Within amygdala: Basolateral parts are selectively impaired in premature-born adults

Neonatal amygdala volumes, procedural pain and the association with social-emotional development in children born very preterm

Very preterm birth (< 32 weeks' gestational age) is associated with later social and emotional impairments, which may result from enhanced vulnerability of the limbic system during this period of heightened vulnerability. Evidence suggests that early procedural pain may be a key moderator of early brain networks. In a prospective cohort study, neonates born very preterm (< 30 weeks' gestation) underwent MRI scanning at term-equivalent age (TEA) and clinical data were collected (mechanical ventilation, analgesics, sedatives). Procedural pain was operationalized as the number of skin breaking procedures. Amygdala volumes were automatically extracted. The Strengths and Difficulties questionnaire was used to assess social-emotional outcomes at 5 years of age (mean age 67.5 months). General linear models were employed to examine the association between neonatal amygdala volumes and social-emotional outcomes and the timing and amount of procedural pain exposure (early within the first weeks of life to TEA) as a moderator, adjusting for biological sex, gestational age, 5-year assessment age, days of mechanical ventilation and total cerebral volumes. A total of 42 preterm infants participated. Right amygdala volumes at TEA were associated with prosocial behaviour at age 5 (B = -0.010, p = 0.005). Procedural pain was found to moderate the relationship between right amygdala volumes in the neonatal period and conduct problems at 5 years, such that early skin breaking procedures experienced within the first few weeks of life strengthened the association between right amygdala volumes and conduct problems (B = 0.005, p = 0.047). Late skin breaking procedures, experienced near TEA, also strengthened the association between right amygdala volumes and conduct problems (B = 0.004, p = 0.048).

Amygdala structure and function and its associations with social-emotional outcomes in a low-risk preterm sample

Amygdala atypical volume development and functional connectivity (FC) at small gestational ages (GA) have been found across childhood. This adult-oriented study assesses whether altered amygdala structure and function is present following low-risk preterm birth. T1-weighted and resting-state functional MRI images of 33 low-risk preterm (30-36 weeks' GA) and 29 full-term (37-42 weeks' GA) young adults of both sexes, aged between 20 and 32 years old, were analyzed using FreeSurfer (v6.0.0) and Coon Toolbox (v21.a). The social-emotional assessment included Happé's Strange Stories Test, the Moral Judgment Test, Delay-Discounting Test, Adult Self Report, and Emotion Regulation Questionnaire. No differences were found in social-emotional outcomes or amygdala volumes between the groups. Low-risk preterm young adults showed increased FC between the left amygdala, right amygdala and medial frontal cortex (MedFC) (F = 9.89, p-FWE = 0.009) at cluster level compared to their full-term peers. However, significant results at connection level were not observed between left and right amygdala. Lastly, increased FC at cluster level between the right amygdala and MedFC, and left amygdala and MedFC, was related to better social-emotional outcomes only in low-risk preterm young adults (F = 6.60, p-FWE = 0.036) at cluster level. At connection level, in contrast, only right amygdala-MedFC increased FC was significantly associated with better social-emotional outcomes. This study reveals that low-risk prematurity does not have an effect on social-emotional outcomes or structural amygdala volumes during young adulthood. However, individuals who were considered to be at a lower risk of exhibiting neurodevelopmental alterations following preterm birth demonstrated increased FC between the left and right amygdala and MedFC.

Emotional Regulation Interventions on Developmental Course for Preterm Children: A Systematic Review of Randomized Control Trials

Children born preterm (<37 weeks of gestation) are at increased risk of socio-emotional difficulties. This study aims to determine the effects of rehabilitation intervention on the emotional regulation of children born preterm through a systematic review. We conducted a systematic review according to PRISMA guidelines. The literature screening was carried out on PUBMED, SCOPUS and WEB OF SCIENCE in August 2022. An author identified eligible studies based on predefined inclusion criteria and extracted the data. RCT quality was assessed using the JADAD and PEDro scales. We selected five RCTs for qualitative synthesis, having the common objective of evaluating the changes in emotional regulation after a rehabilitation intervention. Evidence of benefits was found after parent training intervention (PCIT; p < 0.05). Moreover, there was an improvement in day-to-day executive life and fewer behavioral problems after mindfulness intervention. Clinical, but not statistical, efficacy was found for the group-based physiotherapy intervention. In conclusion, parent training and mindfulness interventions can be helpful rehabilitation techniques, but the relatively small sample limited statistical power, so the discovery needs to be interpreted cautiously. Further research on these aspects is recommended.

