Using Virtual Reality to Study Spatial Mapping and Threat Learning

Using spatial mapping processes to learn about threat and safety in an environment is crucial for survival. Research using conditioning paradigms has explored the effects of state (transient arousal) and trait anxiety (anxiety as an aspect of personality) on threat learning and acquisition. However, results are mixed, and little is known regarding why some individuals do not learn to discriminate between threat and safety during contextual conditioning. We used a virtual reality (VR) contextual threat conditioning paradigm to elucidate the effects of state and trait anxiety on contextual threat learning. 70 healthy participants (46 female) navigated and "picked" flowers in a VR environment. Flowers picked in the dangerous zone (half of the environment) were paired with an electric shock (or "bee sting") to the hand; flowers picked in the safe zone were never paired with a shock. Participants also collected and returned neutral objects as a measure of spatial memory. Galvanic skin response (GSR) was measured throughout the task and anxiety was assessed via the State Trait Anxiety Inventory (STAI). Participants were categorized as learners if they correctly identified the two zones after the task. Non-learners, compared to learners, performed significantly worse during the spatial memory task and demonstrated significantly higher state anxiety scores and GSR levels throughout the task. Learners showed higher skin conductance response (SCR) in the dangerous zone compared to the safe zone while non-learners showed no SCR differences between zones. These results indicate that state anxiety may impair spatial mapping, disrupting contextual threat learning.

Intrusive Traumatic Re-Experiencing Domain: Functional Connectivity Feature Classification by the ENIGMA PTSD Consortium

Background

Intrusive traumatic re-experiencing domain (ITRED) was recently introduced as a novel perspective on posttraumatic psychopathology, proposing to focus research of posttraumatic stress disorder (PTSD) on the unique symptoms of intrusive and involuntary re-experiencing of the trauma, namely, intrusive memories, nightmares, and flashbacks. The aim of the present study was to explore ITRED from a neural network connectivity perspective.

Methods

Data were collected from 9 sites taking part in the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) PTSD Consortium (n= 584) and included itemized PTSD symptom scores and resting-state functional connectivity (rsFC) data. We assessed the utility of rsFC in classifying PTSD, ITRED-only (no PTSD diagnosis), and trauma-exposed (TE)-only (no PTSD or ITRED) groups using a machine learning approach, examining well-known networks implicated in PTSD. A random forest classification model was built on a training set using cross-validation, and the averaged cross-validation model performance for classification was evaluated using the area under the curve. The model was tested using a fully independent portion of the data (test dataset), and the test area under the curve was evaluated.

Results

rsFC signatures differentiated TE-only participants from PTSD and ITRED-only participants at about 60% accuracy. Conversely, rsFC signatures did not differentiate PTSD from ITRED-only individuals (45% accuracy). Common features differentiating TE-only participants from PTSD and ITRED-only participants mainly involved default mode network-related pathways. Some unique features, such as connectivity within the frontoparietal network, differentiated TE-only participants from one group (PTSD or ITRED-only) but to a lesser extent from the other group.

Conclusions

Neural network connectivity supports ITRED as a novel neurobiologically based approach to classifying posttrauma psychopathology.

Persistence of Müllerian derivatives and intestinal lymphangiectasis in two newborn brothers: confirmation of the Urioste syndrome

We describe two newborn brothers with a pattern of malformation characterized by the persistence of Müllerian duct derivatives, intestinal lymphangiectasia, hypertrophied alveolar ridges, and early death. Postmortem examination showed the presence of a rudimentary uterus, fallopian tubes, the upper third of a vagina, a prostate of normal shape, a dilated colon, and generalized intestinal and pulmonary lymphangiectasia. The syndrome was first delineated by Urioste and co-workers [1993: Am J Med Genet 47:494-503]. These cases confirm the existence of a definite and distinct entity.

The spleen in the Wiskott-Aldrich syndrome: histopathologic abnormalities of the white pulp correlate with the clinical phenotype of the disease

The Wiskott-Aldrich syndrome (WAS) is a X-linked hematologic disorder characterized by thrombocytopenia, eczema, and immunodeficiency of variable severity. Reported here are the results of a morphologic, morphometric, and immunophenotypic analysis of splenic lymphoid tissue in 12 WAS patients with documented molecular defect and with different disease severity. Spleens from 29 age-matched patients with different diseases were used as controls. Paraffin-embedded tissue (from all cases) and fresh-frozen samples (from 5 WAS patients and 4 control subjects) were used to study the different white pulp compartments by classic morphologic, immunophenotyping, and image analysis techniques. Data were statistically analyzed by both parametric and nonparametric tests. Spleens from WAS patients showed a significant depletion of the total white pulp (p = 0.0008), T cell (p < 0.05), and B cell (p = 0.0002) areas and marginal zone (MZ) thickness (p < 0.0001). Among WAS patients, a negative correlation was found between the score of severity of the disease and all variables considered (Spearman's rank correlation coefficient, r = -0.79, r = -0.73, r = -0.68, and r = -0.56, respectively). In conclusion, this study shows that in WAS a general depletion of the splenic white pulp occurs, supporting the evidence that WAS is characterized by a combined immune defect. The significant reduction of the MZ may explain the inability of WAS patients to mount a response to T-independent antigens.

Chronic hepatitis C in children: the pathological and clinical spectrum

BACKGROUND & AIMS

Apart from the high-risk groups, the pathology of chronic hepatitis C in children is not well known. The aim of this study was to investigate the morphology of chronic hepatitis C in children without any underlying systemic disease and to evaluate its relationship to clinicovirological factors.

METHODS

Liver biopsy specimens from 80 children positive for antibody to hepatitis C virus were evaluated using a semiquantitative scoring system.

RESULTS

Chronic hepatitis was mild in most cases but had high-grade activity in 17 children (21.2%). A significant association was found between the grade of focal necrosis and alanine transaminase levels (P < 0.003). Fibrosis was absent in 22 cases (27.5%), mild in 44 (55%), and moderate in 13 (16.2%). Only 1 patient had cirrhosis. A significant relationship was detected between fibrosis scores and (1) duration of disease (P < 0.03); (2) portal inflammation (P < 0. 002); and (3) interface hepatitis (P < 0.003).

CONCLUSIONS

In otherwise healthy children, chronic hepatitis C is a morphologically mild disease in most cases. Fibrosis increases with the duration of disease, suggesting that end-stage disease may develop in young adulthood. Alanine transaminase levels correlate with intralobular focal necrosis but not with other lesions. In this respect, liver biopsy retains its importance in the management of chronic hepatitis C in children.

Yellow nail syndrome and bilateral cystic lung disease

In patients with yellow nail syndrome (YNS), highly characteristic nail changes are often associated with lymphedema and respiratory disorders due to pleural effusions or bronchiectasis. We describe a 4-year-old girl with the YNS who also had cystic lesions of the lung, affecting first the left lower lobe and, after surgical resection of the involved segments, also the right lower lobe. We discuss the etiology of the pulmonary cysts and hypothesize that abnormalities in pulmonary lymphatic flow, characteristic of YNS, may have decreased lung tissue compliance and determined the unusual progression of the cystic lesions in this patient.