866 research outputs found

    Importance of GNSS data quality assessment with novel control criteria in professional soccer match- play

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    This is an Accepted Manuscript of an article published by Taylor & Francis in International Journal of Performance Analysis in Sport on 06/07/2021, available online: https://doi.org/10.1080/24748668.2021.1947017This study assessed the quality of Global Navigation Satellite System (GNSS) signal during professional football match-play in different stadia with the application of a novel Data Quality Control Criteria (DQCC). DQCC was applied to GPS-files from match-play, derived using 10 Hz GNSS devices for 27 professional soccer players across a season to assess external load measures accounting for poor positioning quality (%) and horizontal dilution of precision. Performances were categorised on playing position as Wide or Central to assess proximity to stand cover on GNSS signal quality. An average reduction in total distance (11.2%), high-speed running distance (6.4%), sprint distance (7.0%), accelerations (10.3%) and decelerations (10.0%) (all P <0.01) was observed upon DQCC application. In worst cases, 90% of an external variable was affected by poor quality signal. Signal quality was worse for wide positioned players than centrally positioned (positioning quality 2.6% lower (P <0.01)), resulting in a larger reduction of external variables upon DQCC application. Large stands in football stadia affect the data quality of GNSS and is exacerbated for players positioned closer to stand cover. Viewing only data with acceptable Position Quality and HDOP meaningfully reduces measured external loads, which has implications for the application of match data

    Highlights of this issue

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    Outcomes in treatment-resistant schizophrenia: symptoms, function and clozapine plasma concentrations

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    Background: Clozapine is the only medication licenced for treating patients with treatment-refractory schizophrenia. However, there are no evidence-based guidelines as to the optimal plasma level of clozapine to aim for, and their association with clinical and functional outcome. Objective: We assessed the relationship between clinical and functional outcome measures and blood concentrations of clozapine among patients with treatment-refractory psychosis. Methods: Data were reviewed in 82 patients with treatment-refractory psychosis admitted to a specialised tertiary-level service and treated with clozapine. Analysis focussed on the relationship between clozapine and norclozapine plasma concentrations and the patientā€™s clinical symptoms and functional status. Results: Clinical symptom improvement was positively correlated with norclozapine plasma concentrations and inversely correlated with clozapine to norclozapine plasma concentrations ratio. Clozapine concentrations showed a bimodal association with clinical improvement (peaks around 350 and 660ā€‰ng/ml). Clinical symptom improvement correlated with functional outcomes, although there was no significant correlation between the latter and clozapine or norclozapine plasma concentrations. Conclusion: Clozapine treatment was associated with optimal clinical improvement at two different peak plasma concentrations around 350 and 650ā€‰ng/ml. Clinical improvement was associated with functional outcome; however, functionality was not directly associated with clozapine concentrations. A subset of patients may require higher clozapine plasma concentrations to achieve clinical improvement

    The influence of trial-by-trial feedback on trust in health, first-episode and chronic psychosis

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    Trust is crucial to establishing reciprocal, positive social interactions and seems to be compromised in psychosis. The trust game offers methods to assess an individualā€™s trust responses to trust-reciprocating, positive feedback. Various computational techniques have been implemented to measure trust responsiveness, mostly based on investments. Here, we propose a new method, focusing on feedback response. Psychosis patients show social dysfunction and reduced trust during early and more progressed illness stages. The present study inspects differences in feedback responsiveness of 102 first-episode psychosis patients (FEPs), 43 chronic psychosis patients (CPs), and 39 healthy controls (HCs) by adopting a novel assessment approach. Additionally, baseline trust, the trust exerted without any prior knowledge of the partnerā€™s trustworthiness, and mean trust were examined. Participants performed a multi-round trust game, playing the investor role, and were paired with a computer, programmed to return at least the invested amount, representing a trustworthy partner. The new method detected group differences, more distinguished than the former methods. Contrary to our expectations, baseline trust was intact in patients. Relative to HCs, patients were less responsive to feedback, failing to integrate the positive information into their decision-making process. The magnitude of returns was not associated with increases in trust. This novel method showed promising results and confirmed patientsā€™ deficits within the social interactional domain

    The importance of pro-social processing, and ameliorating dysfunction in schizophrenia. An FMRI study of oxytocin

