Neural network modelling of the influence of channelopathies on reflex visual attention

Research in computational neuroscience has the potential to bridge the gap between the neuroscientific descriptions of neural structures and dynamics, and the psychological models of behaviour and mental states. In particular, simulated neural network models with output or dynamics that are interpretable in terms of behaviour can help to understand neurodynamics and assess the plausibility of vertical theories of cognition. This thesis presents two contributions to the domain: EVAC, a model of emergent visual attention in presence of calcium channelopathy, and PyCogMo, a model learning framework. By modelling channelopathy, EVAC constitutes an effort towards identifying the possible causes of autism. The network structure embodies the dual pathways model of cortical processing of visual input, with reflex attention as an emergent property of neural interactions. EVAC extends a model developed by O'Reilly and Munakata [1] by introducing attention shift in a larger-scale network and applying a phenomenological model of channelopathy. The simulation of EVAC results in testable behavioural predictions on reflex attention shift tasks inspired by Posner [2]. In presence of a distractor, the channelopathic network's rate of failure to shift attention is lower than the control network's, but overall, the control network exhibits a lower classification error rate. The simulation results also show differences in task-relative reaction times between control and channelopathic networks. The attention shift timings inferred from the model are consistent with studies of attention shift in autistic children. Often, generative methods, like the simulation of the model of EVAC, require to train the synaptic weights using specialised neural networks learning algorithms. In the EVAC model, the weights are learnt with the Leabra algorithm \cite{cecn}. Emergent is the only neural simulator implementing the Leabra algorithm. Consequently, the EVAC network could not be developed in a simulator-independent manner that would allow it to be run on a variety of implementations to improve the reliability of the results. While PyNN [3] is a software framework that offers the possibility to specify and run a model on several otherwise incompatible simulators, training those networks remains a simulator-dependent task, for which PyNN is not suited. Hence, PyCogMo, a novel learning framework based on PyNN, was developed to address this limitation. It enables modellers to implement and use learning algorithms with several simulators. PyCogMo constitutes a step towards improving the reproducibility of computational experiments across simulators, hence a valuable methodological support for computational neuroscientists.DOCTOR OF PHILOSOPHY (SCE

A Bullet in the Supraspinatus Compartment Successfully Removed by Arthroscopy: Case Report and Review of the Literature

Arthroscopic removal of bullet from intra-articular compartment has been described for several joints. Only few reports dealing with this condition in the shoulder have been reported especially for the glenohumeral and the subacromial compartments. We report the story of a fifty-seven-year-old man presenting a bullet in the supraspinatus compartment of his left shoulder successfully removed by arthroscopy

Neural network modelling of the influence of channelopathies on reflex visual attention

This paper introduces a model of Emergent Visual Attention in presence of calcium channelopathy (EVAC). By modelling channelopathy, EVAC constitutes an effort towards identifying the possible causes of autism. The network structure embodies the dual pathways model of cortical processing of visual input, with reflex attention as an emergent property of neural interactions. EVAC extends existing work by introducing attention shift in a larger-scale network and applying a phenomenological model of channelopathy. In presence of a distractor, the channelopathic network’s rate of failure to shift attention is lower than the control network’s, but overall, the control network exhibits a lower classification error rate. The simulation results also show differences in task-relative reaction times between control and channelopathic networks. The attention shift timings inferred from the model are consistent with studies of attention shift in autistic children

Do double-row suture-locking anchors impact the biomechanical outcomes of rotator cuff surgery? A biomechanical study

International audienceIntroduction: Several surgical techniques for arthroscopic repair of the rotator cuff have been described in the literature. The aim of this study was to determine whether the suture thread locking method in double-row anchors influences their biomechanical properties. We compared the pullout strength of two anchors with different locking mechanisms.Introduction: Several surgical techniques for arthroscopic repair of the rotator cuff have been described in the literature. The aim of this study was to determine whether the suture thread locking method in double-row anchors influences their biomechanical properties. We compared the pullout strength of two anchors with different locking mechanisms.Methods: We performed 30 pullout tests at 135° using two different double-row anchors, an interference fit lock (5.5 mm SwiveLock) and a combination lock (5.5 mm MultiFix S). One anchor of each type was implanted on the tuberosity of a bovine humeral bone.Results: Mean pullout strength was 239.29 ± 83.73 N for the SwiveLock anchors and 253.82 ± 87.65 N for the MultiFIX S anchors, mean displacement (in millimeters) was 28 ± 9 and 30 ± 12, respectively which were not statistically significantly different.Conclusion: The addition of an internal lock in the double-row suture-locking anchor did not improve the biomechanical properties in a pullout test of 135

Total shoulder prosthesis with humeral resurfacing: Impact on lateral offset and short-term clinical consequences

