared to unpleasant scenes in healthy participants. This modulatory effect occurred in a distributed network including sensory and prefrontal cortex regions and was visible during very early to late processing stages. Findings are discussed with regard to neurophysiological models of emotional processing. The convergence of stimulation effects across independent groups of healthy participants and complementary neuroimaging methods (fMRI, MEG) provides a basis for further investigation of a potentially therapeutic use of this novel stimulation approach in patients with depression or other affective disorders.

Sex differences in emotional perception: Meta analysis of divergent activation.

Behavioral and physiological sex differences in emotional reactivity are well documented, yet comparatively few neural differences have been identified. Here we apply quantitative activation likelihood estimation (ALE) meta-analysis across functional brain imaging studies that each reported clusters of activity differentiating men and women as they participated in emotion-evoking tasks in the visual modality. This approach requires the experimental paradigm to be balanced across the sexes, and thus may provide greater clarity than previous efforts. Results across 56 emotion-eliciting studies (n=1907) reveal distinct activation in the medial prefrontal cortex, anterior cingulate cortex, frontal pole, and mediodorsal nucleus of the thalamus in men relative to women. Women show distinct activation in bilateral amygdala, hippocampus, and regions of the dorsal midbrain including the periaqueductal gray/superior colliculus and locus coeruleus. While some clusters are consistent with prevailing perspectives on the foundations of sex differences in emotional reactivity, thalamic and brainstem regions have not previously been highlighted as sexually divergent. These data strongly support the need to include sex as a factor in functional brain imaging studies of emotion, and to extend our investigative focus beyond the cortex.

Emotional scenes elicit more pronounced self-reported emotional experience and greater EPN and LPP modulation when compared to emotional faces.

Emotional faces and scenes carry a wealth of overlapping and distinct perceptual information. Despite widespread use in the investigation of emotional perception, expressive face and evocative scene stimuli are rarely assessed in the same experiment. Here, we evaluated self-reports of arousal and pleasantness, as well as early and late event-related potentials (e.g., N170, early posterior negativity [EPN], late positive potential [LPP]) as subjects viewed neutral and emotional faces and scenes, including contents representing anger, fear, and joy. Results demonstrate that emotional scenes were rated as more evocative than emotional faces, as only scenes produced elevated self-reports of arousal. In addition, viewing scenes resulted in more extreme ratings of pleasantness (and unpleasantness) than did faces. EEG results indicate that both expressive faces and emotional scenes evoke enhanced negativity in the N170 component, while the EPN and LPP components show significantly enhanced modulation only by scene, relative to face stimuli. These data suggest that viewing emotional scenes results in a more pronounced emotional experience that is associated with reliable modulation of visual event-related potentials that are implicated in emotional circuits in the brain.

Axonal fiber terminations concentrate on gyri.

Convoluted cortical folding and neuronal wiring are 2 prominent attributes of the mammalian brain. However, the macroscale intrinsic relationship between these 2 general cross-species attributes, as well as the underlying principles that sculpt the architecture of the cerebral cortex, remains unclear. Here, we show that the axonal fibers connected to gyri are significantly denser than those connected to sulci. In human, chimpanzee, and macaque brains, a dominant fraction of axonal fibers were found to be connected to the gyri. This finding has been replicated in a range of mammalian brains via diffusion tensor imaging and high-angular resolution diffusion imaging. These results may have shed some lights on fundamental mechanisms for development and organization of the cerebral cortex, suggesting that axonal pushing is a mechanism of cortical folding.

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.

A pilot study to investigate the efficacy and tolerability of lesion network guided transcranial electrical stimulation in outpatients with psychosis spectrum illness.

