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Little is known about the neural correlates of dissociative amnesia, a transdiagnostic symptom mostly present in the dissociative disorders and core characteristic of dissociative identity disorder (DID). Given the vital role of the hippocampus in memory, a prime candidate for investigation is whether total and/or subfield hippocampal volume can serve as biological markers of dissociative amnesia.
A total of 75 women, 32 with DID and 43 matched healthy controls (HC), underwent structural magnetic resonance imaging (MRI). Using Freesurfer (version 6.0), volumes were extracted for bilateral global hippocampus, cornu ammonis (CA) 1–4, the granule cell molecular layer of the dentate gyrus (GC-ML-DG), fimbria, hippocampal−amygdaloid transition area (HATA), parasubiculum, presubiculum and subiculum. Analyses of covariance showed volumetric differences between DID and HC. Partial correlations exhibited relationships between the three factors of the dissociative experience scale scores (dissociative amnesia, absorption, depersonalisation/derealisation) and traumatisation measures with hippocampal global and subfield volumes.
Hippocampal volumes were found to be smaller in DID as compared with HC in bilateral global hippocampus and bilateral CA1, right CA4, right GC-ML-DG, and left presubiculum. Dissociative amnesia was the only dissociative symptom that correlated uniquely and significantly with reduced bilateral hippocampal CA1 subfield volumes. Regarding traumatisation, only emotional neglect correlated negatively with bilateral global hippocampus, bilateral CA1, CA4 and GC-ML-DG, and right CA3.
We propose decreased CA1 volume as a biomarker for dissociative amnesia. We also propose that traumatisation, specifically emotional neglect, is interlinked with dissociative amnesia in having a detrimental effect on hippocampal volume.
Nonsuicidal self-injury (NSSI) is prevalent among adolescents and research is needed to clarify the mechanisms which contribute to the behavior. Here, the authors relate behavioral neurocognitive measures of impulsivity and compulsivity to repetitive and sporadic NSSI in a community sample of adolescents.
Computerized laboratory tasks (Affective Go/No-Go, Cambridge Gambling Task, and Probabilistic Reversal Task) were used to evaluate cognitive performance. Participants were adolescents aged 15 to 17 with (n = 50) and without (n = 190) NSSI history, sampled from the ROOTS project which recruited adolescents from secondary schools in Cambridgeshire, UK. NSSI was categorized as sporadic (1-3 instances per year) or repetitive (4 or more instances per year). Analyses were carried out in a series of linear and negative binomial regressions, controlling for age, gender, intelligence, and recent depressive symptoms.
Adolescents with lifetime NSSI, and repetitive NSSI specifically, made significantly more perseverative errors on the Probabilistic Reversal Task and exhibited significantly lower quality of decision making on the Cambridge Gambling Task compared to no-NSSI controls. Those with sporadic NSSI did not significantly differ from no-NSSI controls on task performance. NSSI was not associated with behavioral measures of impulsivity.
Repetitive NSSI is associated with increased behavioral compulsivity and disadvantageous decision making, but not with behavioral impulsivity. Future research should continue to investigate how neurocognitive phenotypes contribute to the onset and maintenance of NSSI, and determine whether compulsivity and addictive features of NSSI are potential targets for treatment.
Voluntary selection between response alternatives belong to cognitive abilities controlling and regulating goal-directed behaviour. Voluntary selection processes are associated with increased neural activity, especially in medial and lateral frontal brain regions as well as the inferior parietal gyrus. However, the precise function of each brain region as well as the spatiotemporal characteristic of the brain regions involved is not yet clear. The aim of the present study was to disentangle distinct aspects of voluntary selection and their underlying neural processes. Hence, event-related potentials (ERPs) and functional MRI data were acquired simultaneously. Brain regions modulated by the task-induced amplitude variation of ERPs (N2, P3) were indentified. The results showed N2-related hemodynamic responses, especially in medial and lateral frontal brain regions. Among other things, medial frontal brain regions are related to conflict monitoring, control of voluntary action and decision making. By contrast, the P3-amplitude proved to be predominantly related to increased BOLD responses in the temporo-parietal junction [TPJ] and lateral frontal brain regions. These brain regions are thought to play a decisive role in an attentional network involved in detecting auditory and visual stimuli.
