There is substantial imaging evidence for volumetric abnormalities of the amygdala in younger children with autism spectrum disorder (ASD). The amygdala can be divided into functionally distinct laterobasal, superficial, and centromedial subregions. To date, we are not aware of any in vivo reports specifically assessing subregional amygdalar abnormalities in individuals with ASD.
To evaluate alterations in subregional amygdalar morphology in children with ASD compared with typically developing (TD) children and to examine the relationships with ASD symptom severity.
A cross-sectional study encompassing a narrow age range of children with ASD and age-matched TD children that evaluated magnetic resonance imaging-defined subregional morphology of the amygdala using a novel subregional analytic method.
Participants were recruited and clinically evaluated through the University of Washington Autism Center and imaged at the Diagnostic Imaging Sciences Center at the University of Washington. Imaging data were analyzed through the Brain Imaging Laboratory at the Seoul National University.
Fifty-one children 6 to 7 years of age (ASD, n = 31 and TD, n = 20) were assessed using magnetic resonance imaging and behavioral measures.
Volume and subregional measures of the amygdala and measures of social and communication functioning.
The ASD group exhibited larger right and left amygdalae, by 12.7% and 11.0%, respectively, relative to the TD group. Subregional analysis revealed that the ASD group had enlarged laterobasal amygdalar subregions, relative to the TD group, after adjusting for age, sex, and hemispheric cerebral volume (P < .05, false discovery rate corrected and with clustered surface points >15). Exploratory analyses revealed that there were linear trends comparing a strictly defined subgroup of children with autistic disorder, who exhibited the greatest extent of laterobasal enlargement, followed by a subgroup of children with pervasive developmental disorder not otherwise specified and then the group of TD children (P for linear trend <.001). There were linear trends between enlargement of laterobasal subregions and lower levels of social and communication functioning (P < .001, P < .001, and P = .001 for 3 areas in the right laterobasal subregion; P < .001 for 1 area in the left laterobasal subregion).
The current study demonstrates bilateral enlargement of laterobasal subregions of the amygdala in 6- to 7-year-old children with ASD and that subregional alterations are associated with deficits in social and communicative behavior.
"The amygdala is supposed to play a central role in the etiopathology of ASDs and several theoretical explanations compatible with the amygdala dysfunction have been proposed to account for socio-emotional impairments, including abnormal eye contact, poor recognition of fear and other negative emotions, face processing, mental state understanding and empathy (Baron-Cohen et al., 2000; Amaral, Bauman & Schumann, 2003; Ashwin et al., 2006; Kim et al., 2010; Kliemann et al., 2012). As posit by the " Relevance Detection Theory " (Sander, Grafman & Zalla, 2003), the human amygdala is a component of this extended neural cortico-limbic system involved in detecting stimuli by focusing attentional and physiological resources on cues that have special relevance for the safety or success of an organism within the broader context of its social life. "
[Show abstract][Hide abstract] ABSTRACT: Impairments in emotional processing in Autism Spectrum Disorders (ASDs) can be characterised by failure to generate and recognize self-reflective, cognitive-based emotions, such as pride, embarrassment and shame. Among this type of emotions, regret and disappointment, as well as their positive counterparts, result from a counterfactual comparison, that is the comparison between an actual value (“what is”) and a fictive value (“what might have been”). However, while disappointment is experienced when the obtained outcome is worse than the expected outcome that might have occurred from the same choice, regret occurs when one experiences an outcome that is worse than the outcome of foregone choices. By manipulating a simple gambling task, we examined subjective reports on the intensity of negative and positive emotions in a group of adults with High Functioning Autism or Asperger syndrome (HFA/AS), and a control group matched for age, gender and educational level. Participants were asked to choose between two lotteries with different levels of risk under two conditions of outcome feedback: (i) Partial, in which only the outcome of the chosen lottery was visible, (ii) Complete, in which the outcomes of the two lotteries were simultaneously visible. By comparing partial and complete conditions, we aimed to investigate the differential effect between disappointment and regret, as well as between their positive counterparts. Relative to the control participants, the group with HFA/AS reported reduced regret and no difference between regret and disappointment, along with a preserved ability to use counterfactual thinking and similar choice behavior. Difficulties to distinguish the feeling of regret in participants with HFA/AS can be explained by diminished emotional awareness, likely associated with an abnormal fronto-limbic connectivity.
"In adult and animal studies both the BLA and CMA play a pivotal role in numerous emotion-related functions. Specifically, the CMA is thought to be critical for controlling the expression of fear (Qin et al., 2012) whereas the BLA is thought to play a critical role in perception , appraisal, and regulation of emotionally salient stimuli (Kim et al., 2010a). Thus, we hypothesized that activity in both the BLA and CMA would be modulated by CER. "
[Show abstract][Hide abstract] ABSTRACT: When used effectively, cognitive reappraisal of distressing events is a highly adaptive cognitive emotion regulation (CER) strategy, with impairments in cognitive reappraisal associated with greater risk for psychopathology. Despite extensive literature examining the neural correlates of cognitive reappraisal in healthy and psychiatrically ill adults, there is a dearth of data to inform the neural bases of CER in children, a key gap in the literature necessary to map the developmental trajectory of cognitive reappraisal. In this fMRI study, psychiatrically healthy schoolchildren were instructed to use cognitive reappraisal to modulate their emotional reactions and responses of negative affect after viewing sad photos. Consistent with the adult literature, when actively engaged in reappraisal compared to passively viewing sad photos, children showed increased activation in the vlPFC, dlPFC, and dmPFC as well as in parietal and temporal lobe regions. When children used cognitive reappraisal to minimize their experience of negative affect after viewing sad stimuli they exhibited dampened amygdala responses. Results are discussed in relation to the importance of identifying and characterizing neural processes underlying adaptive CER strategies in typically developing children in order to understand how these systems go awry and relate to the risk and occurrence of affective disorders.
"Interestingly, a correlation between the severity of core ASD symptoms and amygdala anatomy has been detected in several studies, with a different trajectory in accordance to age. Indeed, a direct correlation between amygdala volumes and degree of social and communicative impairment has been found in toddlers (Munson et al. 2006; Schumann et al. 2009), and younger children with ASD (Kim et al. 2010). In contrast , smaller amygdalae associated with deficits of social reciprocity in older ASD children (Nacewitz et al. 2006) and with restricted-repetitive behaviour in adult subjects with Asperger syndrome (Dziobek et al. 2006). "
[Show abstract][Hide abstract] ABSTRACT: This brief review encompasses the key findings of structural Magnetic Resonance Imaging (sMRI) research on amygdala volume in autism spectrum disorders (ASD). We also highlight the possible correlation between the autistic behavioural phenotype and amygdala alteration.
Oana Carmen Dragăn, Alexandru Ștefan Fărcășanu, Radu Septimiu Câmpian, Romulus Valeriu Flaviu Turcu
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