Amygdala subnuclear volumes in temporal lobe epilepsy with hippocampal sclerosis and in non-lesional patients

Together with hippocampus, the amygdala is important in the epileptogenic network of patients with temporal lobe epilepsy. Recently, an increase in amygdala volumes (i.e. amygdala enlargement) has been proposed as morphological biomarker of a subtype of temporal lobe epilepsy patients without MRI abnormalities, although other data suggest that this finding might be unspecific and not exclusive to temporal lobe epilepsy. In these studies, the amygdala is treated as a single entity, while instead it is composed of different nuclei, each with peculiar function and connection. By adopting a recently developed methodology of amygdala’s subnuclei parcellation based of high-resolution T₁-weighted image, this study aims to map specific amygdalar subnuclei participation in temporal lobe epilepsy due to hippocampal sclerosis (n = 24) and non-lesional temporal lobe epilepsy (n = 24) with respect to patients with focal extratemporal lobe epilepsies (n = 20) and healthy controls (n = 30). The volumes of amygdala subnuclei were compared between groups adopting multivariate analyses of covariance and correlated with clinical variables. Additionally, a logistic regression analysis on the nuclei resulting statistically different across groups was performed. Compared with other populations, temporal lobe epilepsy with hippocampal sclerosis showed a significant atrophy of the whole amygdala (p_Bonferroni = 0.040), particularly the basolateral complex (p_Bonferroni = 0.033), while the non-lesional temporal lobe epilepsy group demonstrated an isolated hypertrophy of the medial nucleus (p_Bonferroni = 0.012). In both scenarios, the involved amygdala was ipsilateral to the epileptic focus. The medial nucleus demonstrated a volume increase even in extratemporal lobe epilepsies although contralateral to the seizure onset hemisphere (p_Bonferroni = 0.037). Non-lesional patients with psychiatric comorbidities showed a larger ipsilateral lateral nucleus compared with those without psychiatric disorders. This exploratory study corroborates the involvement of the amygdala in temporal lobe epilepsy, particularly in mesial temporal lobe epilepsy and suggests a different amygdala subnuclei engagement depending on the aetiology and lateralization of epilepsy. Furthermore, the logistic regression analysis indicated that the basolateral complex and the medial nucleus of amygdala can be helpful to differentiate temporal lobe epilepsy with hippocampal sclerosis and with MRI negative, respectively, versus controls with a consequent potential clinical yield. Finally, the present results contribute to the literature about the amygdala enlargement in temporal lobe epilepsy, suggesting that the increased volume of amygdala can be regarded as epilepsy-related structural changes common across different syndromes whose meaning should be clarified.

Eye Gaze in Autism Spectrum Disorder: A Review of Neural Evidence for the Eye Avoidance Hypothesis

Reduced eye contact early in life may play a role in the developmental pathways that culminate in a diagnosis of autism spectrum disorder. However, there are contradictory theories regarding the neural mechanisms involved. According to the amygdala theory of autism, reduced eye contact results from a hypoactive amygdala that fails to flag eyes as salient. However, the eye avoidance hypothesis proposes the opposite-that amygdala hyperactivity causes eye avoidance. This review evaluated studies that measured the relationship between eye gaze and activity in the 'social brain' when viewing facial stimuli. Of the reviewed studies, eight of eleven supported the eye avoidance hypothesis. These results suggest eye avoidance may be used to reduce amygdala-related hyperarousal among people on the autism spectrum.