Aggression and brain asymmetries: A theoretical review

Abstract

The relationship between aggression and brain asymmetries has not been studied enough. The association between both concepts can be approached from two different perspectives. One perspective points to brain asymmetries underlying the emotion of anger and consequently aggression in normal people. Another one is concerned with the existence of brain asymmetries in aggressive people (e.g., in the case of suicides or psychopathies). Research on emotional processing points out the confusion between emotional valence (positive-negative) and motivational direction (approach-withdrawal). Because of this, it is not clear whether the frontal asymmetry reflects the valence of the emotion, the direction of the motivation, or a combination of valence and motivation. Appetitive motivations are not always associated with positive affects. Anger (a negative emotion) has been associated with approach motivation and with aggression. Relative left-prefrontal activity is associated with state anger and with aggression. This information would lead to the conclusion that the more violent a culture, the higher the relative proportion of the right-handers. On the other side, there is an exaggerated structural asymmetry in the anterior hippocampus (R>L) in unsuccessful psychopaths. In suicidal persons, the functional insufficiency of the right hemisphere produces a compensatory shift to left hemisphere information processing, showing a reversed asymmetry of typical traits for suicidal people. These findings suggest, therefore, the existence of a certain correlation between brain asymmetries and human aggression.

How Elephants are Opening Doors: Developmental Neuroethology, Attachment and Social Context

“…loss of mother and allomothers, premature weaning, witness to family deaths, herd dissolution, translocation; ) during periods when critical patterning of brain development occurs (Schore 2003a). Neurobiologically, their hyper-aggression is consistent with an intense state of amygdala-hypothalamic sympathetic hyperarousal and a weakened higher right orbitofrontal inhibitory system associated with impaired developmental trauma (Rohlfs & Ramirez 2006). The absence of second phase all-male socialization is also likely to have been a significant factor leading to affective dysregulation.…”

“…2001) during periods when critical patterning of brain development occurs (Schore 2003a). Neurobiologically, their hyper‐aggression is consistent with an intense state of amygdala–hypothalamic sympathetic hyperarousal and a weakened higher right orbitofrontal inhibitory system associated with impaired developmental trauma (Rohlfs & Ramirez 2006).…”

“…asocial and atypical affiliative behaviours) through triggering hyperarousal in the limbic and ANSs that support emotional behaviour. This is biochemically expressed in elevated levels of arousal regulating catecholamines, corticotropinreleasing factor, and corticosteroids and behaviourally in one or more ways: a persistent fearful temperament (Adolphs et al 2004), diminished capacity to modulate memory, fear, and social judgement (Morris, Ohman & Dolan 1999), a predisposition to aggression dysregulation and violence (Rohlfs & Ramirez 2006), and post-traumatic stress disorder (PTSD; Schore 2003a). Resulting impairment of socio-affective circuits, especially in higher cortical regions, underlies many abnormal and inappropriate emotional responses that express at later stages of life (Poeggel et al 2005).…”

History, development and current advances concerning the evolutionary roots of human right‐handedness and language: Brain lateralisation and manual laterality in non‐human primates

“…These differences between hierarchical statuses were assumed to be the consequence of higher levels of psychosocial stress (e.g., competition for access to food and space) experienced by subordinates leading to greater right‐hand use. The possibility that stress could elicit a right‐side bias at the population level is supported by several studies (chimpanzees: Prieur et al, ; Prieur et al, ; gorillas: Prieur, Pika, Barbu, & Blois‐Heulin, ; rats: e.g., Alonso, Castellano, & Rodriguez, ; Castellano, Diaz‐Palarea, Barroso, & Rodriguez, ; Castellano, Diaz‐Palarea, Rodriguez, & Barroso, ; anoles: Deckel, ; see also Rohlfs & Ramirez, for review of reports on humans). According to Barnard, Matthews, Messori, Podaliri‐Vulpiani, and Ferri (), stress due to partial separation would be linked to strength of ewes’ and their lambs’ laterality.…”

Current Status of the Anger Avoidance Model: Recent Empirical Findings and Treatment Considerations

“…A recent study sought to assess this construct by using Gray's Behavioural Inhibition/Behavioural Activation scale [15], but had to remove the measure from analysis due to problems with internal consistency [19]. While other recent studies have utilized the BIS/BAS scales and have found support for the hypothesized relationship between a temperament such as behavioural inhibition and violent behaviour [34,35], future studies will have to carefully choose an appropriate measurement tool for assessing this important construct in concert with emotion regulation and other relevant variables before support for its place in the AAM can be stated. Until then, little can be said beyond the theoretical proposition.…”