Overall, the results of the study indicated a whole network of brain regions to be associated with voluntary selection processes. In addition, at least some frontal brain regions seemed to be involved at an earlier stage than temporo-parietal regions, probably indicating a top-down process.
Executive functions comprise various cognitive abilities including the inhibition of prepotent responses and voluntary decisions. Several studies showed medial-frontal activations in tasks with the free selection of responses. The inhibition of prepotent response tendencies seems to be associated with medial frontal as well as lateral frontal BOLD responses. The aim of this simultaneous EEG and fMRI study was to discriminate the neural correlates of behavioural control processes in ADHD.
8 adults with ADHD and 8 matched healthy subjects performed a go/nogo task comprising three different conditions: during the go condition, subjects were instructed to press a response button as fast as possible; during the nogo condition, this response was to be inhibited. In the voluntary selection task participants were allowed to freely decide, whether to press the response button or not.
The fMRI protocol used a gradient-echo EPI pulse sequence. Further analyses were done with using the BrainVoyager software package (Goebel, Maastricht). EEG signals were simultaneously recorded (Brain Products, Munich).
Electrophysiologically, the nogo task and voluntary decision task led to a negative decline especially in fronto-central brain regions (N2) in both groups. Regarding the functional MRI data we found inhibition-associated BOLD responses especially medial-frontal in the pre-SMA and activations in the medial part of BA 8 for the voluntary selection. ADHD patients showed a reduced contribution of frontal brain regions during free responses compared to controls.
The results may indicate that selection processes are related with dysfunctions predominantly in frontal brain regions in ADHD patients.
Neuroimaging studies in adults with borderline personality disorder (BPD) have reported alterations in frontolimbic areas, but cannot differentiate between alterations originating from disease and those occurring as side-effects of medication or other consequences of the disorder.
To provide a clearer picture of the organic origins of BPD, the present study reduced such confounds by examining adolescents in the early stages of the disorder. It also examined the extent to which alterations associated with BPD are specific, or shared more broadly among other psychiatric disorders.
Sixty right-handed, female adolescents (14-18 years) participated. 20 had a DSM-IV diagnosis of BPD, 20 had a different DSM-IV defined psychiatric disorder, and 20 were healthy controls. All groups were matched for age and IQ. Images were analysed using voxel-based morphometry.
No differences were found in limbic or white matter structures. Compared to healthy controls, adolescents with BPD displayed reduced gray matter in dorsolateral prefrontal cortex bilaterally and in left orbitofrontal cortex, but there were no significant differences in gray matter between BPD and other psychiatric patients. Like BPD patients, non-BPD psychiatric patients displayed significantly less gray matter in right dorsolateral prefrontal cortex compared to healthy controls.
These findings indicate that the prefrontal cortex is the earliest affected in the progression of BPD, but this does not distinguish it clearly from other psychiatric disorders. Alterations in limbic areas and white matter structures were not observed, but may play a later role in the progression of the illness.
Studies of schizophrenia with functional MRI showed hyper- and hypoactivations in various brain regions including the prefrontal cortex. Functional abnormalities have also been reported in first-degree relatives of schizophrenic patients. The aim of this study was to examine working memory related brain functions in healthy subjects, schizophrenic patients and unaffected relatives and to determine the influence of psychopathology on these processes.
A parametric n-back working memory task and functional MRI were used to examine 61 schizophrenic patients on antipsychotic medication, 11 nonpsychotic relatives of schizophrenic patients and a comparison group of 61 healthy subjects. The task difficulty was incrementally increased using a parametric task (0-back, 1-back, 2-back, and 3-back) to examine the relationship between working memory load, performance, and brain activity.
