Modification of the lithospheric stress field by lateral variations in plate-mantle coupling

[1] The presence of deeply penetrating continental roots may locally increase the magnitude of basal shear tractions by up to a factor of 4 compared to a layered viscosity structure. Here we examine how these increases in mantlelithosphere coupling influence stress patterns in the overlying elastic lithosphere. By coupling a mantle flow model to a model for the elastic lithosphere, we show that the amplification of mantle tractions beneath cratons increases elastic stress magnitudes by at most a factor of only 1.5 in a pattern not correlated to local basal traction changes. This disconnect is explained by the transmission of elastic stresses across large distances, which makes them sensitive to regionally-averaged changes in basal tractions, but not local variations. Our results highlight the importance of regional variations in lithospheric strength, which could allow stress patterns to more closely match regional changes in basal shear. Citation: Naliboff, J. B., C. P. Conrad, and C. Lithgow-Bertelloni (2009), Modification of the lithospheric stress field by lateral variations in plate-mantle coupling, Geophys. Res. Lett., 36, L22307

Modification of the lithospheric stress field by lateral variations in plate‐mantle coupling

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95471/1/grl26475.pd

Protocol for a randomized controlled study of Iyengar yoga for youth with irritable bowel syndrome

<p>Abstract</p> <p>Introduction</p> <p>Irritable bowel syndrome affects as many as 14% of high school-aged students. Symptoms include discomfort in the abdomen, along with diarrhea and/or constipation and other gastroenterological symptoms that can significantly impact quality of life and daily functioning. Emotional stress appears to exacerbate irritable bowel syndrome symptoms suggesting that mind-body interventions reducing arousal may prove beneficial. For many sufferers, symptoms can be traced to childhood and adolescence, making the early manifestation of irritable bowel syndrome important to understand. The current study will focus on young people aged 14-26 years with irritable bowel syndrome. The study will test the potential benefits of Iyengar yoga on clinical symptoms, psychospiritual functioning and visceral sensitivity. Yoga is thought to bring physical, psychological and spiritual benefits to practitioners and has been associated with reduced stress and pain. Through its focus on restoration and use of props, Iyengar yoga is especially designed to decrease arousal and promote psychospiritual resources in physically compromised individuals. An extensive and standardized teacher-training program support Iyengar yoga's reliability and safety. It is hypothesized that yoga will be feasible with less than 20% attrition; and the yoga group will demonstrate significantly improved outcomes compared to controls, with physiological and psychospiritual mechanisms contributing to improvements.</p> <p>Methods/Design</p> <p>Sixty irritable bowel syndrome patients aged 14-26 will be randomly assigned to a standardized 6-week twice weekly Iyengar yoga group-based program or a wait-list usual care control group. The groups will be compared on the primary clinical outcomes of irritable bowel syndrome symptoms, quality of life and global improvement at post-treatment and 2-month follow-up. Secondary outcomes will include visceral pain sensitivity assessed with a standardized laboratory task (water load task), functional disability and psychospiritual variables including catastrophizing, self-efficacy, mood, acceptance and mindfulness. Mechanisms of action involved in the proposed beneficial effects of yoga upon clinical outcomes will be explored, and include the mediating effects of visceral sensitivity, increased psychospiritual resources, regulated autonomic nervous system responses and regulated hormonal stress response assessed via salivary cortisol.</p> <p>Trial registration</p> <p>ClinicalTrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT01107977">NCT01107977</a>.</p

Enhanced Auditory Brainstem Response and Parental Bonding Style in Children with Gastrointestinal Symptoms

The electrophysiological properties of the brain and influence of parental bonding in childhood irritable bowel syndrome (IBS) are unclear. We hypothesized that children with chronic gastrointestinal (GI) symptoms like IBS may show exaggerated brainstem auditory evoked potential (BAEP) responses and receive more inadequate parental bonding. = 0.024). Multiple regression analysis in females also supported these findings.It is suggested that children with chronic GI symptoms have exaggerated brainstem responses to environmental stimuli and inadequate parental behaviors aggravate these symptoms

Complex fault interaction controls continental rifting

Continental rifting and break up processes are poorly constrained in the early stages. Here, the authors using high-resolution numerical simulations to show how early formed faults in continental extension can then control subsequent structure evolution of rifts

Brain imaging approaches to the study of functional GI disorders: a Rome working team report.

Progresses in the understanding of human brain-gut interactions in health and disease have been limited by the lack of non-invasive techniques to study brain activity. The advent of neuroimaging techniques has made it possible not only to study the structure and function of the brain, but also to characterize signaling system underlying brain function. This article gives a brief overview of relevant functional neuroanatomy, and of the most commonly used brain imaging techniques. It summarizes published functional brain imaging studies using acute visceral stimulation of the oesophagus, stomach and colon in healthy control subjects and patients with functional GI disorders, and briefly discusses pertinent findings from these studies. The article concludes with a critical assessment of published studies, and with recommendations for improved study paradigms and analysis strategies

Increased attentional network functioning related to symptom severity measures in females with irritable bowel syndrome

BackgroundIncreased attention to gastrointestinal (GI) symptoms and disease-specific contexts may play an important role in the enhanced perception of visceral stimuli frequently reported in patients with irritable bowel syndrome (IBS). In this study, we test the hypothesis that altered attentional mechanisms underlie central pain amplification in IBS.MethodsTo evaluate brain networks that support alerting, orienting, and executive attention, we employed the attention network test (ANT), a modified flanker task which measures the efficiency of functioning of core attentional networks, during functional magnetic resonance imaging in 15 IBS patients (mean age&nbsp;=&nbsp;31 [11.96]) and 14 healthy controls (HCs; mean age&nbsp;=&nbsp;31 [10.91]).Key resultsPatients with IBS, compared to HCs, showed shorter reaction times during the alerting and orienting conditions which were associated with greater activation of anterior midcingulate and insular cortices, and decreased activity in the right inferior frontal junction and supplementary motor cortex. Patients also showed activation in the dorsal medial prefrontal cortex and concurrent thalamic deactivation during the executive control portion of the ANT relative to HCs, but no group difference in reaction times were found. The activity in brain regions showing group differences during the ANT were associated with measures of GI-specific anxiety, pain catastrophizing, and fear of uncertainty. In IBS, activity in the anterior midcingulate during alerting correlated with duration of GI-symptoms and overall symptom severity.Conclusions &amp; inferencesTogether, these results suggest that IBS patients have specific abnormalities in attentional network functioning and these deficits may underlie symptom-related anxiety, hypervigilance, and visceral hypersensitivity