BACKGROUND: Transcranial electrical stimulation (tES) may improve psychosis symptoms, but few investigations have targeted brain regions causally linked to psychosis symptoms. We implemented a novel montage targeting the extrastriate visual cortex (eVC) previously identified by lesion network mapping in the manifestation of visual hallucinations. OBJECTIVE: To determine if lesion network guided High Definition-tES (HD-tES) to the eVC is safe and efficacious in reducing symptoms related to psychosis. METHODS: We conducted a single-blind crossover pilot study (NCT04870710) in patients with psychosis spectrum disorders. Participants first received HD-tDCS (direct current), followed by 4 weeks of wash out, then 2 Hz HD-tACS (alternating current). Participants received 5 days of daily (2×20 min) stimulation bilaterally to the eVC. Primary outcomes included the Positive and Negative Syndrome Scale (PANSS), biological motion task, and Event Related Potentials (ERP) from a steady state visual evoked potential (SSVEP) paradigm. Secondary outcomes included the Montgomery-Asperg Depression Rating Scale, Global Assessment of Functioning (GAF), velocity discrimination and visual working memory task, and emotional ERP. RESULTS: HD-tDCS improved PANSS general psychopathology in the short-term (d=0.47; pfdr=0.03), with long-term improvements in general psychopathology (d=0.62; pfdr=0.05) and GAF (d=-0.56; pfdr=0.04) with HD-tACS. HD-tDCS reduced SSVEP P1 (d=0.25; pfdr=0.005), which correlated with general psychopathology (ß = 0.274, t = 3.59, p = 0.04). No significant differences in safety or tolerability measures were identified. CONCLUSION: Lesion network guided HD-tES to the eVC is a safe, efficacious, and promising approach for reducing general psychopathology via changes in neuroplasticity. These results highlight the need for larger clinical trials implementing novel targeting methodologies for the treatments of psychosis.

Efficacy and Tolerability of Lesion Network Guided Transcranial Electrical Stimulation in Outpatients with Psychosis Spectrum Illness: A Nonrandomized Controlled Trial.

Importance: Transcranial electrical stimulation (tES) may improve psychosis symptoms, but few investigations have targeted brain regions causally linked to psychosis symptoms. We implemented a novel montage targeting the extrastriate visual cortex (eVC) previously identified by lesion network mapping in the manifestation of visual hallucinations. Objective: To determine if lesion network guided HD-tES to the eVC is safe and efficacious in reducing symptoms related to psychosis. Design Setting and Participants: Single-center, nonrandomized, single-blind trial using a crossover design conducted in two 4-week phases beginning November 2020, and ending January 2022. Participants were adults 18-55 years of age with a diagnosis of schizophrenia, schizoaffective or psychotic bipolar disorder as confirmed by the Structured Clinical Interview for DSM-V, without an antipsychotic medication change for at least 4 weeks. A total of 8 participants consented and 6 participants enrolled. Significance threshold set to <0.1 due to small sample size. Interventions: 6 Participants first received HD-tDCS (direct current), followed by 4 weeks of wash out, then 4 received 2Hz HD-tACS (alternating current). Participants received 5 consecutive days of daily (2 × 20min) stimulation applied bilaterally to the eVC. Main Outcomes and Measures: Primary outcomes included the Positive and Negative Syndrome Scale (PANSS) total, positive, negative, and general scores, biological motion task, and Event Related Potential (ERP) measures obtained from a steady state visual evoked potential (SSVEP) task across each 4-week phase. Secondary outcomes included the Montgomery-Asperg Depression Rating Scale (MADRS), Global Assessment of Functioning (GAF), velocity discrimination task, visual working memory task, and emotional ERP across each 4-week phase. Results: HD-tDCS improved general psychopathology in the short-term (d=0.47; p fdr =0.03), with long-term improvements in general psychopathology (d=0.62; p fdr =0.05) and GAF (d=-0.56; p fdr =0.04) with HD-tACS. HD-tDCS reduced SSVEP P1 (d=0.25; p fdr =0.005), which correlated with general psychopathology (ß=0.274, t=3.59, p=0.04). No significant differences in safety or tolerability measures were identified. Conclusions and Relevance: Lesion network guided HD-tES to the eVC is a safe, efficacious, and promising approach for reducing general psychopathology via changes in neuroplasticity. These results highlight the need for larger clinical trials implementing novel targeting methodologies for the treatments of psychosis. Trial Registration: ClinicalTrials.gov Identifier: NCT04870710. Key Points: Question: Is lesion network guided neurostimulation an efficacious, safe, and targeted approach for treating psychosis?Findings: In this single-center, nonrandomized, crossover, single-blind trial of 6 outpatients with psychosis, improvement in general psychopathology was seen in the short-term with HD-tDCS (high-definition transcranial direct current stimulation) and long-term with HD-tACS (alternating current) targeting the extrastriate visual cortex (eVC). HD-tDCS reduced early visual evoked responses which linked to general psychopathology improvements. Overall, both stimulations were well tolerated.Meaning: Study findings suggest that lesion network guided HD-tES to the eVC is a safe, efficacious, and promising approach for reducing general psychopathology via neuroplastic changes.

