A quasi-experimental study in sibling dyads: differential provocation-aggression patterns in the interactive taylor aggression paradigm.

Introduction: The Taylor Aggression Paradigm (TAP) is a well-established tool for assessing provocation-induced reactive aggression. We introduce an interactive version, the iTAP, with real-time opponents across 60 trials, including five simulated provocation trials in the middle. In this quasi-experimental study, we evaluate the effectiveness of the paradigm to investigate reactive aggression in interacting participants. The design allows us to employ the TAP in settings of high familiarity dyads, addressing an existing gap. Method: Twenty-eight healthy same-sex adult sibling pairs (N = 56) competed against each other in the iTAP, exemplifying high familiarity through their social and emotional co-development, and mutual knowledge. Additionally, we explore naturally arising aggression types in terms of sibling pairs' reciprocal aggression trajectories across trials. Lastly, we investigate situational and personal variables influencing reactive aggression on the iTAP within high familiarity dyads. Results: In line with non-interactive TAP versions, siblings employed a global "tit-for-tat" strategy in response to heightened provocation: Aggression increased during manipulated trials of increasing provocation, persisted during real interaction and declined in the final block, suggesting sibling co-regulation which was underscored by the convergence in within-pair aggression level. We found no gender differences in these dynamics but a trend for higher initial aggression levels within brother pairs and higher responsiveness to increased provocation in sister pairs. Overall aggression levels were related to situational variables including trial outcome (lost, won, and tie), Further, siblings' state anger correlated positively with aggression scores on the iTAP. Aggression was not reliably related to personal variables predicting aggression. We identified subgroups of sibling pairs with distinct provocation-aggression patterns related to differences in reported behavioral motivations and emotional states. The results highlight situational over personal variables in determining aggressive behavior on the task in this sample of healthy adults. While no direct link between sibling relationship quality and aggression was found, the overall behavior was likely influenced by the familiarity between siblings and the specific context of their relationship. Conclusion: The iTAP demonstrates promise as a tool for studying reciprocal aggressive behavior. The emergence of different interaction patterns underscores the ecological validity introduced by the interactive context, which complements the standard versions of the TAP.

Elevated Insulin Levels Engage the Salience Network during Multisensory Perception.

INTRODUCTION: Brain insulin reactivity has been reported in connection with systematic energy metabolism, enhancement in cognition, olfactory sensitivity, and neuroendocrine circuits. High receptor densities exist in regions important for sensory processing. The main aim of the study was to examine whether intranasal insulin would modulate the activity of areas in charge of olfactory-visual integration. METHODS: As approach, a placebo-controlled double-blind within crossover design was chosen. The experiments were conducted in a research unit of a university hospital. On separate mornings, twenty-six healthy normal-weight males aged between 19 and 31 years received either 40 IU intranasal insulin or placebo vehicle. Subsequently, they underwent 65 min of functional magnetic resonance imaging whilst performing an odor identification task. Functional brain activations of olfactory, visual, and multisensory integration as well as insulin versus placebo were assessed. Regarding the odor identification task, reaction time, accuracy, pleasantness, and intensity measurements were taken to examine the role of integration and treatment. Blood samples were drawn to control for peripheral hormone concentrations. RESULTS: Intranasal insulin administration during olfactory-visual stimulation revealed strong bilateral engagement of frontoinsular cortices, anterior cingulate, prefrontal cortex, mediodorsal thalamus, striatal, and hippocampal regions (p ≤ 0.001 familywise error [FWE] corrected). In addition, the integration contrast showed increased activity in left intraparietal sulcus, left inferior frontal gyrus, left superior frontal gyrus, and left middle frontal gyrus (p ≤ 0.013 FWE corrected). CONCLUSIONS: Intranasal insulin application in lean men led to enhanced activation in multisensory olfactory-visual integration sites and salience hubs which indicates stimuli valuation modulation. This effect can serve as a basis for understanding the connection of intracerebral insulin and olfactory-visual processing.

The role of dominance in sibling relationships: differences in interactive cooperative and competitive behavior.