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    Schizophrenia is often a severe and debilitating mental illness, frequently associated with impairments in social cognition that hinder individuals' abilities to relate to others and integrate effectively in society. Oxytocin has emerged as a putative therapeutic agent for treating social deficits in schizophrenia, but the mode of action remains unclear. This placebo-controlled crossover study aimed to elucidate the neural underpinnings of oxytocin administration in patients with schizophrenia. 20 patients with schizophrenia were examined using functional magnetic resonance imaging under oxytocin (40 IU) or placebo nasal spray. Participants performed a stochastically rewarded decision-making task that incorporated elements of social valence provided by different facial expressions, i.e. happy, angry and neutral. Oxytocin attenuated the normal bias in selecting the happy face accompanied by reduced activation in a network of brain regions that support mentalising, processing of facial emotion, salience, aversion, uncertainty and ambiguity in social stimuli, including amygdala, temporo-parietal junction, posterior cingulate cortex, precuneus and insula. These pro-social effects may contribute to the facilitation of social engagement and social interactions in patients with schizophrenia and warrant further investigation in future clinical trials for social cognitive impairments in schizophrenia

    Contextual perception under active inference

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    Human social interactions depend on the ability to resolve uncertainty about the mental states of others. The context in which social interactions take place is crucial for mental state attribution as sensory inputs may be perceived differently depending on the context. In this paper, we introduce a mental state attribution task where a target-face with either an ambiguous or an unambiguous emotion is embedded in different social contexts. The social context is determined by the emotions conveyed by other faces in the scene. This task involves mental state attribution to a target-face (either happy or sad) depending on the social context. Using active inference models, we provide a proof of concept that an agentā€™s perception of sensory stimuli may be altered by social context. We show with simulations that context congruency and facial expression coherency improve behavioural performance in terms of decision times. Furthermore, we show through simulations that the abnormal viewing strategies employed by patients with schizophrenia may be due to (i) an imbalance between the precisions of local and global features in the scene and (ii) a failure to modulate the sensory precision to contextualise emotions

    Two Eyes for an Eye: The Neuroscience of Force Escalation

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    A systematic review of TMS and neurophysiological biometrics in patients with schizophrenia

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    Transcranial magnetic stimulation can be combined with electromyography (TMS-EMG) and electroencephalography (TMS-EEG) to evaluate the excitatory and inhibitory functions of the cerebral cortex in a standardized manner. It has been postulated that schizophrenia is a disorder of functional neural connectivity underpinned by a relative imbalance of excitation and inhibition. The aim of this review was to provide a comprehensive overview of TMS-EMG and TMS-EEG research in schizophrenia, focused on excitation or inhibition, connectivity, motor cortical plasticity and the effect of antipsychotic medications, symptom severity and illness duration on TMS-EMG and TMS-EEG indices. We searched PsycINFO, Embase and Medline, from database inception to April 2020, for studies that included TMS outcomes in patients with schizophrenia. We used the following combination of search terms: transcranial magnetic stimulation OR tms AND interneurons OR glutamic acid OR gamma aminobutyric acid OR neural inhibition OR pyramidal neurons OR excita* OR inhibit* OR GABA* OR glutam* OR E-I balance OR excitation-inhibition balance AND schizoaffective disorder* OR Schizophrenia OR schizophreni*. TMS-EMG and TMS-EEG measurements revealed deficits in excitation or inhibition, functional connectivity and motor cortical plasticity in patients with schizophrenia. Increased duration of the cortical silent period (a TMS-EMG marker of Ī³-aminobutyric acid B receptor activity) with clozapine was a relatively consistent finding. Most of the studies used patients with chronic schizophrenia and medicated patients, employed cross-sectional group comparisons and had small sample sizes. TMS-EMG and TMS-EEG offer an opportunity to develop a novel and improved understanding of the physiologic processes that underlie schizophrenia and to assess the therapeutic effect of antipsychotic medications. In the future, these techniques may also help predict disease progression and further our understanding of the excitatory/inhibitory balance and its implications for mechanisms that underlie treatment-resistant schizophrenia. [Abstract copyright: Ā© 2021 CMA Joule Inc. or its licensors.
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