Tagging cortical networks in emotion: a topographical analysis.

Viewing emotional pictures is associated with heightened perception and attention, indexed by a relative increase in visual cortical activity. Visual cortical modulation by emotion is hypothesized to reflect re-entrant connectivity originating in higher-order cortical and/or limbic structures. The present study used dense-array electroencephalography and individual brain anatomy to investigate functional coupling between the visual cortex and other cortical areas during affective picture viewing. Participants viewed pleasant, neutral, and unpleasant pictures that flickered at a rate of 10 Hz to evoke steady-state visual evoked potentials (ssVEPs) in the EEG. The spectral power of ssVEPs was quantified using Fourier transform, and cortical sources were estimated using beamformer spatial filters based on individual structural magnetic resonance images. In addition to lower-tier visual cortex, a network of occipito-temporal and parietal (bilateral precuneus, inferior parietal lobules) structures showed enhanced ssVEP power when participants viewed emotional (either pleasant or unpleasant), compared to neutral pictures. Functional coupling during emotional processing was enhanced between the bilateral occipital poles and a network of temporal (left middle/inferior temporal gyrus), parietal (bilateral parietal lobules), and frontal (left middle/inferior frontal gyrus) structures. These results converge with findings from hemodynamic analyses of emotional picture viewing and suggest that viewing emotionally engaging stimuli is associated with the formation of functional links between visual cortex and the cortical regions underlying attention modulation and preparation for action.

Alpha oscillations and the control of voluntary saccadic behavior.

The purpose of this review is to explore the dynamic properties of alpha oscillations as biological covariates of intra- and inter-individual variance in saccadic behavior. A preponderance of research suggests that oscillatory dynamics in the alpha band co-vary with performance on a number of visuo-spatial cognitive tasks. Here we discuss a growing body of research relating these measures to saccadic behavior, focusing also on how task related and spontaneous measures of alpha oscillations may serve as potential biomarkers for ocular motor dysfunction in clinical populations.

Emotional perception: meta-analyses of face and natural scene processing.

Functional imaging studies of emotional processing typically contain neutral control conditions that serve to remove simple effects of visual perception, thus revealing the additional emotional process. Here we seek to identify similarities and differences across 100 studies of emotional face processing and 57 studies of emotional scene processing, using a coordinate-based meta-analysis technique. The overlay of significant meta-analyses resulted in extensive overlap in clusters, coupled with offset and unique clusters of reliable activity. The area of greatest overlap is the amygdala, followed by regions of medial prefrontal cortex, inferior frontal/orbitofrontal cortex, inferior temporal cortex, and extrastriate occipital cortex. Emotional face-specific clusters were identified in regions known to be involved in face processing, including anterior fusiform gyrus and middle temporal gyrus, and emotional scene studies were uniquely associated with lateral occipital cortex, as well as pulvinar and the medial dorsal nucleus of the thalamus. One global result of the meta-analysis reveals that a class of visual stimuli (faces vs. scenes) has a considerable impact on the resulting emotion effects, even after removing the basic visual perception effects through subtractive contrasts. Pure effects of emotion may thus be difficult to remove for the particular class of stimuli employed in an experimental paradigm. Whether a researcher chooses to tightly control the various elements of the emotional stimuli, as with posed face photographs, or allow variety and environmental realism into their evocative stimuli, as with natural scenes, will depend on the desired generalizability of their results.

