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It has recently been theorized that the frontal asymmetry of approach- and avoidance-related motivation is mirrored in the posterolateral cerebellum. Accordingly, left-to-right dominant cerebellar activity is associated with avoidance-related motivation, whereas right-to-left dominant cerebellar activity is associated with approach-related motivation. The aim of this study was to examine the cerebellar asymmetry of motivational direction in approach-related behavior in the context of aggression. In this randomized double-blind sham-controlled crossover study, thirty healthy right-handed adult volunteers received 2 mA active or sham left cathodal-right anodal transcranial direct current stimulation (tDCS) to the cerebellum on two separate occasions while engaging in the Point Subtraction Aggression Paradigm (PSAP) task to measure aggressive behavior. Self-reported state anger was assessed before, halfway and immediately after the task, and heart rate and heart rate variability (HRV) were measured during the task. No main effects of tDCS on aggressive behavior, heart rate and HRV were found. Higher state anger before and during the PSAP task was associated with increased aggressive behavior in the active compared to sham tDCS condition. Aggressive behavior was positively correlated with heart rate during active tDCS, while an inverse association was observed during sham tDCS. Results provide support for the cerebellar asymmetry of motivational direction in approach-related behavior and illustrate the importance of affective state-dependency in tDCS-related effects., (© 2024. The Author(s).)

Children and adolescents with conduct problems participate in Cognitive Behavioral Therapy (CBT), either in individual or group format, in view of learning social problem-solving skills that enable them to behave in more independent and situation-appropriate ways. Parents must support their child's learning processes in everyday life and therefore these processes need attention in CBT sessions in which parents and their child participate. The social problem-solving model of CBT previously described (Matthys & Schutter, Clin Child Fam Psychol Rev 25:552-572, 2022; Matthys & Schutter, Clin Child Fam Psychol Rev 26:401-415, 2023) consists of nine psychological skills. In this narrative review we propose that instead of addressing each skill separately in sessions with both parents and their child, therapists work on three schemas (latent mental structures): (1) goals, (2) outcome expectations, and (3) normative beliefs about aggression. Based on social-cognitive and cognitive neuroscience studies we argue that these three schemas affect five core social problem-solving skills: (1) interpretation, (2) clarification of goals, (3) generations of solutions, (4) evaluation of solutions, and (5) decision-making. In view of tailoring CBT to the individual child's characteristic schemas and associated social problem-solving skills, we suggest that children and adolescents participate in individual sessions with their parents. The therapist uses Socratic questioning in order to find out characteristic schemas of the child, encourage reflection on these schemas, and explore alternative schemas that had previously been outside the child's attention. The therapist functions as a model for parents to ask their child questions about the relevant schemas with a view of achieving changes in the schemas., (© 2024. The Author(s).)

New insights into the functional neuroanatomic correlates of emotions point toward the involvement of the cerebellum in anger and aggression. To identify cerebellar regions commonly activated in tasks examining the experience of anger and threat as well as exerting an aggressive response, two coordinate-based activation likelihood estimation meta-analyses reporting a total of 57 cerebellar activation foci from 819 participants were performed. For anger processing (18 studies), results showed significant clusters in the bilateral posterior cerebellum, overlapping with results from previous meta-analyses on emotion processing, and implying functional connectivity to cognitive, limbic, and social canonic networks in the cerebral cortex. By contrast, active aggression expression (10 studies) was associated with significant clusters in more anterior regions of the cerebellum, overlapping with cerebellar somatosensory and motor regions and displaying functional connectivity with the somatomotor and default mode network. This study not only strengthens the notion that the cerebellum is involved in emotion processing, but also provides the first quantitative evidence for distinct cerebellar functional activation patterns related to anger and aggression., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020. Published by Elsevier Inc.)

Functional neuroimaging studies in adults show that aggression involves reduced brain communication between subcortical and cortical areas dedicated to motivation and control, respectively. Prior research indicates that sex steroid hormone production during adolescence negatively influences the rapid development of white matter connectivity between subcortical and cortical areas during adolescence and may potentiate aggression. Here, we tested this hypothesis in 258 participants between 8 and 25 years of age by using Diffusion Weighted Imaging to examine the microstructure of white matter connections within the fronto-temporal-subcortical network. Trait aggression was measured using the Buss Perry Aggression Questionnaire and testosterone and estradiol levels were measured in saliva. Results indicated that higher levels of testosterone were associated with less white matter integrity within the fronto-temporal-subcortical network (i.e., higher mean diffusivity [MD] longitudinal [LD], and radial diffusivity [RD]). Furthermore, lower fractional anisotropy and higher MD, LD, and RD values within this network increased expressive forms of aggression and reduced inhibited forms of aggression (hostility). Our study indicates higher levels of testosterone relating to lower quality of structural cortical-subcortical connectivity, arguably resulting in a shift from inhibited towards expressive forms of aggression. Our data adds evidence to the idea that aggressive tendencies are subcortically driven, but individuals with relatively high testosterone might have lower structural connectivity within cortical control areas, resulting in a stronger tendency to act on these aggressive tendencies., (© 2014 Wiley Periodicals, Inc.)

