Crystallographic features of the approximant H (Mn7_7Si2_2V) phase in the Mn-Si-V alloy system

The intermetallic compound H (Mn$_7$Si$_2$V) phase in the Mn-Si-V alloy system can be regarded as an approximant phase of the dodecagonal quasicrystal as one of the two-dimensional quasicrystals. To understand the features of the approximant H phase, in this study, the crystallographic features of both the H phase and the (\sigma $\, \rightarrow$ H) reaction in Mn-Si-V alloy samples were investigated, mainly by transmission electron microscopy. It was found that, in the H phase, there were characteristic structural disorders with respect to an array of a dodecagonal structural unit consisting of 19 dodecagonal atomic columns. Concretely, penetrated structural units consisting of two dodecagonal structural units were presumed to be typical of such disorders. An interesting feature of the (\sigma $\, \rightarrow$ H) reaction was that regions with a rectangular arrangement of penetrated structural units (RAPU) first appeared in the \sigma $\,$ matrix as the initial state, and H regions were then nucleated in contact with RAPU regions. The subsequent conversion of RAPU regions into H regions eventually resulted in the formation of the approximant H state as the final state. Furthermore, atomic positions in both the H structure and the dodecagonal quasicrystal were examined using a simple plane-wave model with twelve plane waves.Comment: 29 pages, 12 figure

Neurovisceral phenotypes in the expression of psychiatric symptoms

This review explores the proposal that vulnerability to psychological symptoms, particularly anxiety, originates in constitutional differences in the control of bodily state, exemplified by a set of conditions that include Joint Hypermobility, Postural Tachycardia Syndrome and Vasovagal Syncope. Research is revealing how brainbody mechanisms underlie individual differences in psychophysiological reactivity that can be important for predicting, stratifying and treating individuals with anxiety disorders and related conditions. One common constitutional difference is Joint Hypermobility, in which there is an increased range of joint movement as a result of a variant of collagen. Joint hypermobility is over-represented in people with anxiety, mood and neurodevelopmental disorders. It is also linked to stress-sensitive medical conditions such as irritable bowel syndrome, chronic fatigue syndrome and fibromyalgia. Structural differences in 'emotional' brain regions are reported in hypermobile individuals, and many people with joint hypermobility manifest autonomic abnormalities, typically Postural Tachycardia Syndrome. Enhanced heart rate reactivity during postural change and as recently recognised factors causing vasodilatation (as noted post prandially, post exertion and with heat) is characteristic of Postural Tachycardia Syndrome, and there is a phenomenological overlap with anxiety disorders, which may be partially accounted for by exaggerated neural reactivity within ventromedial prefrontal cortex. People who experience Vasovagal Syncope, a heritable tendency to fainting induced by emotional challenges (and needle/blood phobia), are also more vulnerable to anxiety disorders. Neuroimaging implicates brainstem differences in vulnerability to faints, yet the structural integrity of the caudate nucleus appears important for the control of fainting frequency in relation to parasympathetic tone and anxiety. Together there is clinical and neuroanatomical evidence to show that common constitutional differences affecting autonomic responsivity are linked to psychiatric symptoms, notably anxiety

Neural correlates of outcome of the psychotherapy compared to antidepressant therapy in anxiety and depression disorders: a meta-analysis

The most prevalent mental disorders, anxiety and depression, are commonly associated with structural and functional changes in the fronto-limbic brain areas. The clinical trials investigating patients with affective disorders showed different outcome to different treatments such as psychotherapy or pharmacotherapy. It is, however, still unexplored how these interventions approach affect the functional brain. This meta-analysis aims to compare the effects of psychotherapy compared to antidepressant therapy on functional brain activity in anxiety and depression disorders. Twenty-one samples with psychotherapy and seventeen samples with antidepressant therapy were included. The main finding showed an inverse effect of the two treatments on the right paracingulate activity. The patients undergoing psychotherapy showed an increase in the right paracingulate activity while pharmacological treatment led to a decrease of activation of this area. This finding seems to support the recent studies that hypothesize how psychotherapy, through the self-knowledge and the meaning processing, involves a top-down emotional regulation

Neuroimaging in Functional Movement Disorders.

PURPOSE OF REVIEW: Functional movement disorders are common and disabling causes of abnormal movement control. Here, we review the current state of the evidence on the use of neuroimaging in Functional movement disorders, particularly its role in helping to unravel the pathophysiology of this enigmatic condition. RECENT FINDINGS: In recent years, there has been a shift in thinking about functional movement disorder, away from a focus on high-level psychological precipitants as in Freudian conversion theories, or even an implicit belief they are 'put-on' for secondary gain. New research has emphasised novel neurobiological models incorporating emotional processing, self-representation and agency. Neuroimaging has provided new insights into functional movement disorders, supporting emerging neurobiological theories implicating dysfunctional emotional processing, self-image and sense of agency. Recent studies have also found subtle structural brain changes in patients with functional disorders, arguing against a strict functional/structural dichotomy

Exploring face perception in disorders of development: evidence from Williams syndrome and autism

Individuals with Williams syndrome (WS) and autism are characterized by different social phenotypes but have been said to show similar atypicalities of face-processing style. Although the structural encoding of faces may be similarly atypical in these two developmental disorders, there are clear differences in overall face skills. The inclusion of both populations in the same study can address how the profile of face skills varies across disorders. The current paper explored the processing of identity, eye-gaze, lip-reading, and expressions of emotion using the same participants across face domains. The tasks had previously been used to make claims of a modular structure to face perception in typical development. Participants with WS (N=15) and autism (N=20) could be dissociated from each other, and from individuals with general developmental delay, in the domains of eye-gaze and expression processing. Individuals with WS were stronger at these skills than individuals with autism. Even if the structural encoding of faces appears similarly atypical in these groups, the overall profile of face skills, as well as the underlying architecture of face perception, varies greatly. The research provides insights into typical and atypical models of face perception in WS and autism

Predicting development of adolescent drinking behaviour from whole brain structure at 14 years of age

Adolescence is a common time for initiation of alcohol use and development of alcohol use disorders. The present study investigates neuroanatomical predictors for trajectories of future alcohol use based on a novel voxel-wise whole-brain structural equation modeling framework. In 1814 healthy adolescents of the IMAGEN sample, the Alcohol Use Disorder Identification Test (AUDIT) was acquired at three measurement occasions across five years. Based on a two-part latent growth curve model, we conducted whole-brain analyses on structural MRI data at age 14, predicting change in alcohol use score over time. Higher grey-matter volumes in the caudate nucleus and the left cerebellum at age 14 years were predictive of stronger increase in alcohol use score over 5 years. The study is the first to demonstrate the feasibility of running separate voxel-wise structural equation models thereby opening new avenues for data analysis in brain imaging

Imaging Studies of Aging, Neurodegenerative Disease, and Alcoholism.

Neurodegenerative diseases such as Alzheimers disease, disorders such as alcoholism, and the aging process can lead to impaired cognitive function and dementia. Researchers and clinicians have used noninvasive imaging techniques to determine the structural and physiological alterations in the brain that are associated with these conditions. Analyses of the brains structure have found that shrinkage (atrophy) of the brain tissue is characteristic for all conditions associated with dementia, but that the specific locations of atrophied brain structures vary among different neurodegenerative diseases and alcohol-induced disorders. Similarly, studies analyzing the metabolism in various brain structures have found that, depending on whether dementia was induced by neurodegenerative diseases, alcoholism, or aging, the affected brain structures vary slightly. Based on such studies, researchers and clinicians now can more accurately define different types of dementia and predict their clinical course