Long-term monitoring of post-stroke plasticity after transient cerebral ischemia in mice using in vivo and ex vivo diffusion tensor MRI.

WE USED A MURINE MODEL OF TRANSIENT FOCAL CEREBRAL ISCHEMIA TO STUDY: 1) in vivo DTI long-term temporal evolution of the apparent diffusion coefficient (ADC) and diffusion fractional anisotropy (FA) at days 4, 10, 15 and 21 after stroke 2) ex vivo distribution of a plasticity-related protein (GAP-43) and its relationship with the ex vivo DTI characteristics of the striato-thalamic pathway (21 days). All animals recovered motor function. In vivo ADC within the infarct was significantly increased after stroke. In the stroke group, GAP-43 expression and FA values were significantly higher in the ipsilateral (IL) striatum and contralateral (CL) hippocampus compared to the shams. DTI tractography showed fiber trajectories connecting the CL striatum to the stroke region, where increased GAP43 and FA were observed and fiber tracts from the CL striatum terminating in the IL hippocampus.Our data demonstrate that DTI changes parallel histological remodeling and recovery of function.

Long duration response to levodopa in advanced Parkinson's disease patients treated with subthalamic deep brain stimulation

Résumé La levodopa (LD) est le traitement antiparkinsonien le plus efficace et le plus répandu. Son effet est composé d'une réponse de courte (quelques heures) et de longue durée (jours à semaines). La persistance de cette dernière dans les phases avancées de la maladie de Parkinson est controversée, et sa mesure directe n'a jamais été faite en raison des risques liés à un sevrage complet de LD. La stimulation du noyau sous-thalamique est un nouveau traitement neurochirurgical de la maladie de Parkinson, indiqué dans les formes avancées, qui permet l'arrêt complet du traitement médicamenteux chez certains patients. Nous avons étudié 30 patients qui ont bénéficié d'une telle stimulation, et les avons évalués avant l'intervention sans médicaments, et à 6 mois postopératoires, sans médicaments et sans stimulation. Chez 19 patients, la médication a pu être complètement arrêtée, alors qu'elle a dû être réintroduite chez les 11 patients restants. Au cours des 6 mois qui ont suivi l'intervention, le parkinsonisme s'est aggravé de façon significative dans le groupe sans LD, et non dans le groupe avec LD. Cette différence d'évolution s'explique par la perte de l'effet à long terme de la LD dans le groupe chez qui ce médicament a pu être arrêté. En comparant cette aggravation à la magnitude de l'effet à court terme, la réponse de longue durée correspond environ à 80 pourcent de la réponse de courte durée, et elle lui est inversement corrélée. Parmi les signes cardinaux de la maladie, la réponse de longue durée affecte surtout la bradycinésie et la rigidité, mais pas le tremblement ni la composante axiale. La comparaison du parkinsonisme avec traitement (stimulation et LD si applicable) ne montre aucune différence d'évolution entre les 2 groupes, suggérant que la stimulation compense tant la réponse de courte que de longue durée. Notre travail montre que la réponse de longue durée à la LD demeure significative chez les patients parkinsoniens après plus de 15 ans d'évolution, et suggère que la stimulation du noyau sous-thalamique compense les réponses de courte et de longue durée. Abstract Background: Long duration response to levodopa is supposed to decrease with Parkinson's disease (PD) progression, but direct observation of this response in advanced PD has never been performed. Objective: To study the long duration response to levodopa in advanced PD patients treated with subthalamic deep-brain stimulation. Design and settings: We studied 30 consecutive PD patients who underwent subthalamic deep-brain stimulation. One group had no antiparkinsonian treatment since surgery (no levodopa), while medical treatment had to be reinitiated in the other group (levodopa). Main outcome measures: motor Unified Parkinson's Disease Rating Scale (UPDRS). Results: In comparison with preoperative assessment, evaluation six months postoperatively with stimulation turned off for three hours found a worsening of the motor part of UPDRS in the no-levodopa group. This worsening being absent in the levodopa group, it most probably reflected the loss of the long duration response to levodopa in the no-levodopa group. Stimulation turned on, postoperative motor UPDRS in both groups were similar to preoperative on medication scores, suggesting that subthalamic deep-brain stimulation compensated for both the short and long duration responses to levodopa. Conclusions: Our results suggest that the long duration response to levodopa remains significant even in advanced PD, and that subthalamic deep-brain stimulation compensates for both the short and the long duration resposes to levodopa.

