Publications by authors named "Klaas Stephan"

Anxiety is one of the most common and debilitating mental health disorders, and is related to changes in interoception (perception of bodily states). While anxiety is more prevalent in women than men, gender differences in interoception-anxiety associations are often overlooked. Here, we examined gender-specific relationships between anxiety and interoception in the breathing domain, utilising multicentre data pooled from four study sites (N = 175; 51% women).

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Allostatic self-efficacy (ASE) represents a computational theory of fatigue and depression. In brief, it postulates that (i) fatigue is a feeling state triggered by a metacognitive diagnosis of loss of control over bodily states (persistently elevated interoceptive surprise); and that (ii) generalization of low self-efficacy beliefs beyond bodily control induces depression. Here, we converted ASE theory into a structural causal model (SCM).

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Article Synopsis
  • The study looked at how stopping antidepressant medicine affects a part of the brain called the amygdala that reacts to sad or negative faces.
  • It aimed to find out if this change in brain activity is connected to people becoming depressed again after they stop taking their medication.
  • The research involved tracking 83 patients who had previously been treated for depression and monitored them for 6 months after they stopped their meds to see if they relapsed into depression.
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Introduction: Anxiety is one of the most prevalent mental health conditions worldwide, and psychotherapeutic techniques can be employed to help manage and mitigate symptoms. While the available therapies are numerous, key strategies often involve cognitive and/or embodiment techniques. Within body-centered methods, breathing-oriented approaches are particularly prevalent, using either attention towards or active control of breathing.

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OCD has been conceptualized as a disorder arising from dysfunctional beliefs, such as overestimating threats or pathological doubts. Yet, how these beliefs lead to compulsions and obsessions remains unclear. Here, we develop a computational model to examine the specific beliefs that trigger and sustain compulsive behavior in a simple symptom-provoking scenario.

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Background: One in 3 patients relapse after antidepressant discontinuation. Thus, the prevention of relapse after achieving remission is an important component in the long-term management of major depressive disorder. However, no clinical or other predictors are established.

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Introduction: Interoception, the perception of the internal state of the body, has been shown to be closely linked to emotions and mental health. Of particular interest are interoceptive learning processes that capture associations between environmental cues and body signals as a basis for making homeostatically relevant predictions about the future. One method of measuring respiratory interoceptive learning that has shown promising results is the Breathing Learning Task (BLT).

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While interoception is of major neuroscientific interest, its precise definition and delineation from exteroception continue to be debated. Here, we propose a functional distinction between interoception and exteroception based on computational concepts of sensor-effector loops. Under this view, the classification of sensory inputs as serving interoception or exteroception depends on the sensor-effector loop they feed into, for the control of either bodily (physiological and biochemical) or environmental states.

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Prior studies have found metacognitive biases are linked to a transdiagnostic dimension of anxious-depression, manifesting as reduced confidence in performance. However, previous work has been cross-sectional and so it is unclear if under-confidence is a trait-like marker of anxious-depression vulnerability, or if it resolves when anxious-depression improves. Data were collected as part of a large-scale transdiagnostic, four-week observational study of individuals initiating internet-based cognitive behavioural therapy (iCBT) or antidepressant medication.

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Numerous disorders are characterised by fatigue as a highly disabling symptom. Fatigue plays a particularly important clinical role in multiple sclerosis (MS) where it exerts a profound impact on quality of life. Recent concepts of fatigue grounded in computational theories of brain-body interactions emphasise the role of interoception and metacognition in the pathogenesis of fatigue.

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After a first episode of major depressive disorder (MDD), there is substantial risk for a long-term remitting-relapsing course. Prevention and early interventions are thus critically important. Various studies have examined the feasibility of detecting at-risk individuals based on out-of-sample predictions about the future occurrence of depression.

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Article Synopsis
  • The study aimed to evaluate the effectiveness and acceptance of Standardized Patients (SPs) for training undergrad medical students in conducting psychiatric assessments and improving their communication skills.
  • The 3rd-year medical students, who had no clinical experience, learned through lectures and hands-on practice with SPs, followed by discussions with peers and faculty to reinforce their learning.
  • Survey results revealed that students felt they gained valuable skills in psychiatric interviewing and communication, finding the SPs authentic and the process enjoyable, suggesting this approach is beneficial for teaching psychiatry early in medical education.
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Background: Evidence-based treatments for depression exist but not all patients benefit from them. Efforts to develop predictive models that can assist clinicians in allocating treatments are ongoing, but there are major issues with acquiring the volume and breadth of data needed to train these models. We examined the feasibility, tolerability, patient characteristics, and data quality of a novel protocol for internet-based treatment research in psychiatry that may help advance this field.