International audienceBACKGROUND:Reports of early glenoid wear after humeral resurfacing hemiarthroplasty have prompted the use, in combination with this procedure, of newly developed glenoid implants. This combination can increase global humeral offset. The objectives of this study were to assess changes in overall lateral offset and their potential short-term clinical consequences after combined humeral resurfacing and glenoid replacement.HYPOTHESIS:Combined humeral resurfacing and glenoid replacement induces a large increase in overall lateral offset, resulting in short-term clinical consequences.MATERIAL AND METHODS:A single-centre prospective study was started in November 2011. Consecutive patients scheduled for total shoulder arthroplasty with humeral resurfacing were included. The primary outcome measure was the change in lateral offset between radiographs obtained pre-operatively and 3 months post-operatively. The functional outcome assessed using the Constant score was compared between the groups with a lateral offset change <10mm vs. ≥10mm.RESULTS:From November 2011 to November 2014, 35 total shoulder arthroplasties with humeral resurfacing were performed in 32 patients with a mean age of 72.1 years (range, 55-86 years). Mean follow-up was 20±6 months (range, 12-31 months). Overall lateral offset was significantly greater post-operatively than pre-operatively (14±6mm vs. 5±7mm, p<0.0001), the mean difference being 8mm (range, 2-20mm). Post-operative range of motion was better in the group with an overall lateral offset ≥10mm (p=0.0016).DISCUSSION:Combined humeral resurfacing and glenoid replacement markedly increases overall lateral offset. This increase is not associated with adverse effects on short-term function and may improve post-operative motion range. However, greater lateral offset elevates the loads on the glenoid implant, which may increase the risk of glenoid implant loosening and rotator cuff tearing. Close radiological monitoring is therefore imperative.LEVEL OF EVIDENCE:IV, prospective cohort study

Arthroscopy-assisted fixation of fracture of the distal part of the clavicle by subcoracoid suture and clavicle button.

Place: FranceINTRODUCTION: Neer IIB displaced fracture of the distal part of the clavicle is often treated surgically. Arthroscopy-assisted surgery was recently developed. The aim of the present study was to present an original technique of subcoracoid suture under arthroscopy, with clinical and radiological results. HYPOTHESIS: Arthroscopy-assisted subcoracoid suture in Neer IIB clavicle fracture provides satisfactory results. MATERIAL AND METHODS: Fourteen patients, with a mean age of 34.6 years (range, 24-51 years) with Neer IIB displaced clavicle fracture treated by subcoracoid suture between January 2013 and January 2017 were included. Clinical assessment comprised demographic data, weighted Constant score and Subjective Shoulder Value (SSV). Radiologic assessment comprised AP shoulder view. RESULTS: Bone healing was systematic within 3 months, except in 1 case of delayed healing. Mean follow-up was 20 months (range, 6-55 months). At last follow-up, mean weighted Constant score was 91% (range, 85-95%) and mean SSV 95% (range, 85-100%). 4 patients reported clavicle button irritation, 2 of whom asked for hardware removal. DISCUSSION: Arthroscopy-assisted subcoracoid suture provided satisfactory clinical results. There were no cases of implant failure, probably because the technique caused no iatrogenic coracoid trauma. Clavicle button irritation sometimes required hardware removal. LEVEL OF EVIDENCE: IV

Dynamical control of the convective transport behind a limiter in a magnetized laboratory plasmas

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Do double-row suture-locking anchors impact the biomechanical outcomes of rotator cuff surgery? A biomechanical study.

Introduction: Several surgical techniques for arthroscopic repair of the rotator cuff have been described in the literature. The aim of this study was to determine whether the suture thread locking method in double-row anchors influences their biomechanical properties. We compared the pullout strength of two anchors with different locking mechanisms.Methods: We performed 30 pullout tests at 135° using two different double-row anchors, an interference fit lock (5.5 mm SwiveLock) and a combination lock (5.5 mm MultiFix S). One anchor of each type was implanted on the tuberosity of a bovine humeral bone.Results: Mean pullout strength was 239.29 ± 83.73 N for the SwiveLock anchors and 253.82 ± 87.65 N for the MultiFIX S anchors, mean displacement (in millimeters) was 28 ± 9 and 30 ± 12, respectively which were not statistically significantly different.Conclusion: The addition of an internal lock in the double-row suture-locking anchor did not improve the biomechanical properties in a pullout test of 135°

Do double-row suture-locking anchors impact the biomechanical outcomes of rotator cuff surgery? A biomechanical study

International audienceIntroduction: Several surgical techniques for arthroscopic repair of the rotator cuff have been described in the literature. The aim of this study was to determine whether the suture thread locking method in double-row anchors influences their biomechanical properties. We compared the pullout strength of two anchors with different locking mechanisms.Introduction: Several surgical techniques for arthroscopic repair of the rotator cuff have been described in the literature. The aim of this study was to determine whether the suture thread locking method in double-row anchors influences their biomechanical properties. We compared the pullout strength of two anchors with different locking mechanisms.Methods: We performed 30 pullout tests at 135° using two different double-row anchors, an interference fit lock (5.5 mm SwiveLock) and a combination lock (5.5 mm MultiFix S). One anchor of each type was implanted on the tuberosity of a bovine humeral bone.Results: Mean pullout strength was 239.29 ± 83.73 N for the SwiveLock anchors and 253.82 ± 87.65 N for the MultiFIX S anchors, mean displacement (in millimeters) was 28 ± 9 and 30 ± 12, respectively which were not statistically significantly different.Conclusion: The addition of an internal lock in the double-row suture-locking anchor did not improve the biomechanical properties in a pullout test of 135