Mirtes G. Pereira

Load-dependent modulation of affective picture processing

Because of the biological significance of emotional stimuli, their processing is considered largely automatic. In the study reported herein, we tested the alternative hypothesis—namely, that the processing of emotional stimuli requires some level of attention. Our experiments utilized highly negative and arousing visual stimuli comprising mutilated bodies. All experiments employed a single task, which consisted of determining whether two peripheral bars were like oriented or not, thereby eliminating potential task-difference confounds that may have contaminated prior studies. Our results revealed that task-irrelevant unpleasant images slowed reaction time during the performance of the main task. Such interference was modulated by task difficulty as well as by alcohol consumption, showing that the processing of emotional visual stimuli is not immune to attentional manipulations. These results suggest that it is essential to utilize attentional manipulations that more fully consume attentional resources in order to demonstrate that the processing of emotional stimuli is resource limited.

Emotion affects action: Midcingulate cortex as a pivotal node of interaction between negative emotion and motor signals.

Affective pictures drive the activity of brain networks and impact behavior. We showed previously that viewing unpleasant pictures interfered in the performance of a basic nonemotional visual detection task. In the present study, we employed functional magnetic resonance imaging to test the hypothesis that behavioral interference may result from the interaction between negatively valenced and motor-related signals in the brain. As in our previous study (Pereira et al., 2006), participants performed a simple target detection task that followed the presentation of unpleasant or neutral pictures. Our results revealed that an unpleasant emotional context modulated evoked responses in several regions engaged by the simple target detection task. In particular, the midcingulate cortex was recruited when participants performed target detection trials during the unpleasant context, and signal responses in this region closely mirrored the pattern of behavioral interference (as revealed via reaction time). Our findings suggest that the midcingulate cortex may be an important site for the interaction between negatively valenced signals and motor signals in the brain and that it may be involved in the implementation of defensive responses, such as freezing.

Is tonic immobility the core sign among conventional peritraumatic signs and symptoms listed for PTSD

BACKGROUND Previous studies suggested the importance of peritraumatic reactions as predictors of PSTD symptoms severity. Despite mounting evidence that tonic immobility occurs under intense life threats its role as predictor of PTSD severity remains by and large understudied. The objective of this study was to investigate the role of peritraumatic reactions (tonic immobility, panic and dissociation) as predictors of PTSD symptoms severity. METHODS Participants were 32 victims of urban violence with PTSD diagnosed through the SCID-I. In order to evaluate PTSD symptoms at baseline, we used the Post-Traumatic Stress Disorder Checklist-Civilian Version. To assess peritraumatic reactions we employed the Physical Reactions Scale, the Peritraumatic Dissociative Experiences Questionnaire and Tonic Immobility questions. As confounding variables, we considered negative affect (measured by the Positive and Negative Affect Schedule-Trait Version), sex and time elapsed since trauma. RESULTS Tonic immobility was the only predictor of PTSD symptoms severity that kept the statistical significance after controlling for potential confounders. LIMITATIONS This study was based on a relatively small sample recruited in a tertiary clinic, a fact that may limit the generalizability of its findings. The retrospective design may have predisposed to recall bias. CONCLUSIONS Our study provides good reason to conduct more research on tonic immobility in PTSD with other samples and with different time frames in an attempt to replicate these stimulating results.

Avoidance of smoking: the impact of warning labels in Brazil

Background: Research on human emotion shows that pictures drive the activity of specialised brain networks affecting attitude and behaviour. Pictorial warnings on cigarette packages are considered one of the most effective ways to convey information on the health consequences of smoking. However, few studies have evaluated the effectiveness of warning labels to elicit avoidance of smoking. Objectives: To investigate the impact of pictorial health warnings conveyed by the Brazilian tobacco control programme through a well-established psychometric tool designed for studies on emotion and behaviour. Methods: Graphic Brazilian cigarette warnings labels were evaluated. They consisted of the two sets of warning pictures displayed in 2002–4 (n = 9) and 2004–8 (n = 10). Pleasant, unpleasant and neutral pictures selected from a standard catalogue were used as controls. Undergraduate students (n = 212, 18% smokers) evaluated the emotional content of each picture in two affective dimensions: hedonic valence and arousal. Participants were not provided with the sources of distinction between control and warning pictures. Results: The judgements of hedonic content of the warning pictures ranged from neutral to very unpleasant. None was classified as highly arousing. Smokers judged warning pictures representing people smoking significantly more pleasant than pictures without smoking scenes, and significantly more so than non-smokers. No significant differences between smokers and non-smokers were found for warning pictures without these smoking scenes. Conclusion: Previous studies have shown that the most threatening and arousing pictures prompt the greatest evidence of defensive activation. Emotional ratings of Brazilian warning pictures described them as unpleasant but moderately arousing. To intensify avoidance of the packages, future graphic warnings should therefore generate more arousal. The ratings for the Brazilian warning pictures indicated that, except for those depicting people smoking, judgements by smokers and non-smokers were similar, suggesting a potential applicability in both prevention and cessation. Smoking cues, however, should be avoided.

