Effects of emotional valence and three-dimensionality of visual stimuli on brain activation: an fMRI study

The impact of emotional valence and stimulus habituation on fMRI signal reliability during emotion generation

BACKGROUND

The emotional domain is often impaired across many neurological diseases, for this reason it represents a relevant target of rehabilitation interventions. Functional changes in neural activity related to treatment can be assessed with functional MRI (fMRI) using emotion-generation tasks in longitudinal settings. Previous studies demonstrated that within-subject fMRI signal reliability can be affected by several factors such as repetition suppression, type of task and brain anatomy. However, the differential role of repetition suppression and emotional valence of the stimuli on the fMRI signal reliability and reproducibility during an emotion-generation task involving the vision of emotional pictures is yet to be determined.

METHODS

Sixty-two healthy subjects were enrolled and split into two groups: group A (21 subjects, test-retest reliability on same-day and with same-task-form), group B (30 subjects, test-retest reproducibility with 4-month-interval using two equivalent-parallel forms of the task). Test-retest reliability and reproducibility of fMRI responses and patterns were evaluated separately for positive and negative emotional valence conditions in both groups. The analyses were performed voxel-wise, using the general linear model (GLM), and via a region-of-interest (ROI)-based approach, by computing the intra-class correlation coefficient (ICC) on the obtained contrasts.

RESULTS

The voxel-wise GLM test yielded no significant differences for both conditions in reliability and reproducibility analyses. As to the ROI-based approach, across all areas with significant main effects of the stimuli, the reliability, as measured with ICC, was poor (<0.4) for the positive condition and ranged from poor to excellent (0.4-0.75) for the negative condition. The ICC-based reproducibility analysis, related to the comparison of two different parallel forms, yielded similar results.

DISCUSSION

The voxel-wise GLM analysis failed to capture the poor reliability of fMRI signal which was instead highlighted using the ROI-based ICC analysis. The latter showed higher signal reliability for negative valence stimuli with respect to positive ones. The implementation of two parallel forms allowed to exclude neural suppression as the predominant effect causing low signal reliability, which could be instead ascribed to the employment of different neural strategies to cope with emotional stimuli over time. This is an invaluable information for a better assessment of treatment and rehabilitation effects in longitudinal studies of emotional neural processing.

Virtual Reality Erotica: Exploring General Presence, Sexual Presence, Sexual Arousal, and Sexual Desire in Women

Virtual reality (VR) media using a three-dimensional (3D) camera facilitates an immersive experience compared to traditional two-dimensional (2D) formats. In this novel study, we used high quality, women-centered erotica and examined whether stimulus modality (VR vs. 2D) and point of view (POV: first-person vs. third-person) impacted women's feelings of sexual presence (activation of sexual response induced by the perception of being present), sexual arousal, and sexual desire (dyadic and solitary). We also investigated the effects of stimulus modality on feelings of general presence (a sense of "being there"). Results from 38 women indicated that with medium to large effects, general presence, sexual presence, and sexual arousal were significantly higher for VR videos relative to 2D videos. Sexual presence was higher for first-person POV depending on the order of film exposure. A general trend toward increasing dyadic sexual desire over the course of the study was observed. No significant differences were observed for solitary sexual desire. These findings support the adaptability of VR media to sex research and show that it can induce feelings of sexual presence and presence more generally. That sexual arousal was positively impacted by VR erotica may have implications for addressing the limitations that accompany other stimulus modalities used to elicit sexual responses in women.

Contextual factors modulate risk preferences in adult humans

Humans have generally been considered risk averse for gains. Yet, growing evidence shows that risk preferences may change across reward currencies and depend on the type of tasks used to measure them. Here, we examined how context affects human risk preferences to shed light on the psychological mechanisms underlying human decision-making under risk. Participants were presented with a descriptive risky choice task involving repeated choices between real options and they were provided with trial-by-trial feedback. We manipulated the type of reward and, for the first time, the format of the choice stimuli. Options were either 2D computer-based images or concrete 3D objects, and participants received food or money as reward. First, we found that participants were more risk-seeking for food compared to money, suggesting that people treat money differently from consumable rewards. Second, we found that people were more risk-seeking when they made choices between concrete 3D objects than between 2D computer-based images. Our results strengthened the evidence that human choice patterns may change depending on the context and, for the first time, showed that the format of the choice stimuli does affect risk preferences, an important consideration for future research.

Stereoscopic Rendering via Goggles Elicits Higher Functional Connectivity During Virtual Reality Gaming

Virtual reality (VR) simulates real-world scenarios by creating a sense of presence in its users. Such immersive scenarios lead to behavior that is more similar to that displayed in real world settings, which may facilitate the transfer of knowledge and skills acquired in VR to similar real world situations. VR has already been used in education, psychotherapy, rehabilitation and it comes as an appealing choice for training intervention purposes. The aim of the present study was to investigate to what extent VR technology for games presented via goggles can be used in a magnetic resonance imaging scanner (MRI), addressing the question of whether brain connectivity differs between VR stimulation via goggles and a presentation from a screen via mirror projection. Moreover, we wanted to investigate whether stereoscopic goggle stimulation, where both eyes receive different visual input, would elicit stronger brain connectivity than a stimulation in which both eyes receive the same visual input (monoscopic). To our knowledge, there is no previous research using games and functional connectivity (FC) in MRI to address this question. Multiple analyses approaches were taken so that different aspects of brain connectivity could be covered: fractional low-frequency fluctuation, independent component analysis (ICA), seed-based FC (SeedFC) and graph analysis. In goggle presentation (mono and stereoscopic) as contrasted to screen, we found differences in brain activation in left cerebellum and postcentral gyrus as well as differences in connectivity in the visual cortex and frontal inferior cortex [when focusing on the visual and default mode network (DMN)]. When considering connectivity in specific areas of interest, we found higher connectivity between bilateral superior frontal cortex and the temporal lobe, as well as bilateral inferior parietal cortex with right calcarine and right lingual cortex. Furthermore, we found superior frontal cortex and insula/putamen to be more strongly connected in goggle stereoscopic vs. goggle monoscopic, in line with our hypothesis. We assume that the condition that elicits higher brain connectivity values should be most suited for long-term brain training interventions given that, extended training under these conditions could permanently improve brain connectivity on a functional as well as on a structural level.