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The risk of relapse after antidepressant medication (ADM) discontinuation is high. Predictors of relapse could guide clinical decision-making, but are yet to be established. We assessed demographic and clinical variables in a longitudinal observational study before antidepressant discontinuation.

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The auditory mismatch negativity (MMN) has been proposed as a biomarker of NMDA receptor (NMDAR) dysfunction in schizophrenia. Such dysfunction may be caused by aberrant interactions of different neuromodulators with NMDARs, which could explain clinical heterogeneity among patients. In two studies (N = 81 each), we used a double-blind placebo-controlled between-subject design to systematically test whether auditory mismatch responses under varying levels of environmental stability are sensitive to diminishing and enhancing cholinergic vs.

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Article Synopsis
  • * The dataset includes magnetic field dynamics, raw MRI data for one subject, and reconstructed images which will help assess correction methods and alternative reconstruction approaches for spiral fMRI.
  • * All collected data is stored in standardized formats, with raw data in ISMRMRD (HDF5) and imaging data in NIfTI, facilitating easy access and reproducibility for further research.
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Regression dynamic causal modeling (rDCM) is a novel and computationally highly efficient method for inferring effective connectivity at the whole-brain level. While face and construct validity of rDCM have already been demonstrated, here we assessed its test-retest reliability-a test-theoretical property of particular importance for clinical applications-together with group-level consistency of connection-specific estimates and consistency of whole-brain connectivity patterns over sessions. Using the Human Connectome Project dataset for eight different paradigms (tasks and rest) and two different parcellation schemes, we found that rDCM provided highly consistent connectivity estimates at the group level across sessions.

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Unlabelled: In generative modeling of neuroimaging data, such as dynamic causal modeling (DCM), one typically considers several alternative models, either to determine the most plausible explanation for observed data (Bayesian model selection) or to account for model uncertainty (Bayesian model averaging). Both procedures rest on estimates of the model evidence, a principled trade-off between model accuracy and complexity. In the context of DCM, the log evidence is usually approximated using variational Bayes.

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The basal ganglia (BG) are a group of subcortical nuclei responsible for motor and executive function. Central to BG function are striatal cells expressing D1 (D1R) and D2 (D2R) dopamine receptors. D1R and D2R cells are considered functional antagonists that facilitate voluntary movements and inhibit competing motor patterns, respectively.

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Article Synopsis
  • - Spiral fMRI is an alternative to traditional echo-planar imaging, offering faster acquisition speeds and higher efficiency, making it suitable for applications that need detailed imaging like laminar fMRI.
  • - However, spiral fMRI faces challenges like blurring artifacts due to magnetic field imperfections; recent advancements in signal modeling and iterative reconstruction have addressed these issues.
  • - The study demonstrates the effectiveness of high-resolution spiral fMRI at 7 Tesla, achieving excellent image quality and activation maps, and showcases its versatility with combined readouts to enhance sensitivity further.
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Dynamic Causal Modeling (DCM) is a Bayesian framework for inferring on hidden (latent) neuronal states, based on measurements of brain activity. Since its introduction in 2003 for functional magnetic resonance imaging data, DCM has been extended to electrophysiological data, and several variants have been developed. Their biophysically motivated formulations make these models promising candidates for providing a mechanistic understanding of human brain dynamics, both in health and disease.

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Interoception, the perception of internal bodily states, is thought to be inextricably linked to affective qualities such as anxiety. Although interoception spans sensory to metacognitive processing, it is not clear whether anxiety is differentially related to these processing levels. Here we investigated this question in the domain of breathing, using computational modeling and high-field (7 T) fMRI to assess brain activity relating to dynamic changes in inspiratory resistance of varying predictability.

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Interoception and homeostatic/allostatic control are intertwined branches of closed-loop brain-body interactions (BBI). Given their importance in mental and psychosomatic disorders, establishing computational assays of BBI represents a clinically important but methodologically challenging endeavor. This technical note presents a novel approach, derived from a generic computational model of homeostatic/allostatic control that underpins (meta)cognitive theories of affective and psychosomatic disorders.

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Dynamic causal models (DCMs) of electrophysiological data allow, in principle, for inference on hidden, bulk synaptic function in neural circuits. The directed influences between the neuronal elements of modeled circuits are subject to delays due to the finite transmission speed of axonal connections. Ordinary differential equations are therefore not adequate to capture the ensuing circuit dynamics, and delay differential equations (DDEs) are required instead.

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