The results indicated that during the attention task (0-back) behavioral responses of patients and healthy subjects hardly differed but BOLD responses were considerably enhanced in schizophrenic patients. With increasing task difficulty differences between groups in BOLD responses diminished whereas behavioral deficits of patients increased. The examination of attention-independent working memory-functions (2- vs. 0-back) produced hypoactivations in patients, especially in frontal, temporal and subcortical brain regions. Behavioral performance and neural responses of unaffected relatives of schizophrenic patients were intermediate between schizophrenic patients and controls indicating slight brain dysfunctions. In addition, compensatory strategies were demonstrated.
These findings suggest that the genetic risk for schizophrenia is accompanied by neural inefficiency which is associated with cognitive deficits, especially in difficult tasks.
A diagnosis of dissociative identity disorder (DID) is controversial and prone to under- and misdiagnosis. From the moment of seeking treatment for symptoms to the time of an accurate diagnosis of DID individuals received an average of four prior other diagnoses and spent 7 years, with reports of up to 12 years, in mental health services.
To investigate whether data-driven pattern recognition methodologies applied to structural brain images can provide biomarkers to aid DID diagnosis.
Structural brain images of 75 participants were included: 32 female individuals with DID and 43 matched healthy controls. Individuals with DID were recruited from psychiatry and psychotherapy out-patient clinics. Probabilistic pattern classifiers were trained to discriminate cohorts based on measures of brain morphology.
The pattern classifiers were able to accurately discriminate between individuals with DID and healthy controls with high sensitivity (72%) and specificity (74%) on the basis of brain structure. These findings provide evidence for a biological basis for distinguishing between DID-affected and healthy individuals.
We propose a pattern of neuroimaging biomarkers that could be used to inform the identification of individuals with DID from healthy controls at the individual level. This is important and clinically relevant because the DID diagnosis is controversial and individuals with DID are often misdiagnosed. Ultimately, the application of pattern recognition methodologies could prevent unnecessary suffering of individuals with DID because of an earlier accurate diagnosis, which will facilitate faster and targeted interventions.
Declaration of interest
The authors declare no competing financial interests.
Highly detailed structural characterization is required to understand the discharge mechanism in order to effectively investigate α-MnO2 structured lithium battery cathode materials. This paper discusses recent findings which elucidate the lithiation mechanism of silver-hollandite, AgxMn8O16. For Ag1.2Mn8O16, the structure is not significantly perturbed during the first 2 equivalents of lithiation and the electrochemistry is highly reversible. Upon 4 equivalents of lithiation, the structure becomes highly distorted, in correlation with capacity fade observed over 40 cycles. Notably, regarding capacity fade, modifications to Ag/Mn ratio are less impactful than modifications to the α-MnO2 crystallite size. This is shown in comparisons of two materials with the same stoichiometry (Ag1.4Mn8O16) and differing crystallite size (10 and 15 nm).
Background: The Comprehensive Post-Acute Stroke Services (COMPASS) Study is one of the first large pragmatic randomized-controlled clinical trials using comparative effectiveness research methods, funded by the Patient-Centered Outcomes Research Institute. In the COMPASS Study, we compare the effectiveness of a patient-centered, transitional care intervention versus usual care for stroke patients discharged home from acute care. Outcomes include stroke patient post-discharge functional status and caregiver strain 90 days after discharge, and hospital readmissions. A central tenet of Patient-Centered Outcomes Research Institute-funded research is stakeholder engagement throughout the research process. However, evidence on how to successfully implement a pragmatic trial that changes systems of care in combination with robust stakeholder engagement is limited. This combination is not without challenges. Methods: We present our approach for broad-based stakeholder engagement in the context of a pragmatic trial with the participation of patients, caregivers, community stakeholders, including the North Carolina Stroke Care Collaborative hospital network, and policy makers. To maximize stakeholder engagement throughout the COMPASS Study, we employed a conceptual model with the following components: (1) Patient and Other Stakeholder Identification and Selection; (2) Patient and Other Stakeholder Involvement Across the Spectrum of Research Activities; (3) Dedicated Resources for Patient and Other Stakeholder Involvement; (4) Support for Patient and Other Stakeholder Engagement Through Organizational Processes; (5) Communication with Patients and Other Stakeholders; (6) Transparent Involvement Processes; (7) Tracking of Engagement; and (8) Evaluation of Engagement. Conclusion: In this paper, we describe how each component of the model is being implemented and how this approach addresses existing gaps in the literature on strategies for engaging stakeholders in meaningful and useful ways when conducting pragmatic trials.
