Hit or Run: Exploring Aggressive and Avoidant Reactions to Interpersonal Provocation Using a Novel Fight-or-Escape Paradigm (FOE)

Interpersonal provocation presents an approach-avoidance conflict to the provoked person: responding aggressively might yield the joy of retribution, whereas withdrawal can provide safety. Experimental aggression studies typically measure only retaliation intensity, neglecting whether individuals want to confront the provocateur at all. To overcome this shortcoming of previous measures, we developed and validated the Fight-or-Escape paradigm (FOE). The FOE is a competitive reaction time task in which the winner can choose the volume of a sound blast to be directed at his/her opponent. Participants face two ostensible opponents who consistently select either high or low punishments. At the beginning of each trial, subjects are given the chance to avoid the encounter for a limited number of times. In a first experiment (n=27, all women), we found that fear potentiation of the startle response was related to lower scores in a composite measure of aggression and avoidance against the provoking opponent. In a second experiment (n=34, 13 men), we altered the paradigm such that participants faced the opponents in alternating rather than in random order. Participants completed the FOE as well as the Dot-Probe Task (DPT) and the Approach-Avoidance Task (AAT). Subjects with higher approach bias scores in the AAT avoided the provoking opponent less frequently. Hence, individuals with high threat reactivity and low approach motivation displayed more avoidant responses to provocation, whereas participants high in approach motivation were more likely to engage in aggressive interactions when provoked. The FOE is thus a promising laboratory measure of avoidance and aggression

Endogenous testosterone is associated with lower amygdala reactivity to angry faces and reduced aggressive behavior in healthy young women

Testosterone and cortisol have been proposed to influence aggressive behavior by altering the neural processing of facial threat signals. However, this has not been investigated in direct social interactions. Here, we explored the joint impact of testosterone, cortisol, and brain reactivity to anger expressions on women's reactive aggression in the Social Threat Aggression Paradigm (STAP). The STAP is a competitive reaction time task in which the purported opponent displays either an angry or a neutral facial expression at the beginning of each trial and delivers increasingly loud sound blasts to the participants, successfully provoking them. Strikingly, salivary testosterone at scan-time was negatively related to both aggression and basolateral amygdala (BLA) reactivity to angry faces, whereas cortisol had no effect. When the opponent looked angry, BLA-orbitofrontal coupling was reduced, and BLA reactivity was positively related to aggression. The latter relationship was fully mediated by bilateral superior temporal gyrus (STG) activation. Our results thus support previous neurobiological models of aggression, and extend them by demonstrating that fast amygdala responses to threat modulate STG activity in order to favor aggressive retaliation. Furthermore, our study agrees with recent evidence underscoring a fear-reducing and strategically prosocial effect of testosterone on human social behavior

Neural basis of shame and guilt experience in women with borderline personality disorder

Borderline personality disorder (BPD) is characterized by instability of affect, emotion dysregulation, and interpersonal dysfunction. Especially shame and guilt, so-called self-conscious emotions, are of central clinical relevance to BPD. However, only few experimental studies have focused on shame or guilt in BPD and none investigated their neurobiological underpinnings. In the present functional magnetic resonance imaging study, we took a scenario-based approach to experimentally induce feelings of shame, guilt, and disgust with neutral scenarios as control condition. We included 19 women with BPD (age 26.4 ± 5.8 years; DSM-IV diagnosed; medicated) and 22 healthy female control subjects (age 26.4 ± 4.6 years; matched for age and verbal IQ). Compared to controls, women with BPD reported more intense feelings when being confronted with affective scenarios, especially higher levels of shame, guilt, and fear. We found increased amygdala reactivity in BPD compared to controls for shame and guilt, but not for disgust scenarios (p = 0.05 FWE corrected at the cluster level; p < 0.0001 cluster defining threshold). Exploratory analyses showed that this was caused by a diminished habituation in women with BPD relative to control participants. This effect was specific to guilt and shame scenarios as both groups showed amygdala habituation to disgust scenarios. Our work suggests that heightened shame and guilt experience in BPD is not related to increased amygdala activity per se, but rather to decreased habituation to self-conscious emotions. This provides an explanation for the inconsistencies in previous imaging work on amygdala involvement in BPD as well as the typically slow progress in the psychotherapy of dysfunctional self-conscious emotions in this patient group

Trait aggressiveness is not related to structural connectivity between orbitofrontal cortex and amygdala.

