Chronic Stress Remodels Synapses in an Amygdala Circuit–Specific Manner

Background

Chronic stress exposure increases the risk of developing various neuropsychiatric illnesses. The behavioral sequelae of stress correlate with dendritic hypertrophy and glutamate-related synaptic remodeling at basolateral amygdala projection neurons (BLA PNs). Yet, though BLA PNs are functionally heterogeneous with diverse corticolimbic targets, it remains unclear whether stress differentially impacts specific output circuits.

Butane detection after long-term treatment of burns in two autopsy cases

A man and a woman were rescued from a room that had exploded. Many empty cassette gas cylinders were found in the room. The man and woman were hospitalized immediately for the treatment of burns. The woman died 6 days later, and the man died 31 days later without regaining consciousness. Carbonization and hardening of the frontal facial skin and parts of the left and right fingers were observed on the man's body. In both cases, systemic burns had led to progressive systemic edema and markedly suppressed circulation. Analytical samples for butanes obtained from their bodies at autopsy were stored at −20 °C for 14 and 25 days, respectively, before analysis. Normal butane and isobutane were quantified in the brain and subcutaneous adipose tissue of the woman. Only the isobutane was quantified in the adipose tissue of the man. The evidence suggests that the man lit a cigarette while breathing gas and the entire room exploded. Our results also suggest that butane can be detected in the adipose tissue of autopsy cases long after inhalation even under the present storage conditions, and isobutane may remain in adipose tissue longer than n-butane.     

脑淀粉样血管病发病机制的研究进展

脑淀粉样血管病（cerebral amyloid angiopathy，CAA）的主要致病物质是β淀粉样蛋白，其 产生异常、清除障碍导致异常沉积，引起管壁破坏、管腔狭窄等病理变化，最终导致CAA。目前CAA的 具体发病机制尚不清楚，涉及的成分复杂。本文介绍了β淀粉样蛋白产生及清除的三种过程及其平 衡破坏的后续效应和主要影响因素，同时从病因分类的角度阐明CAA的类型。     

Chronic brain stimulation rewarding experience ameliorates depression-induced cognitive deficits and restores aberrant plasticity in the prefrontal cortex

Background

Major depressive disorder (MDD) is a multifactorial disease which often coexists with cognitive deficits. Depression-induced cognitive deficits are known to be associated with aberrant reward processing, neurochemical and structural alterations. Recent studies have shown that chronic electrical stimulation of brain reward areas induces a robust antidepressant effect. However, the effects of repeated electrical self-stimulation of lateral hypothalamus - medial forebrain bundle (LH-MFB) on depression-induced cognitive deficits and associated neurochemical and structural alterations in the prefrontal cortex (PFC) are unknown.

Trunk and pelvis biomechanical responses in children with cerebral palsy and with typical development during horseback riding

BackgroundChildren with cerebral palsy (CP) have poor postural control. Horseback riding (HR) is an alternative treatment shown to improve postural control among children with CP. However, there is a paucity of research investigating the underlying mechanisms responsible for improving postural control during HR.Research questionWhat are the three-dimensional biomechanical responses of the trunk and pelvis during HR among children with CP and with typical development (TD)?MethodsThe participants, aged 4–12 years old, were inexperienced horseback riders, consisting of 10 children with TD and 10 children with spastic diplegia CP (SDCP) with GMFCS level III. Participants donned inertial measurement units (IMU) on their trunk and pelvis in order to measure angular displacement and velocity. An additional IMU was placed on the horse’s lumbosacral joint. The mean absolute relative phase (MARP) and deviation phase (DP) were calculated from each plane of movement for the angular displacement and velocity across the gait cycle of the horse. Differences between groups were analyzed using independent t-tests.ResultsThe MARP in the frontal plane was lower in the SDCP group, when compared to the TD group (p = 0.01). Additionally, no differences were found between groups for the DP along all three axes. However, the TD group demonstrated greater pelvic movement variability in relation to the horse’s pelvis movement, when compared to the SDCP group.SignificanceChildren with SDCP demonstrated an in-phase coupling pattern with decreased variability of pelvic movement in relation to the horse’s pelvis.     

Long-term effects of concussion on relevancy-based modulation of somatosensory-evoked potentials

ObjectiveThe purpose of this investigation was to better understand the effects of concussions on the ability to selectively up or down-regulate incoming somatosensory information based on relevance.MethodsMedian nerve somatosensory-evoked potentials (SEPs) were elicited from electrical stimulation and recorded from scalp electrodes while participants completed tasks that altered the relevance of specific somatosensory information being conveyed along the stimulated nerve.ResultsWithin the control group, SEP amplitudes for task-relevant somatosensory information were significantly greater than for non-relevant somatosensory information at the earliest cortical processing potentials (N20-P27). Alternatively, the concussion history group showed similar SEP amplitudes for all conditions at early processing potentials, however a pattern similar to controls emerged later in the processing stream (P100) where both movement-related gating and facilitation of task-relevant information were present.ConclusionsPreviously concussed participants demonstrated impairments in the ability to up-regulate relevant somatosensory information at early processing stages. These effects appear to be chronic, as this pattern was observed on average several years after participants’ most recent concussion.SignificanceGiven the role of the prefrontal cortex in relevancy-based facilitation during movement-related gating, these findings lend support to the notion that this brain area may be particularly vulnerable to concussive forces.     