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.

Neural Processing of Repeated Emotional Scenes in Schizophrenia, Schizoaffective Disorder, and Bipolar Disorder.

Impaired emotional processing and cognitive functioning are common in schizophrenia, schizoaffective disorder, and bipolar disorders, causing significant socioemotional disability. While a large body of research demonstrates abnormal cognition/emotion interactions in these disorders, previous studies investigating abnormalities in the emotional scene response using event-related potentials (ERPs) have yielded mixed findings, and few studies compare findings across psychiatric diagnoses. The current study investigates the effects of emotion and repetition on ERPs in a large, well-characterized sample of participants with schizophrenia-bipolar syndromes. Two ERP components that are modulated by emotional content and scene repetition, the early posterior negativity (EPN) and late positive potential (LPP), were recorded in healthy controls and participants with schizophrenia, schizoaffective disorder, bipolar disorder with psychosis, and bipolar disorder without psychosis. Effects of emotion and repetition were compared across groups. Results displayed significant but small effects in schizophrenia and schizoaffective disorder, with diminished EPN amplitudes to neutral and novel scenes, reduced LPP amplitudes to emotional scenes, and attenuated effects of scene repetition. Despite significant findings, small effect sizes indicate that emotional scene processing is predominantly intact in these disorders. Multivariate analyses indicate that these mild ERP abnormalities are related to cognition, psychosocial functioning, and psychosis severity. This relationship suggests that impaired cognition, rather than diagnosis or mood disturbance, may underlie disrupted neural scene processing in schizophrenia-bipolar syndromes.

The timing of emotional discrimination in human amygdala and ventral visual cortex.

Models of visual emotional perception suggest a reentrant organization of the ventral visual system with the amygdala. Using focused functional magnetic resonance imaging in humans with a sampling rate of 100 ms, here we determine the relative timing of emotional discrimination in amygdala and ventral visual cortical structures during emotional perception. Results show that amygdala and inferotemporal visual cortex differentiate emotional from nonemotional scenes approximately 1 s before extrastriate occipital cortex, whereas primary occipital cortex shows consistent activity across all scenes. This pattern of discrimination is consistent with a reentrant organization of emotional perception in visual processing, in which transaction between rostral ventral visual cortex and amygdala originates the identification of emotional relevance.

Emotional imagery: assessing pleasure and arousal in the brain's reward circuitry.

Research on emotional perception and learning indicates appetitive cues engage nucleus accumbens (NAc) and medial prefrontal cortex (mPFC), whereas amygdala activity is modulated by the emotional intensity of appetitive and aversive cues. This study sought to determine patterns of functional activation and connectivity among these regions during narrative emotional imagery. Using event-related fMRI, we investigate activation of these structures when participants vividly imagine pleasant, neutral, and unpleasant scenes. Results indicate that pleasant imagery selectively activates NAc and mPFC, whereas amygdala activation was enhanced during both pleasant and unpleasant imagery. NAc and mPFC activity were each correlated with the rated pleasure of the imagined scenes, while amygdala activity was correlated with rated emotional arousal. Functional connectivity of NAc and mPFC was evident throughout imagery, regardless of hedonic content, while correlated activation of the amygdala with NAc and mPFC was specific to imagining pleasant scenes. These findings provide strong evidence that pleasurable text-driven imagery engages a core appetitive circuit, including NAc, mPFC, and the amygdala.

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.