Decreased premotor cortex volume in victims of urban violence with posttraumatic stress disorder.

Background Studies addressing posttraumatic stress disorder (PTSD) have demonstrated that PTSD patients exhibit structural abnormalities in brain regions that relate to stress regulation and fear responses, such as the hippocampus, amygdala, anterior cingulate cortex, and ventromedial prefrontal cortex. Premotor cortical areas are involved in preparing to respond to a threatening situation and in representing the peripersonal space. Urban violence is an important and pervasive cause of human suffering, especially in large urban centers in the developing world. Violent events, such as armed robbery, are very frequent in certain cities, and these episodes increase the risk of PTSD. Assaultive trauma is characterized by forceful invasion of the peripersonal space; therefore, could this traumatic event be associated with structural alteration of premotor areas in PTSD? Methodology/Principal Findings Structural magnetic resonance imaging scans were acquired from a sample of individuals that had been exposed to urban violence. This sample consisted of 16 PTSD patients and 16 age- and gender-matched controls. Psychometric questionnaires differentiated PTSD patients from trauma-exposed controls with regard to PTSD symptoms, affective, and resilience predispositions. Voxel-based morphometric analysis revealed that, compared with controls, the PTSD patients presented significant reductions in gray matter volume in the ventral premotor cortex and in the pregenual anterior cingulate cortex. Conclusions Volume reduction in the premotor cortex that is observed in victims of urban violence with PTSD may be associated with a disruption in the dynamical modulation of the safe space around the body. The finding that PTSD patients presented a smaller volume of pregenual anterior cingulate cortex is consistent with the results of other PTSD neuroimaging studies that investigated different types of traumatic events.

EEG correlates of the severity of posttraumatic stress symptoms: A systematic review of the dimensional PTSD literature

BACKGROUND Considering the Research Domain Criteria (RDoC) framework, it is crucial to investigate posttraumatic stress disorder (PTSD) as a spectrum that ranges from normal to pathological. This dimensional approach is especially important to aid early PTSD detection and to guide better treatment options. In recent years, electroencephalography (EEG) has been used to investigate PTSD; however, reviews regarding EEG data related to PTSD are lacking, especially considering the dimensional approach. This systematic review examined the literature regarding EEG alterations in trauma-exposed people with posttraumatic stress symptoms (PTSS) to identify putative EEG biomarkers of PTSS severity. METHOD A systematic review of EEG studies of trauma-exposed participants with PTSS that reported dimensional analyses (e.g., correlations or regressions) between PTSS and EEG measures was performed. RESULTS The literature search yielded 1178 references, of which 34 studies were eligible for inclusion. Despite variability among the reviewed studies, the PTSS severity was often associated with P2, P3-family event-related potentials (ERPs) and alpha rhythms. LIMITATIONS The search was limited to articles published in English; no information about non-published studies or studies reported in other languages was obtained. Another limitation was the heterogeneity of studies, which made meta-analysis challenging. CONCLUSIONS EEG provides promising candidates to act as biomarkers, although further studies are required to confirm the findings. Thus, EEG, in addition to being cheaper and easier to implement than other central techniques, has the potential to reveal biomarkers of PTSS severity.

Implicit motivational impact of pictorial health warning on cigarette packs.