Siblings strongly influence each other in their social development and are a major source of support and conflict. Yet, studies are mostly observational, and little is known about how adult sibling relationships influence social behavior. Previous tasks exploring dynamically adjusting social interactions have limitations in the level of interactivity and naturalism of the interaction. To address these limitations, we created a cooperative tetris puzzle-solving task and an interactive version of the chicken game task. We validated these two tasks to study cooperative and competitive behavior in real-time interactions (N = 56). Based on a dominance questionnaire (DoPL), sibling pairs were clustered into pairs that were both low in dominance (n = 7), both high in dominance (n = 8), or one low and one high in dominance (n = 13). Consistent with our hypothesis, there were significantly more mutual defections, less use of turn-taking strategies, and a non-significant trend for reduced success in solving tetris puzzles together among high dominance pairs compared to both other pair types. High dominant pairs also had higher Machiavellian and hypercompetitiveness traits and more apathetic sibling relationships. Both tasks constitute powerful and reliable tools to study personality and relationship influences on real and natural social interactions by demonstrating the different cooperative and competitive dynamics between siblings.

Gender-Dependent Crossmodal Interactions Between Olfactory and Tactile Stimulation Revealed Using the Unimodal Tactile Stimulation Device (UniTaSD).

Due to the complex stimulation methods required, olfaction and touch are 2 relatively understudied senses in the field of perceptual (neuro-)science. In order to establish a consistent presentation method for the bimodal stimulation of these senses, we combined an olfactometer with the newly developed Unimodal Tactile Stimulation Device. This setup allowed us to study the influence of olfaction on tactile perception and opened up an unexplored field of research by examining the crossmodal influence of tactile stimuli on olfaction. Using a pseudorandomized design, we analyzed how positive or negative tactile and olfactory stimuli influenced the opposing modality's perceived intensity and pleasantness. By asking participants to rate tactile stimuli, we were able to reproduce previously reported differences indicating that bimodal presentation with an olfactory stimulus increases or reduces perceived tactile pleasantness in an odor-dependent manner while highlighting that this effect appears unique to women. Furthermore, we found the first evidence for the influence of tactile stimuli on perceived odor pleasantness, an effect that is also driven primarily by women in our study. Based on these findings we believe that future neurophysiological studies, using controlled stimulus presentation can help unravel how and why olfactory and tactile perception interact in the human brain.

Virtual grocery shopping and cookie consumption following intranasal insulin or placebo application.

Insulin receptors are present in brain areas that are involved in the control of hunger and satiety, and intranasal insulin is assumed to have an anorexigenic effect. This known influence of insulin on satiety encouraged us to investigate the effect of intranasal insulin on feeding-related behaviors. The aim of the current study was to explore the influence of 40 IU of intranasal insulin on the grocery shopping behavior and cookie consumption in a group of 30 healthy young men, using a crossover randomized double-blind design. Using a virtual mock supermarket, we tested whether the intranasal administration of insulin influences purchase behavior in comparison to a placebo or control condition. The participants also provided hedonic ratings of food pictures, as well as their subjective feeling of hunger. We calculated an objective measure of hunger from the amount of cookies eaten. In contradiction to our hypotheses, no significant differences regarding ratings, calorie content of purchased food products, and cookie consumption were found between the treatment conditions. Our conclusion is that 40 IU intranasal insulin had no influence on the evaluation of pictured foods in healthy young men in our task. Acknowledging that previous studies have found effects for intranasal insulin and food cue processing, we suggest that future research should focus on chemosensory stimulation or cognitive tasks in behavioral experiments and carefully consider the doses of intranasal insulin. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

A Masked Aversive Odor Cannot Be Discriminated From the Masking Odor but Can Be Identified Through Odor Quality Ratings and Neural Activation Patterns.

Odor masking is a very prominent problem in our daily routines, mainly concerning unpleasant sweat or toilet odors. In the current study we explored the effectiveness of odor masking both on a behavioral and neuronal level. By definition, participants cannot differentiate a fully masked unpleasant odor from the pleasant pure odor used as a masking agent on a behavioral level. We hypothesized, however, that one can still discriminate between a fully masked odor mixture and the pure masking odor on a neuronal level and that, using a reinforcing feedback paradigm, participants could be trained to perceive this difference. A pleasant, lemon-like odor (citral) and a mixture of citral and minor amounts of an unpleasant, goat-like odor (caproic acid) were presented to participants repeatedly using a computer-controlled olfactometer and participants had to decide whether two presented stimuli were the same or different. Accuracy of this task was incentivized with a possible monetary reward. Functional imaging was used throughout the task to investigate central processing of the two stimuli. The participants rated both stimuli as isopleasant and isointense, indicating that the unpleasant odor was fully masked by the pleasant odor. The isolated caproic acid component of the mixture was rated less pleasant than the pleasant odor in a prior experimental session. Although the masked and pure stimuli were not discriminated in the forced-choice task, quality ratings on a dimensional scale differed. Further, we observed an increased activation of the insula and ventral striatum/putamen for the pure in contrast to the fully masked odor, hence revealing a difference in neuronal processing. Our hypothesis that perceptual discrimination and neuronal processing can be enhanced using a reinforcing feedback paradigm is not supported by our data.

