329 research outputs found

    The Medical Segmentation Decathlon

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    International challenges have become the de facto standard for comparative assessment of image analysis algorithms. Although segmentation is the most widely investigated medical image processing task, the various challenges have been organized to focus only on specific clinical tasks. We organized the Medical Segmentation Decathlon (MSD)—a biomedical image analysis challenge, in which algorithms compete in a multitude of both tasks and modalities to investigate the hypothesis that a method capable of performing well on multiple tasks will generalize well to a previously unseen task and potentially outperform a custom-designed solution. MSD results confirmed this hypothesis, moreover, MSD winner continued generalizing well to a wide range of other clinical problems for the next two years. Three main conclusions can be drawn from this study: (1) state-of-the-art image segmentation algorithms generalize well when retrained on unseen tasks; (2) consistent algorithmic performance across multiple tasks is a strong surrogate of algorithmic generalizability; (3) the training of accurate AI segmentation models is now commoditized to scientists that are not versed in AI model training

    The Medical Segmentation Decathlon

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    International challenges have become the de facto standard for comparative assessment of image analysis algorithms given a specific task. Segmentation is so far the most widely investigated medical image processing task, but the various segmentation challenges have typically been organized in isolation, such that algorithm development was driven by the need to tackle a single specific clinical problem. We hypothesized that a method capable of performing well on multiple tasks will generalize well to a previously unseen task and potentially outperform a custom-designed solution. To investigate the hypothesis, we organized the Medical Segmentation Decathlon (MSD) - a biomedical image analysis challenge, in which algorithms compete in a multitude of both tasks and modalities. The underlying data set was designed to explore the axis of difficulties typically encountered when dealing with medical images, such as small data sets, unbalanced labels, multi-site data and small objects. The MSD challenge confirmed that algorithms with a consistent good performance on a set of tasks preserved their good average performance on a different set of previously unseen tasks. Moreover, by monitoring the MSD winner for two years, we found that this algorithm continued generalizing well to a wide range of other clinical problems, further confirming our hypothesis. Three main conclusions can be drawn from this study: (1) state-of-the-art image segmentation algorithms are mature, accurate, and generalize well when retrained on unseen tasks; (2) consistent algorithmic performance across multiple tasks is a strong surrogate of algorithmic generalizability; (3) the training of accurate AI segmentation models is now commoditized to non AI experts

    New Developments in Cholinergic Imaging in Alzheimer and Lewy Body Disorders

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    © 2020, This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply. Purpose of Review: This paper aims to review novel trends in cholinergic neuroimaging in Alzheimer and Lewy body parkinsonian disorders. Recent Findings: The spectrum of cholinergic imaging is expanding with the availability of spatially more precise radioligands that allow assessment of previously less recognized subcortical and cortical structures with more dense cholinergic innervation. In addition, advances in MRI techniques now allow quantitative structural or functional assessment of both the cholinergic forebrain and the pedunculopontine nucleus, which may serve as non-invasive prognostic predictors. Multimodal imaging approaches, such as PET-MRI or multiligand PET, offer new insights into the dynamic and interactive roles of the cholinergic system at both local and larger-scale neural network levels. Summary: Our understanding of the heterogeneous roles of the cholinergic system in age-related diseases is evolving. Multimodal imaging approaches that provide complimentary views of the cholinergic system will be necessary to shed light on the impact of cholinergic degeneration on regional and large-scale neural networks that underpin clinical symptom manifestation in neurodegeneration

    Early intervention in psychosis

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    In the past 20 years, the evidence confirming the superiority of specialised early intervention services over generic care in managing the critical early phase of psychosis has grown steadily, and specialised early intervention services have been established in many parts of the developed world. The multidisciplinary, comprehensive and assertive approach of early intervention services was based on ground-breaking research showing the importance of minimising the duration of untreated psychosis, defining “at-risk” populations and optimising delivery of evidence-based treatment (psychotropic medication, other medication and non-pharmacological). Whilst studies have repeatedly shown positive short- and medium-term outcomes for early-intervention services, these appear to dissipate once care reverts to generic services. Early intervention in psychosis is now considered one of the most important mental health reforms since the era of deinstitutionalisation. Research efforts are now concentrating on understanding the pathophysiological processes that accompany the emergence and progression of psychosis, improving identification and treatment of at-risk mental states, developing focused early detection strategies and extending the early intervention paradigm to all youth mental health disorders