Objective The use of pictorial warning labels on cigarette packages is one of the provisions included in the first ever global health treaty by the World Health Organization against the tobacco epidemic. There is substantial evidence demonstrating the effectiveness of graphic health warning labels on intention to quit, thoughts about health risks and engaging in cessation behaviors. However, studies that address the implicit emotional drives evoked by such warnings are still underexplored. Here, we provide experimental data for the use of pictorial health warnings as a reliable strategy for tobacco control. Methods Experiment 1 pre-tested nineteen prototypes of pictorial warnings to screen for their emotional impact. Participants (n = 338) were young adults balanced in gender, smoking status and education. Experiment 2 (n = 63) tested pictorial warnings (ten) that were stamped on packs. We employed an innovative set-up to investigate the impact of the warnings on the ordinary attitude of packs’ manipulation, and quantified judgments of warnings’ emotional strength and efficacy against smoking. Findings Experiment 1 revealed that women judged the warning prototypes as more aversive than men, and smokers judged them more aversive than non-smokers. Participants with lower education judged the prototypes more aversive than participants with higher education. Experiment 2 showed that stamped warnings antagonized the appeal of the brands by imposing a cost to manipulate the cigarette packs, especially for smokers. Additionally, participants’ judgments revealed that the more aversive a warning, the more it is perceived as effective against smoking. Conclusions Health warning labels are one of the key components of the integrated approach to control the global tobacco epidemic. The evidence presented in this study adds to the understanding of how implicit responses to pictorial warnings may contribute to behavioral change.

Autonomic reactions to mutilation pictures: Positive affect facilitates safety signal processing

For survival, humans are continuously vigilant for signs of danger. Equally important, but less studied, is our ability to detect and respond to safety cues. The trait of positive affect may be a key component determining human variability in safety detection. Here we investigate autonomic and self-report reactivity to pictures of mutilated bodies, after reading a text about the art of mimicking injuries in the movies. Participants that scored high in positive affect trait showed attenuated autonomic reactions to the mutilation pictures. Thus, high positive affect facilitated engagement in safety cues and modulated reflexive reactions of the brains defense system.

Antecedent descriptions change brain reactivity to emotional stimuli: a functional magnetic resonance imaging study of an extrinsic and incidental reappraisal strategy.

In the present study we investigated whether individuals would take advantage of an extrinsic and incidental reappraisal strategy by giving them precedent descriptions to attenuate the emotional impact of unpleasant pictures. In fact, precedent descriptions have successfully promoted down-regulation of electrocortical activity and physiological responses to unpleasant pictures. However, the neuronal substrate underlying this effect remains unclear. Particularly, we investigated whether amygdala and insula responses, brain regions consistently implicated in emotional processing, would be modulated by this strategy. To achieve this, highly unpleasant pictures were shown in two contexts in which a prior description presented them as taken from movie scenes (fictitious) or real scenes. Results showed that the fictitious condition was characterized by down-regulation of amygdala and insula responses. Thus, the present study provides new evidence on reappraisal strategies to down-regulate emotional reactions and suggest that amygdala and insula responses to emotional stimuli are adaptive and highly flexible.

How you perceive threat determines your behavior

The prioritization of processing emotional stimuli usually produces deleterious effects on task performance when it distracts from a task. One common explanation is that brain resources are consumed by emotional stimuli, diverting resources away from executing the task. Viewing unpleasant stimuli also generates defensive reactions, and these responses may be at least partially responsible for the effect of the emotional modulation observed in various reaction time (RT) paradigms. We investigated whether modulatory effects on RT vary if we presented threat stimuli to prompt different defensive responses. To trigger different responses, we manipulated threat perception by moving the direction of threatening stimuli. Threatening or neutral stimuli were presented as distractors during a bar orientation discrimination task. The results demonstrated that threat stimuli directed toward the observer produced a decrease in RT; in contrast, threat stimuli directed away from the observer produced an increase in RT, when compared to neutral stimuli. Accelerated RT during directed toward threat stimuli was attributed to increased motor preparation resulting from strong activation of the defense response cascade. In contrast, directed away threat stimuli likely activated the defense cascade, but less intensively, prompting immobility. Different threat stimuli produced varying effects, which was interpreted as evidence that the modulation of RT by emotional stimuli represents the summation of attentional and motivational effects. Additionally, participants who had been previously exposed to diverse types of violent crime were more strongly influenced by threat stimuli directed toward the observer. In sum, our data support the concept that emotions are indeed action tendencies.