Eucalyptol Masks the Olfactory But Not the Trigeminal Sensation of Ammonia.

Eucalyptol is a substance with rather pleasant olfactory and trigeminal characteristics and is thus suggested as an efficient tool for malodor coverage. In this study ammonia would be the malodor substance such as is found in cat litter or hair coloration. We investigated the potential of eucalyptol to inhibit both the olfactory as well as the trigeminal sensation of ammonia. For this purpose, we mixed eucalyptol and ammonia and compared odor component intensities. After being presented with either the pure odors or a binary mixture thereof, 21 young and healthy participants had to lateralize the odors and rate component (eucalyptol and ammonia) and total intensity. Analysis of intensity ratings revealed hypoadditivity (total mixture intensity was less than the sum of the total intensity of the single components). Significant interaction effects verified that mixing eucalyptol and ammonia only affected the perceived intensity of ammonia. Comparing the odor components within the pure and mixed stimuli, the ammonia component was rated as significantly less intense in the mixture compared to pure ammonia whereas the eucalyptol component was rated equal in the pure and mixed condition. On the basis of lateralization scores, we observed trigeminal mixture enhancement. We conclude that eucalyptol is a suitable masking agent to cover the unpleasant smell of ammonia; however, it fails to serve as an ammonia counterirritant because it lacks the ability to mask the trigeminal sensation of ammonia.

Semantic Congruence Alters Functional Connectivity during Olfactory-Visual Perception.

Previous research has shown that humans struggle to interpret multiple perceptual signals when the information provided by these signals is incongruent. In the context of olfactory-visual integration, behavioral and neuronal differences in response to congruent and incongruent stimulus pairs have been established. Here, we explored functional connectivity of the human brain with regard to the perception of congruent and incongruent food stimuli. Participants were simultaneously presented olfactory and visual stimuli of 4 different food objects, 2 healthy and 2 unhealthy objects. Stimulus pairs were grouped into "congruent" (olfactory and visual presentation of the same object), "semi-congruent" (stimuli of similar "healthiness"), and "incongruent" (healthy-unhealthy stimulus combination). Using functional magnetic resonance imaging and psychophysiological interaction (PPI) analyses, we revealed part of a neural network, the nodes of which show differential connectivity depending on the level of congruency of the presented stimulus combinations. This network relies strongly on, mostly left, inferior frontal gyrus. The analysis of such network transcends standard subtractive designs and indicates the need for more detailed formulations of neuronal models and increased specificity in functional imaging.

Cognitive Load Alters Neuronal Processing of Food Odors.

Obesity is a major health concern in modern societies. Although decreased physical activity and enhanced intake of high-caloric foods are important risk factors for developing obesity, human behavior during eating also plays a role. Previous studies have shown that distraction while eating increases food intake and leads to impaired processing of food stimuli. As olfaction is the most important sense involved in flavor perception, we used functional magnetic resonance imaging techniques to investigate the influence of cognitive memory load on olfactory perception and processing. Low- and high-caloric food odors were presented in combination with either low or high cognitive loads utilizing a memory task. The efficacy of the memory task was verified by a decrease in participant recall accuracy and an increase in skin conductance response during high cognitive load. Our behavioral data reveal a diminished perceived intensity for low- but not high-caloric food odors during high cognitive load. For low-caloric food odors, bilateral orbitofrontal (OFC) and piriform cortices (pirC) showed significantly lower activity during high compared with low cognitive load. For high-caloric food odors, a similar effect was established in pirC, but not in OFC. Insula activity correlates with higher intensity ratings found during the low cognitive load condition. We conclude lower activity in pirC and OFC to be responsible for diminished intensity perception, comparable to results in olfactory impaired patients and elderly. Further studies should investigate the influence of olfactory/gustatory intensities on food choices under distraction with special regards to low-caloric food.