    Virtual Reality and Psychotic Disorders

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    In the early years of virtual reality in mental healthcare several reviews were published (Gregg and Tarrier 2007; G. Riva 2002; 2003; 2005). None of them mentions work done on virtual reality with psychotic disorders yet, though some early work was starting to get published around the same time. There are different psychotic disorders with each their own specified combination of symptom domains, symptom intensity and duration. Wood et al. (2011) suggest a dimensional staging of psychosis, ranging from psychotic-like experiences to severe persistent psychotic episodes. A large body of research is accumulating showing psychotic symptoms can be seen as a transdiagnostic and extended phenotype found in the general population (J. van Os and Reininghaus 2016). When psychotic experiences persist, transition to a psychotic disorder becomes a possibility. The main recognizable symptom domains of psychotic disorders are hallucinations and delusions. Hallucinations are perceptions a person experiences without a corresponding external stimulus. Hallucinations can occur for all five senses. Patients with a psychotic disorder for example often experience auditory hallucinations such as hearing voices. These voices can be commentary, give orders to the patient or call them names. Delusions are beliefs people have about the external reality which are strongly maintained despite strong evidence to the contrary or despite what almost everybody else (of a person’s culture or subculture) believes. The most common delusion found in psychotic disorders is the persecutory delusion (paranoia). People with a persecutory delusion feel others (known or unknown) spy on them, pursue them and threaten their safety (van der Gaag et al. 2012; Beck et al. 2009). Hallucinations and delusions often cause anxiety and make the patient avoid (social) situations, which can be treated with exposure therapy. Other symptom domains of psychotic disorders are negative symptoms and impaired cognition. Patients with negative symptoms experience an diminished emotional expression and avolition. Impaired cognition is about learning deficiencies, whether insufficiently thought or thwarted by deficits. For both negative symptoms and impaired cognition training can help patients learn to master new skills. There are some additional symptom domains in psychotic disorders, but these don’t play a part in virtual reality (yet). See Box 13.1 for an overview.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Interactive Intelligenc

    Ulk4 regulates GABAergic signaling and anxiety-related behavior

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    Excitation/inhibition imbalance has been proposed as a fundamental mechanism in the pathogenesis of neuropsychiatric and neurodevelopmental disorders, in which copy number variations of the Unc-51 like kinase 4 (ULK4) gene encoding a putative Serine/Threonine kinase have been reported in approximately 1/1000 of patients suffering pleiotropic clinical conditions of schizophrenia, depression, autistic spectrum disorder (ASD), developmental delay, language delay, intellectual disability, or behavioral disorder. The current study characterized behavior of heterozygous Ulk4(+/tm1a) mice, demonstrating that Ulk4(+/tm1a) mice displayed no schizophrenia-like behavior in acoustic startle reactivity and prepulse inhibition tests or depressive-like behavior in the Porsolt swim or tail suspension tests. However, Ulk4(+/tm1a) mice exhibited an anxiety-like behavioral phenotype in several tests. Previously identified hypo-anxious (Atp1a2, Ptn, and Mdk) and hyper-anxious (Gria1, Syngap1, and Npy2r) genes were found to be dysregulated accordingly in Ulk4 mutants. Ulk4 was found to be expressed in GABAergic neurons and the Gad67âș interneurons were significantly reduced in the hippocampus and basolateral amygdala of Ulk4(+/tm1a) mice. Transcriptome analyses revealed a marked reduction of GABAergic neuronal subtypes, including Pvalb, Sst, Cck, Npy, and Nos3, as well as significant upregulation of GABA receptors, including Gabra1, Gabra3, Gabra4, Gabra5, and Gabrb3. This is the first evidence that Ulk4 plays a major role in regulating GABAergic signaling and anxiety-like behavior, which may have implications for the development of novel anxiolytic treatments