DFM(A)-Aspects of an Advanced Cable Gland Design

Nowadays typical motor junction boxes do not incorporate cable glands, which would provide good electrical performance interms of electromagnetic compatibility. In this paper, a manufacturability and assembly analysis for the new construction of a rigid body feeder cable junction of an electric motor is presented especially for converter drives (practical tests were carried out at LUT during 2007). Although the cable junction should also clamp the cable to provide enough tensile strength, the phase conductors should not get squashed by the groundingconnection. In order to ensure good performance in an electrical mean especially in converter drives, the grounding of the cable should be connected 360 degrees around the cable. In this paper, following manufacturing technologies are discussed: traditional turning, precision and centrifugal casting, and rotation moulding. DFM(A)-aspects are presented in detail.

ACACIA: an agent-based program for simulating behavior to reach long-term goals

We present ACACIA, an agent-based program implemented in Java StarLogo 2.0 that simulates a two-dimensional microworld populated by agents, obstacles and goals. Our program simulates how agents can reach long-term goals by following sensorial-motor couplings (SMCs) that control how the agents interact with their environment and other agents through a process of local categorization. Thus, while acting in accordance with this set of SMCs, the agents reach their goals through the emergence of global behaviors. This agent-based simulation program would allow us to understand some psychological processes such as planning behavior from the point of view that the complexity of these processes is the result of agent-environment interaction.

Extending body space in immersive virtual reality: a very long arm illusion

Recent studies have shown that a fake body part can be incorporated into human body representation through synchronous multisensory stimulation on the fake and corresponding real body part- the most famous example being the Rubber Hand Illusion. However, the extent to which gross asymmetries in the fake body can be assimilated remains unknown. Participants experienced, through a head-tracked stereo head-mounted display a virtual body coincident with their real body. There were 5 conditions in a between-groups experiment, with 10 participants per condition. In all conditions there was visuo-motor congruence between the real and virtual dominant arm. In an Incongruent condition (I), where the virtual arm length was equal to the real length, there was visuo-tactile incongruence. In four Congruent conditions there was visuo-tactile congruence, but the virtual arm lengths were either equal to (C1), double (C2), triple (C3) or quadruple (C4) the real ones. Questionnaire scores and defensive withdrawal movements in response to a threat showed that the overall level of ownership was high in both C1 and I, and there was no significant difference between these conditions. Additionally, participants experienced ownership over the virtual arm up to three times the length of the real one, and less strongly at four times the length. The illusion did decline, however, with the length of the virtual arm. In the C2-C4 conditions although a measure of proprioceptive drift positively correlated with virtual arm length, there was no correlation between the drift and ownership of the virtual arm, suggesting different underlying mechanisms between ownership and drift. Overall, these findings extend and enrich previous results that multisensory and sensorimotor information can reconstruct our perception of the body shape, size and symmetry even when this is not consistent with normal body proportions.

Clinically meaningful parameters of progression and long-term outcome of Parkinson disease: An international consensus statement.

Parkinson disease (PD) is associated with a clinical course of variable duration, severity, and a combination of motor and non-motor features. Recent PD research has focused primarily on etiology rather than clinical progression and long-term outcomes. For the PD patient, caregivers, and clinicians, information on expected clinical progression and long-term outcomes is of great importance. Today, it remains largely unknown what factors influence long-term clinical progression and outcomes in PD; recent data indicate that the factors that increase the risk to develop PD differ, at least partly, from those that accelerate clinical progression and lead to worse outcomes. Prospective studies will be required to identify factors that influence progression and outcome. We suggest that data for such studies is collected during routine office visits in order to guarantee high external validity of such research. We report here the results of a consensus meeting of international movement disorder experts from the Genetic Epidemiology of Parkinson's Disease (GEO-PD) consortium, who convened to define which long-term outcomes are of interest to patients, caregivers and clinicians, and what is presently known about environmental or genetic factors influencing clinical progression or long-term outcomes in PD. We propose a panel of rating scales that collects a significant amount of phenotypic information, can be performed in the routine office visit and allows international standardization. Research into the progression and long-term outcomes of PD aims at providing individual prognostic information early, adapting treatment choices, and taking specific measures to provide care optimized to the individual patient's needs.

