Brain structure Sample Clauses

Brain structure. 1.5.1 Brain abnormalities in individuals exposed to childhood maltreatment Brain maturation is a complex topographically distributed process that spans across decades, involving coordinated changes over time in structures (e.g. thinning of the cortex, increasing white matter volume), along with fine-tuning of the network (e.g. changes in connectivity, optimisation of the connections). Thus it is not surprising that exposure to stressors that can overwhelm the capability of an individual to cope can negatively influence this finely regulated process, with widespread impact on cellular metabolism, release of neurotransmitters and developmental trajectories (X. Xx Xxxxxx et al., 2011). Animal models show that increased levels of stress decrease neuronal branching and induce apoptosis in the prefrontal cortex, hippocampus and hypothalamus with a corresponding reduction in grey matter volume, mainly through the rise in corticosteroid concentrations and an overactivation of the noradrenergic system (Xxxxx & Xxxxxx, 2015). The same rat and mouse models show that attempts to cope with those stressors can lead to over-activation in areas of the brain that regulate emotions (i.e. amygdala, prefrontal cortex) or neurotransmitter systems (i.e. serotonin, dopamine), inducing abnormal behaviours (i.e. pathological aggression) (Xxxxx & Xxxxxx, 2015). Interestingly, the first gene-environment interaction study in humans found that the polymorphism of an enzyme involved in the metabolism of dopamine (MAO-A) modulates the likelihood that children exposed to early maltreatment would developed an antisocial behaviour (Xxxxx et al., 2002). In addition, the over-activation of the amygdala in response to negative emotions is a well replicated finding in individuals with a history of abuse (Xxxxxxxxxx et al., 2012). Furthermore, human studies confirm a widespread effect of trauma in brain regions at the interface between the incoming sensory information and the appraisal process, such as the limbic brain structures hippocampus and amygdala as well as the prefrontal cortex (xx Xxxxx et al., 2005). Children exposed to maltreatment show reduced grey matter volume in the medial orbitofrontal cortex, and a reduction in cortical thickness in an extended cluster that incorporates the anterior cingulate, superior frontal gyrus, and orbitofrontal cortex, accompanied by reduced local gyrification within the lingual gyrus and the insula (Xxxxx et al. 2013; Xx Xxxxx et al. 2013). These alter...