Feather pecking is a serious economic and welfare problem in laying hens. Feather damage occurs mainly through severe feather pecking (SFP). Selection experiments have proved that this behavior is heritable and lines have been divergently selected for high (HFP) and low feather pecking (LFP). The number of bouts of SFP per hen follows a Poisson distribution with a maximum nearby 0. A few studies indicate that the distribution within flocks is not homogenous but contains sub-groups of birds showing extremely high levels of feather pecking (EFP). It was the aim of the current study to re-analyze data on SFP of lines selected for HFP/LFP and their F2 cross so as to uncover hidden sub-populations of EFP birds. Data of seven selection generations of HFP and LFP selection lines as well as their F2 cross have been used. We fitted a two-component mixture of Poisson distributions in order to separate the sub-group of EFP from the remaining birds. HFP and LFP lines differed mainly in mean bouts per bird. The proportion of EFP was only marginal in the LFP as compared with the HFP and the F2 population. Selection for LFP did not result in total elimination of EFP. The presence of even small proportions of EFP may play an important role in initiating outbreaks of feather pecking in large flocks. Further studies on feather pecking should pay special attention to the occurrence of EFP sub-groups.
Obsessive compulsive disorder (OCD) and social anxiety disorder (SAD) are characterized by biased perception and processing of potentially threatening stimuli. A hyper-reactivity of the fear-circuit [e.g. amygdala, anterior cingulate (ACC)] has been consistently reported using functional magnetic resonance imaging (fMRI) in SAD in comparison with healthy controls (HCs). Studies investigating the processing of specific emotional stimuli in OCD reported mainly orbitofrontal-striatal abnormalities. The goal of this study was to examine similar/common and differential neurobiological responses in OCD and SAD using unspecific emotional stimuli.
Fifty-four subjects participated: two groups (each n = 18) of outpatients with a current diagnosis of OCD or SAD, and 18 HCs. All subjects underwent fMRI while anticipating and perceiving unspecific visual stimuli with prior announced emotional valence (e.g. positive).
Compared to HCs, the combined patient group showed increased activation in amygdala, caudate and prefrontal/orbitofrontal cortex while anticipating unspecific emotional stimuli. Caudate was more active in the combined patient group during perception. A comparison between the OCD and the SAD samples revealed increased amygdala and decreased rostral ACC activation in OCD patients during perception, but no differences in the anticipation phase.
Overall, we could identify common fronto-subcortical hyper-reactivity in OCD and SAD while anticipating and perceiving unspecific emotional stimuli. While differential neurobiological responses between OCD and SAD when processing specific stimuli are evident from the literature, differences were less pronounced using unspecific stimuli. This could indicate a disturbance of emotion regulation common to both OCD and SAD.