According to the frontal cortical asymmetry model of motivational direction, anger and aggression are associated with approach motivation and a dominant left frontal hemisphere. Functional interhemispheric connectivity has been proposed as a possible mechanism that could explain the frontal cortical asymmetry of anger and aggression. Reciprocal interactions between the cerebral hemispheres are primarily established by the corpus callosum which is the largest white matter bundle of the human brain. Experimental brain research has now provided evidence for callosal involvement in approach-motivation. In line with the frontal cortical asymmetry model of motivational direction, differences in the direction of interhemispheric signal transfer are proposed to contribute to anger and aggression. It is concluded that the human corpus callosum provides a possible neuroanatomical correlate for frontal cortical asymmetries and that interhemispheric signal transfer plays a role in the emergence of approach-related motivation and behaviour., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Asymmetrical patterns of frontal cortical activity have been implicated in the development and expression of aggressive behavior. Along with individual motivational tendencies, the ability to restrain one's impulses might be a factor in aggressive behavior. Recently, a role for the inhibitory cortical beta rhythm was suggested. The present study investigated whether individual differences in resting state asymmetries in the beta frequency band were associated with trait aggression and behavioral inhibition. In addition, the selective contributions of the prefrontal and motor cortex areas to these associations were examined. Results showed that relative dominant right frontal beta frequency activity was associated with both heightened trait aggression, especially hostility, and reduced response inhibition. Moreover, asymmetries over the anterior electrode locations proved to be related most closely to trait aggression, while asymmetries over the central electrode locations were associated with response inhibition. Together these findings show that right-dominant frontal beta activity is positively associated with aggressive tendencies and reduced behavioral inhibition.

The relationship between anger and aggression is imperfect. Based on work on the neuroscience of anger, we predicted that anger associated with greater relative left frontal cortical activation would be more likely to result in aggression. To test this hypothesis, we combined transcranial direct current stimulation (tDCS) over the frontal cortex with interpersonal provocation. Participants received insulting feedback after 15 min of tDCS and were able to aggress by administering noise blasts to the insulting participant. Individuals who received tDCS to increase relative left frontal cortical activity behaved more aggressively when they were angry. No relation between anger and aggression was observed in the increase relative right frontal cortical activity or sham condition. These results concur with the motivational direction model of frontal asymmetry, in which left frontal activity is associated with anger. We propose that anger with approach motivational tendencies is more likely to result in aggression., (© The Author (2011). Published by Oxford University Press.)

The psychobiological basis of reactive aggression, a condition characterized by uncontrolled outbursts of socially violent behavior, is unclear. Nonetheless, several theoretical models have been proposed that may have complementary views about the psychobiological mechanisms involved. In this review, we attempt to unite these models and theorize further on the basis of recent data from psychological and neuroscientific research to propose a comprehensive neuro-evolutionary framework: The Triple Imbalance Hypothesis (TIH) of reactive aggression. According to this model, reactive aggression is essentially subcortically motivated by an imbalance in the levels of the steroid hormones cortisol and testosterone (Subcortical Imbalance Hypothesis). This imbalance not only sets a primal predisposition for social aggression, but also down-regulates cortical-subcortical communication (Cortical-Subcortical Imbalance Hypothesis), hence diminishing control by cortical regions that regulate socially aggressive inclinations. However, these bottom-up hormonally mediated imbalances can drive both instrumental and reactive social aggression. The TIH suggests that reactive aggression is differentiated from proactive aggression by low brain serotonergic function and that reactive aggression is associated with left-sided frontal brain asymmetry (Cortical Imbalance Hypothesis), especially observed when the individual is socially threatened or provoked. This triple biobehavioral imbalance mirrors an evolutionary relapse into violently aggressive motivational drives that are adaptive among many reptilian and mammalian species, but may have become socially maladaptive in modern humans.

An aggressive personality style has been proposed to arise from a cortical asymmetry between the left and right frontal hemispheres. In the present transcranial magnetic stimulation (TMS) study, evidence was sought for a link between an aggressive personality style and functional interhemispheric connectivity between the left and right frontal cortices. Functional interhemispheric connectivity was measured by determining transcallosal inhibition (TCI) using TMS in 20 healthy right-handed volunteers, who were given the Buss-Perry Aggression Questionnaire (AQ) and a selective attention task. Analyses showed higher levels of left-to-right TCI significantly correlated with higher AQ scores. Furthermore, increased left-to-right together with reduced right-to-left TCI was associated with a stronger attentional bias for angry faces. This is the first study to provide a biological mechanism underlying the asymmetry between left and right frontal cortex activity in human aggression. We conclude that an aggressive personality style and selective attention to angry faces are positively correlated with functional interhemispheric connectivity.

Background: Post-traumatic stress disorder (PTSD), anxiety, and impulsive aggression are linked to transdiagnostic neurocognitive deficits. This includes impaired inhibitory control over inappropriate responses. Prior studies showed that inhibitory control can be improved by modulating the right inferior frontal gyrus (IFG) with transcranial direct current stimulation (tDCS) in combination with inhibitory control training. However, its clinical potential remains unclear. We therefore aimed to replicate a tDCS-enhanced inhibitory control training in a clinical sample and test whether this reduces stress-related mental health symptoms. Methods: In a preregistered double-blind randomized-controlled trial, 100 active-duty military personnel and post-active veterans with PTSD, anxiety, or impulsive aggression symptoms underwent a 5-session intervention where a stop-signal response inhibition training was combined with anodal tDCS over the right IFG for 20 min at 1.25 mA. Inhibitory control was evaluated with the emotional go/no-go task and implicit association test. Stress-related symptoms were assessed by self-report at baseline, post-intervention, and after 3-months and 1-year follow-ups. Results: Active relative to sham tDCS neither influenced performance during inhibitory control training nor on assessment tasks, and did also not significantly influence self-reported symptoms of PTSD, anxiety, impulsive aggression, or depression at post-assessment or follow-up. Conclusions: Our results do not support the idea that anodal tDCS over the right IFG at 1.25 mA enhances response inhibition training in a clinical sample, or that this tDCS-training combination can reduce stress-related symptoms. Applying different tDCS parameters or combining tDCS with more challenging tasks might provide better conditions to modulate cognitive functioning and stress-related symptoms. [ABSTRACT FROM AUTHOR]