Studies in both pathological and healthy samples have suggested altered functional connectivity between orbitofrontal cortex (OFC) and amygdala as a possible cause of anger and aggression. In patient populations presenting with pathological aggression, there is also evidence for changes in structural connectivity between OFC and amygdala. In healthy samples, however, the relationship between white matter integrity and aggression has not been studied to date. Here, we investigated the relationship between trait aggressiveness and structural OFC-amygdala connectivity in a large sample (n = 93) of healthy young men. Using diffusion tensor imaging, we measured the distribution of fractional anisotropy and mean diffusivity along the uncinate fascicle bilaterally. We found no differences in either measure between participants high and low in physical aggressiveness, or between those high and low in trait anger. Our results therefore argue against a direct relationship between structural OFC-amygdala connectivity and normal-range trait aggressiveness

Hit or Run: Exploring Aggressive and Avoidant Reactions to Interpersonal Provocation Using a Novel Fight-or-Escape Paradigm (FOE)

Interpersonal provocation presents an approach-avoidance conflict to the provoked person: responding aggressively might yield the joy of retribution, whereas withdrawal can provide safety. Experimental aggression studies typically measure only retaliation intensity, neglecting whether individuals want to confront the provocateur at all. To overcome this shortcoming of previous measures, we developed and validated the Fight-or-Escape paradigm (FOE). The FOE is a competitive reaction time (RT) task in which the winner can choose the volume of a sound blast to be directed at his/her opponent. Participants face two ostensible opponents who consistently select either high or low punishments. At the beginning of each trial, subjects are given the chance to avoid the encounter for a limited number of times. In a first experiment (n = 27, all women), we found that fear potentiation (FP) of the startle response was related to lower scores in a composite measure of aggression and avoidance against the provoking opponent. In a second experiment (n = 34, 13 men), we altered the paradigm such that participants faced the opponents in alternating rather than in random order. Participants completed the FOE as well as the Dot-Probe Task (DPT) and the Approach-Avoidance Task (AAT). Subjects with higher approach bias scores in the AAT avoided the provoking opponent less frequently. Hence, individuals with high threat reactivity and low approach motivation displayed more avoidant responses to provocation, whereas participants high in approach motivation were more likely to engage in aggressive interactions when provoked. The FOE is thus a promising laboratory measure of avoidance and aggression

Descriptive results.

<p>The distribution of mean FA-values along the left uncinate fascicle (UF) between the tract defining regions of interest (ROIs) is shown (<b>A</b>). Standard deviations for each of the 100 nodes are shown in blue. <b>B</b> shows the distribution of FA-values along the left UF for a representative subject. Tract-defining ROIs are depicted in red. <b>C</b> shows mean FA-values for the low and high aggressive groups as defined by the median split based on physical aggression scores for node 83 of the left uncinate fascicle. Single subject FA-values are depicted for the nine participants with the lowest and highest aggression scores. Data points encircled in black represent two cases.</p

Heavy-atom tunneling in semibullvalenes

The Cope rearrangement of selectively deuterated isotopomers of 1,5-dimethylsemibullvalene $\bf {2 a}$ and 3,7-dicyano-1,5-dimethylsemibullvalene $\bf {2 b}$ were studied in cryogenic matrices. In both semibullvalenes the Cope rearrangement is governed by heavy-atom tunneling. The driving force for the rearrangements is the small difference in the zero-point vibrational energies of the isotopomers. To evaluate the effect of the driving force on the tunneling probability in $\bf {2 a}$ and $\bf {2 b}$, two different pairs of isotopomers were studied for each of the semibullvalenes. The reaction rates for the rearrangement of $\bf {2 b}$ in cryogenic matrices were found to be smaller than the ones of $\bf {2 a}$ under similar conditions, whereas differences in the driving force do not influence the rates. Small curvature tunneling (SCT) calculations suggest that the reduced tunneling rate of $\bf {2 b}$ compared to that of $\bf {2 a}$ results from a change in the shape of the potential energy barrier. The tunneling probability of the semibullvalenes strongly depends on the matrix environment; however, for $\bf {2 a}$ in a qualitatively different way than for $\bf {2 b}$