Psychophysiological reactivity, coping behaviour and intrusive memories upon multisensory Virtual Reality and Script-Driven Imagery analogue trauma: A randomised controlled crossover study

BACKGROUND

Peri- and post-traumatic factors predict the differential development of stress-associated mental disorders. Prospective designs assessing these risk factors in real-time under controlled experimental conditions can overcome limitations of retrospective designs. Therefore, we aimed to investigate multi-sensory, experimental analogues of a traumatic experience delivered in Virtual Reality (VR) or Script-Driven Imagery (SDI).

METHODS

In a randomised controlled crossover design, differences in the induced analogue trauma symptoms between multi-sensory analogue trauma by either VR or SDI versus a neutral condition were assessed in 127 non-clinical participants.

RESULTS

Analogue symptoms (psychophysiological responses, coping behaviour and intrusive memories of the experimental trauma) increased following analogue trauma in both VR and SDI, with more analogue symptoms for VR. Psychophysiological arousal was in general higher in VR.

LIMITATIONS

The analogue trauma situation of a car park fire that was used may be infrequent in real life.

CONCLUSIONS

Multisensory (vision, olfaction, hearing) analogue trauma in VR and SDI offers a useful tool for the induction and real-time assessment of peri- and post-traumatic risk factors for analogue stress-associated psychopathology. VR was more effective in inducing analogue symptoms than SDI, even though the latter might be more personalised. New experimental models for studying trauma exposure and responses may contribute to a better understanding of risk factors and help to identify and protect individuals at risk.

Virtual Viewing Time: The Relationship between Presence and Sexual Interest in Androphilic and Gynephilic Men

Virtual Reality (VR) has successfully been used in the research of human behavior for more than twenty years. The main advantage of VR is its capability to induce a high sense of presence. This results in emotions and behavior which are very close to those shown in real situations. In the context of sex research, only a few studies have used high-immersive VR so far. The ones that did can be found mostly in the field of forensic psychology. Nevertheless, the relationship between presence and sexual interest still remains unclear. The present study is the first to examine the advantages of high-immersive VR in comparison to a conventional standard desktop system regarding their capability to measure sexual interest. 25 gynephilic and 20 androphilic healthy men underwent three experimental conditions, which differed in their ability to induce a sense of presence. In each condition, participants were asked to rate ten male and ten female virtual human characters regarding their sexual attractiveness. Without their knowledge, the subjects' viewing time was assessed throughout the rating. Subjects were then asked to rate the sense of presence they had experienced as well as their perceived realism of the characters. Results suggested that stereoscopic viewing can significantly enhance the subjective sexual attractiveness of sexually relevant characters. Furthermore, in all three conditions participants looked significantly longer at sexually relevant virtual characters than at sexually non-relevant ones. The high immersion condition provided the best discriminant validity. From a statistical point of view, however, the sense of presence had no significant influence on the discriminant validity of the viewing time task. The study showed that high-immersive virtual environments enhance realism ratings as well as ratings of sexual attractiveness of three-dimensional human stimuli in comparison to standard desktop systems. Results also show that viewing time seems to be influenced neither by sexual attractiveness nor by realism of stimuli. This indicates how important task specific mechanisms of the viewing time effect are.

Effects of emotion regulation difficulties on the tonic and phasic cardiac autonomic response

Background

Emotion regulation theory aims to explain the interactions between individuals and the environment. In this context, Emotion Regulation Difficulties (ERD) disrupt the physiological component of emotions through the autonomic nervous system and are involved in several psychopathological states.

Objective

We were interested in comparing the influence of a film-elicited emotion procedure on the autonomic nervous system activity of two groups with different levels of emotion regulation difficulties.

Methods

A total of 63 women (undergraduate students) ranging from 18 to 27 (20.7±1.99) years old were included. Using the upper and lower quartile of a questionnaire assessing the daily difficulties in regulating emotions, two groups, one with low (LERD) and one with high (HERD) levels of emotion regulation difficulties, were constituted and studied during a film-elicited emotion procedure. Cardiac vagal activity (HF-HRV) was analyzed during three periods: baseline, film-elicited emotion, and recovery.

Results

The cardiovascular results showed a decrease in HF-HRV from baseline to elicitation for both groups. Then, from elicitation to recovery, HF-HRV increased for the LERD group, whereas a low HF-HRV level persisted for the HERD group.

Conclusions

The HERD group exhibited inappropriate cardiac vagal recovery after a negative emotion elicitation had ended. Cardiac vagal tone took longer to return to its initial state in the HERD group than in the LERD group. Prolonged cardiac vagal suppression might constitute an early marker of emotion regulation difficulties leading to lower cardiac vagal tone.