Ca/vitamin D supplementation maintains bone health and decreases stress fracture risk during initial military training (IMT); however, there is evidence that Ca may negatively affect the absorption of other critical micronutrients, particularly Fe. The objective of this randomised, double-blind, placebo-controlled trial was to determine whether providing 2000 mg/d Ca and 25µg/d vitamin D in a fortified food product during 9 weeks of military training affects Fe status in young adults. Male (n 98) and female (n 54) volunteers enrolled in US Army basic combat training (BCT) were randomised to receive a snack bar with Ca/vitamin D (n 75) or placebo (snack bar without Ca/vitamin D; n 77) and were instructed to consume 2 snack bars/d between meals throughout the training course. Circulating ionised Ca was higher (P<0·05) following BCT among those consuming the Ca/vitamin D bars compared with placebo. Fe status declined in both groups over the course of BCT. Transferrin saturation, serum ferritin and Hb were reduced (P<0·05) and soluble transferrin receptor increased (P<0·05) following BCT. There were no differences (P>0·05) in markers of Fe status between placebo and Ca/vitamin D groups. Collectively, these data indicate that Ca/vitamin D supplementation through the use of a fortified food product consumed between meals does not affect Fe status during IMT.
In cats, the incidence of obesity and diabetes is increasing, and little is known about specific aspects of the endocrine control of food intake in this species. Recent data suggest that ghrelin has an important role in the control of insulin secretion and vice versa, but this role has never been demonstrated in cats. Here we aimed to improve our understanding about the relationship between insulin, amylin and ghrelin secretion in response to a nutrient load in overweight cats. After a 16 h fast, weekly, six overweight male cats underwent randomly one of the four testing sessions: saline, glucose, arginine and TAG. All solutions were isoenergetic and isovolumic, and were injected intravenously as a bolus. Glucose, insulin, acylated ghrelin (AG), amylin and prolactin were assayed in plasma before and 10, 20, 40, 60, 80 and 100 min after the nutrient load. A linear mixed-effects model was used to assess the effect of bolus and time on the parameters. A parenteral bolus of glucose or arginine increased insulin and ghrelin concentrations in cats. Except for with the TAG bolus, no suppression of ghrelin was observed. The absence of AG suppression after the intravenous load of arginine and glucose may suggest: (1) that some nutrients do not promote satiation in overweight cats; or that (2) AG may be involved in non-homeostatic consumption mechanisms. However, the role of ghrelin in food reward remains to be assessed in cats.
Accumulation is a key parameter governing the mass balance of the Greenland ice sheet. Several studies have documented the spatial variability of accumulation over wide spatial scales, primarily using point data, remote sensing or modeling. Direct measurements of spatially extensive, detailed profiles of accumulation in Greenland, however, are rare. We used 400 MHz ground-penetrating radar along the 1009 km route of the Greenland Inland Traverse from Thule to Summit during April and May of 2011, to image continuous internal reflecting horizons. We dated these horizons using ice-core chemistry at each end of the traverse. Using density profiles measured along the traverse, we determined the depth to the horizons and the corresponding water-equivalent accumulation rates. The measured accumulation rates vary from ~0.1 m w.e. a–1 in the interior to ~0.7 m w.e. a–1 near the coast, and correspond broadly with existing published model results, though there are some excursions. Comparison of our recent accumulation rates with those collected along a similar route in the 1950s shows a ~10% increase in accumulation rates over the past 52 years along most of the traverse route. This implies that the increased water vapor capacity of warmer air is increasing accumulation in the interior of Greenland.
Airbus and Boeing are cooperatively presenting this topic dealing with transport aircraft stalls. The paper will begin by defining a stall, followed by a review of requirements, predictive validation and flight testing. There are various ways of designing modern jet transports for the stall regime such as aerodynamic approaches, flight deck indications, and augmentation control laws to deal with the high angle-of-attack (α) arena. The goal of augmented control laws for high α is common – no full aerodynamic stall or loss of climb performance should occur in the operational flight envelope, in Normal flight control modes. The validation techniques employed in preparation for a flight test campaign will follow. These include flight characteristic predictions based on wind-tunnel data as well as pilot-in-the-loop simulation rehearsals. The preparation for flight testing will be reviewed from both the engineer and pilot viewpoints. This will be followed by a review of various flight testing that has been conducted. The paper will close with a brief foray into what the future of transport stalls could be – perhaps protection features in degraded flight control modes? What are the benefits as well as drawbacks to increased augmentation for high α?