Long-term professional performance of minimally invasive surgery post-graduates

OBJECTIVE: to evaluate the contribution of a post-graduation program in surgeons professional careers. METHODS: participants were asked to answer a questionnaire with questions related to possible changes in their professional performance after the end of the course. RESULTS: forty-three (76.7%) of the 56 participants eligible for the study responded to the questionnaires. Most participants, 32 (74.4%), had previous contact with laparoscopic surgery; however, only 14 (32.5%) reported the experience as primary surgeon. The expectations on the course were reached or exceeded for 36 (83.7%) participants. Thirty-seven (86%) incorporated minimally invasive procedures in their daily surgical practice, 37 (86%) reported improvements in their income above 10% and 12% reported income increase of over 100%, directly related to their increase of laparoscopic activity. CONCLUSION: the program in minimally invasive surgery provides a high level of satisfaction to its participants, enables them to perform more complex technical procedures, such as sutures, and improves their professional economic performance.

Motor behavioral abnormalities and histopathological findings of Wistar rats inoculated with HTLV-1-infected MT2 cells

The objective of the present study was to describe motor behavioral changes in association with histopathological and hematological findings in Wistar rats inoculated intravenously with human T-cell lymphotropic virus type 1 (HTLV-1)-infected MT2 cells. Twenty-five 4-month-old male rats were inoculated with HTLV-1-infected MT2 cells and 13 control rats were inoculated with normal human lymphocytes. The behavior of the rats was observed before and 5, 10, 15, and 20 months after inoculation during a 30-min/rat testing time for 5 consecutive days. During each of 4 periods, a subset of rats was randomly chosen to be sacrificed in order to harvest the spinal cord for histopathological analysis and to obtain blood for serological and molecular studies. Behavioral analyses of the HTLV-1-inoculated rats showed a significant decrease of climbing, walking and freezing, and an increase of scratching, sniffing, biting, licking, and resting/sleeping. Two of the 25 HTLV-1-inoculated rats (8%) developed spastic paraparesis as a major behavioral change. The histopathological changes were few and mild, but in some cases there was diffuse lymphocyte infiltration. The minor and major behavioral changes occurred after 10-20 months of evolution. The long-term observation of Wistar rats inoculated with HTLV-1-infected MT2 cells showed major (spastic paraparesis) and minor motor abnormalities in association with the degree of HTLV-1-induced myelopathy.

Influence of cueing on the preparation and execution of untrained and trained complex motor responses

This study investigated the influence of cueing on the performance of untrained and trained complex motor responses. Healthy adults responded to a visual target by performing four sequential movements (complex response) or a single movement (simple response) of their middle finger. A visual cue preceded the target by an interval of 300, 1000, or 2000 ms. In Experiment 1, the complex and simple responses were not previously trained. During the testing session, the complex response pattern varied on a trial-by-trial basis following the indication provided by the visual cue. In Experiment 2, the complex response and the simple response were extensively trained beforehand. During the testing session, the trained complex response pattern was performed in all trials. The latency of the untrained and trained complex responses decreased from the short to the medium and long cue-target intervals. The latency of the complex response was longer than that of the simple response, except in the case of the trained responses and the long cue-target interval. These results suggest that the preparation of untrained complex responses cannot be completed in advance, this being possible, however, for trained complex responses when enough time is available. The duration of the 1st submovement, 1st pause and 2nd submovement of the untrained and the trained complex responses increased from the short to the long cue-target interval, suggesting that there is an increase of online programming of the response possibly related to the degree of certainty about the moment of target appearance.

The influence of high cable penetration in distribution networks on earth fault currents and the operation of relay protection.

Recent Storms in Nordic countries were a reason of long power outages in huge territories. After these disasters distribution networks' operators faced with a problem how to provide adequate quality of supply in such situation. The decision of utilization cable lines rather than overhead lines were made, which brings new features to distribution networks. The main idea of this work is a complex analysis of medium voltage distribution networks with long cable lines. High value of cable’s specific capacitance and length of lines determine such problems as: high values of earth fault currents, excessive amount of reactive power flow from distribution to transmission network, possibility of a high voltage level at the receiving end of cable feeders. However the core tasks was to estimate functional ability of the earth fault protection and the possibility to utilize simplified formulas for operating setting calculations in this network. In order to provide justify solution or evaluation of mentioned above problems corresponding calculations were made and in order to analyze behavior of relay protection principles PSCAD model of the examined network have been created. Evaluation of the voltage rise in the end of a cable line have educed absence of a dangerous increase in a voltage level, while excessive value of reactive power can be a reason of final penalty according to the Finish regulations. It was proved and calculated that for this networks compensation of earth fault currents should be implemented. In PSCAD models of the electrical grid with isolated neutral, central compensation and hybrid compensation were created. For the network with hybrid compensation methodology which allows to select number and rated power of distributed arc suppression coils have been offered. Based on the obtained results from experiments it was determined that in order to guarantee selective and reliable operation of the relay protection should be utilized hybrid compensation with connection of high-ohmic resistor. Directional and admittance based relay protection were tested under these conditions and advantageous of the novel protection were revealed. However, for electrical grids with extensive cabling necessity of a complex approach to the relay protection were explained and illustrated. Thus, in order to organize reliable earth fault protection is recommended to utilize both intermittent and conventional relay protection with operational settings calculated by the use of simplified formulas.