Social media use and the not-so-imaginary audience: Behavioral and neural mechanisms underlying the influence on self-concept

We investigated behavioral and neural mechanisms in the relation between social media use (SMU) and self-concept, as well as longitudinal developmental outcomes. Adolescents and young adults (N = 150, 11–21 years old at T1) rated themselves on 60 traits in the academic, physical and prosocial domain, and also indicated how they thought peers would judge them (reflected-peer-judgements). Longitudinal questionnaires (1- and 2-year follow-up) were collected to assess positive (prosocial behavior, self-concept clarity) and negative (clinical symptoms) long-term outcomes.Results indicated that heavier self-reported SMU was linked with lower difference scores between self-judgements and reflected-peer-judgements. Lower SMU was related to more positive ratings from self-judgements vs. reflected-peer-judgements. SMU was also associated with less positive self-concept, particularly in the academic domain (boys and girls) and physical domain (girls). Neurally, increased SMU was linked to heightened mPFC-activity during self-judgements compared to reflected-peer-judgements, and increased activity during physical compared to academic and prosocial self-judgements. Longitudinal analyses indicated no evidence for long-term effects of social media use, self/reflected-peer-difference scores and mPFC-activity on clinical symptoms, prosocial behavior or self-concept clarity. This study highlights the complex relationship between social media use and wellbeing and future research is needed to confirm the lack of long-term effects.     

Meta-analysis of brain structural changes after electroconvulsive therapy in depression

BackgroundIncreases in the volume of the amygdala and hippocampus after electroconvulsive therapy (ECT) are among the most robust effects known to the brain-imaging field. Recent advances in the segmentation of substructures of these regions allow for novel insights on the relationship between brain structure and clinical outcomes of ECT.ObjectiveWe aimed to provide a comprehensive synthesis of evidence available on changes in brain structure after ECT, including recently published data on hippocampal subfields.MethodsA meta-analysis of published studies was carried out using random-effects models of standardized mean change of regional brain volumes measured with longitudinal magnetic resonance imaging of depressive patients before and after a series of ECT.ResultsData from 21 studies (543 depressed patients) were analysed, including 6 studies (118 patients) on hippocampal subfields. Meta-analyses could be carried out for seven brain regions for which data from at least three published studies was available. We observed increases in left and right hippocampi, amygdalae, cornua ammonis (CA) 1, CA 2/3, dentate gyri (DG) and subicula with standardized mean change scores ranging between 0.34 and 1.15. The model did not reveal significant volume increases in the caudate. Meta-regression indicated a negative relationship between the reported increases in the DG and relative symptom improvement (−0.27 (SE: 0.09) per 10%).ConclusionsECT is accompanied by significant volume increases in the bilateral hippocampus and amygdala that are not associated with treatment outcome. Among hippocampal subfields, the most robust volume increases after ECT were measured in the dentate gyrus. The indicated negative correlation of this effect with antidepressant efficacy warrants replication in data of individual patients.     

Hip Displacement in Cerebral Palsy: The Role of Surveillance

IntroductionHip displacement is common in cerebral palsy (CP) and is related to the severity of neurological and functional impairment. It is a silent, but progressive disease, and can result in significant morbidity and decreased quality of life, if left untreated. The pathophysiology of hip displacement in CP is a combination of hip flexor-adductor muscle spasticity, abductor muscle weakness, and delayed weight-bearing, resulting in proximal femoral deformities and progressive acetabular dysplasia. Due to a lack of symptoms in the early stages of hip displacement, the diagnosis is easily missed. Awareness of this condition and regular surveillance by clinical examination and serial radiographs of the hips are the key to early diagnosis and treatment.Hip surveillance programmesSeveral population-based studies from around the world have demonstrated that universal hip surveillance in children with CP allows early detection of hip displacement and appropriate early intervention, with a resultant decrease in painful dislocations. Global hip surveillance models are based upon the patients’ age, functional level determined by the Gross Motor Function Classification system (GMFCS), gait classification, standardized clinical exam, and radiographic indices such as the migration percentage (MP), as critical indicators of progressive hip displacement.ConclusionDespite 25 years of evidence showing the efficacy of established hip surveillance programmes, there is poor awareness among healthcare professionals in India about the importance of regular hip surveillance in children with CP. There is a need for professional organizations to develop evidence-based guidelines for hip surveillance which are relevant to the Indian context.