    Progression from selective to general involvement of hippocampal subfields in schizophrenia

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    Volume deficits of the hippocampus in schizophrenia have been consistently reported. However, the hippocampus is anatomically heterogeneous; it remains unclear whether certain portions of the hippocampus are affected more than others in schizophrenia. In this study, we aimed to determine whether volume deficits in schizophrenia are confined to specific subfields of the hippocampus and to measure the subfield volume trajectories over the course of the illness. MRI scans were obtained from Dataset 1: 155 patients with schizophrenia (mean duration of illness of 7 years) and 79 healthy controls, and Dataset 2: an independent cohort of 46 schizophrenia patients (mean duration of illness of 18 years) and 46 healthy controls. In addition, follow-up scans were collected for a subset of Dataset 1. A novel, automated method based on an atlas constructed from ultra-high resolution, post-mortem hippocampal tissue was used to label 7 hippocampal subfields. Significant cross-sectional volume deficits in the CA1, but not of the other subfields, were found in the schizophrenia patients of Dataset 1. However, diffuse cross-sectional volume deficits across all subfields were found in the more chronic and ill schizophrenia patients of Dataset 2. Consistent with this pattern, the longitudinal analysis of Dataset 1 revealed progressive illness-related volume loss (~ 2 to 6% per year) that extended beyond CA1 to all of the other subfields. This decline in volume correlated with symptomatic worsening. Overall, these findings provide converging evidence for early atrophy of CA1 in schizophrenia, with extension to other hippocampal subfields and accompanying clinical sequelae over time

    Pregnenolone blocks cannabinoid-induced acute psychotic-like states in mice

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    Cannabis-induced acute psychotic-like states (CIAPS) represent a growing health issue, but their underlying neurobiological mechanisms are poorly understood. The use of antipsychotics and benzodiazepines against CIAPS is limited by side effects and/or by their ability to tackle only certain aspects of psychosis. Thus, safer wide-spectrum treatments are currently needed. Although the blockade of cannabinoid type-1 receptor (CB1) had been suggested as a therapeutical means against CIAPS, the use of orthosteric CB1 receptor full antagonists is strongly limited by undesired side effects and low efficacy. The neurosteroid pregnenolone has been recently shown to act as a potent endogenous allosteric signal-specific inhibitor of CB1 receptors. Thus, we tested in mice the potential therapeutic use of pregnenolone against acute psychotic-like effects of ?(9)-tetrahydrocannabinol (THC), the main psychoactive component of cannabis. We found that pregnenolone blocks a wide spectrum of THC-induced endophenotypes typically associated with psychotic-like states, including impairments in cognitive functions, somatosensory gating and social interaction. In order to capture THC-induced positive psychotic-like symptoms (e.g. perceptual delusions), we adapted a behavioral paradigm based on associations between different sensory modalities and selective devaluation, allowing the measurement of mental sensory representations in mice. Acting at hippocampal CB1 receptors, THC impaired the correct processing of mental sensory representations (reality testing) in an antipsychotic- and pregnenolone-sensitive manner. Overall, this work reveals that signal-specific inhibitors mimicking pregnenolone effects can be considered as promising new therapeutic tools to treat CIAPS.Bordeaux Region Aquitaine Initiative for NeuroscienceDissection des mécanismes hypothalamiques impliqués dans la détection du statut nutritionnel et régulation de la prise alimentaire via les interactions entre mTORC1, les mélanocortines et les endocannabinoïdes.The NGF system and its interplay with endocannabinoid signalling, from peripheral sensory terminals to the brain: new targets for the development of next generation drugs for neuropathic painCannabinoid receptors CB1 in schizophrenia: role of brain mitochondrial activity and astroglial signallingNeurocircuitry of endocannabinoid regulation of food intakeDevelopment of pregnenolone derivatives as allosteric inhibitors of CB1 cannabinoid receptors for thetreatment of schizophrenia and psychotic syndrome

    Altering the course of schizophrenia: progress and perspectives

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