A possible role for intrinsic calcium buffers in the long- term adaptation of crayfish neurons

Increasing the impulse activity of neurons in vivo over 3 or more days causes a reduction in transmitter release that persists for days or weeks (eg. Mercier and Atwood, 1989). This effect is usually accompanied by decreased synaptic fatigue. These two changes involve presynaptic mechanisms and indicate "long-term adaptation" (LTA) of nerve terminals. Previous experiments have shown that LTA requires extracellular calcium and protein synthesis (eg. Hong and Lnenicka, Soc. Neurosci. Abstr. 17:1322) and appears to involve communication between the cell body and the nerve terminals. The present study examines the possibility that the reduction in transmitter release is caused by an -increase in the calcium buffering ability within the nerve terminals. It examines the responses of adapted and control nerve terminals to exogenously applied calcium buffer, BAPTA-AM, which decreases transmitter release (Robitialle and Charlton, 1992). If LTA increases intrinsic Ca2+-buffering, the membrane permeant form of BAPTA should have less effect on adapted nerve terminals than on controls. Experiments are performed on the phasic abdominal extensor motor neurons of the crayfish, Procambarns clarkii. BAPTA-AM decreases excitatory postsynaptic potentials (EPSP's) of the phasic extensor muscles in a dosedependent manner between 5 and 50 JLM. LTA is elicited by in vivo stimulation at 2.5 Hz for 2-4 h per day over 3 days, which reduces EPSP's by over 50%. Experiments indicate that BAPTA-AM produces no significant change in EPSP reduction in adapted neurons when compared to controls. These results do not support the hypothesis that increased daily activity alters rapid intrinsic calcium buffers, that are able to reduce transmitter output in the same manner as BAPTA.

Long-term effects of sports concussion

Questions : Cette thèse visait à répondre à deux questions fondamentales : 1) Est-ce que les athlètes qui présentent un historique de commotions cérébrales du sport en conservent des effets délétères à long terme? ; et 2) Est-ce que les effets néfastes des commotions cérébrales récurrentes sur le fonctionnement tant cognitif que moteur sont cumulatifs? Devis expérimental : À l’aide d’un plan d’investigation double-cohorte réalisé avec un groupe d’athlètes évoluant au niveau universitaire et un autre formé d’anciens athlètes universitaires testés plus de trois décennies plus tard, les quatre études qui composent cette thèse ont employé des méthodes raffinées d’investigation des fonctions cognitives et motrices pour en déceler des atteintes persistantes. Méthodologie : Les potentiels évoqués cognitifs ainsi que les tests neuropsychologiques ont permis de sonder le fonctionnement cognitif de ces athlètes alors que la stimulation magnétique transcrânienne, une plateforme de force permettant de mesurer la stabilité posturale ainsi qu’un système d’enregistrement tridimensionnel des mouvements rapides alternatifs ont servi à l’évaluation de l’intégrité du système moteur. Résultats : Cette thèse a permis de déceler des altérations persistentes et cumulatives des fonctions cognitives et motrices. De plus, ces subtiles atteintes observées chez les jeunes athlètes, affectant essentiellement des marqueurs neurophysiologiques sous-cliniques du fonctionnement cognitif et moteur, s’étaient accentuées chez les anciens athlètes universitaires qui montraient un déclin quantifiable tant des fonctions cognitives que motrices. Discussion : Ces résultats suggèrent d’une part que les commotions cérébrales du sport entraînent des altérations cognitives et motrices chroniques qui s’accentuent en fonction du nombre de commotions cérébrales subies. D’autre part, les effets délétères des commotions cérébrales du sport sur le fonctionnement cognitif et moteur combinés à ceux associés au processus de vieillissement entraînent un déclin cognitif et moteur quantifiable en comparaison aux anciens athlètes n’ayant jamais subi de commotions cérébrales.

Neural substrates and functional connectivity associated with sleep-dependent and independent consolidation of new motor skills

La mémoire n’est pas un processus unitaire et est souvent divisée en deux catégories majeures: la mémoire déclarative (pour les faits) et procédurale (pour les habitudes et habiletés motrices). Pour perdurer, une trace mnésique doit passer par la consolidation, un processus par lequel elle devient plus robuste et moins susceptible à l’interférence. Le sommeil est connu comme jouant un rôle clé pour permettre le processus de consolidation, particulièrement pour la mémoire déclarative. Depuis plusieurs années cependant, son rôle est aussi reconnu pour la mémoire procédurale. Il est par contre intéressant de noter que ce ne sont pas tous les types de mémoire procédurale qui requiert le sommeil afin d’être consolidée. Entre autres, le sommeil semble nécessaire pour consolider un apprentissage de séquences motrices (s’apparentant à l’apprentissage du piano), mais pas un apprentissage d’adaptation visuomotrice (tel qu’apprendre à rouler à bicyclette). Parallèlement, l’apprentissage à long terme de ces deux types d’habiletés semble également sous-tendu par des circuits neuronaux distincts; c’est-à-dire un réseau cortico-striatal et cortico-cérébelleux respectivement. Toutefois, l’implication de ces réseaux dans le processus de consolidation comme tel demeure incertain. Le but de cette thèse est donc de mieux comprendre le rôle du sommeil, en contrôlant pour le simple passage du temps, dans la consolidation de ces deux types d’apprentissage, à l’aide de l’imagerie par résonnance magnétique fonctionnelle et d’analyses de connectivité cérébrale. Nos résultats comportementaux supportent l’idée que seul l’apprentissage séquentiel requiert le sommeil pour déclencher le processus de consolidation. Nous suggérons de plus que le putamen est fortement associé à ce processus. En revanche, les performances d’un apprentissage visuomoteur s’améliorent indépendamment du sommeil et sont de plus corrélées à une plus grande activation du cervelet. Finalement, en explorant l’effet du sommeil sur la connectivité cérébrale, nos résultats démontrent qu’en fait, un système cortico-striatal semble être plus intégré suite à la consolidation. C’est-à-dire que l’interaction au sein des régions du système est plus forte lorsque la consolidation a eu lieu, après une nuit de sommeil. En opposition, le simple passage du temps semble nuire à l’intégration de ce réseau cortico-striatal. En somme, nous avons pu élargir les connaissances quant au rôle du sommeil pour la mémoire procédurale, notamment en démontrant que ce ne sont pas tous les types d’apprentissages qui requièrent le sommeil pour amorcer le processus de consolidation. D’ailleurs, nous avons également démontré que cette dissociation de l’effet du sommeil est également reflétée par l’implication de deux réseaux cérébraux distincts. À savoir, un réseau cortico-striatal et un réseau cortico-cérébelleux pour la consolidation respective de l’apprentissage de séquence et d’adaptation visuomotrice. Enfin, nous suggérons que la consolidation durant le sommeil permet de protéger et favoriser une meilleure cohésion au sein du réseau cortico-striatal associé à notre tâche; un phénomène qui, s’il est retrouvé avec d’autres types d’apprentissage, pourrait être considéré comme un nouveau marqueur de la consolidation.

Policy gradient based Reinforcement Learning for real autonomous underwater cable tracking

This paper proposes a field application of a high-level reinforcement learning (RL) control system for solving the action selection problem of an autonomous robot in cable tracking task. The learning system is characterized by using a direct policy search method for learning the internal state/action mapping. Policy only algorithms may suffer from long convergence times when dealing with real robotics. In order to speed up the process, the learning phase has been carried out in a simulated environment and, in a second step, the policy has been transferred and tested successfully on a real robot. Future steps plan to continue the learning process on-line while on the real robot while performing the mentioned task. We demonstrate its feasibility with real experiments on the underwater robot ICTINEU AUV

Estimulacion magnetica trascraneal en el desempeno motor en enfermedades del sistema nervioso central: Revision Sistematica

Introducción: El uso de la estimulación cerebral no invasiva en procesos de rehabilitación es de gran interés, por cuanto con mediación tecnológica se generan nuevas posibilidades de recuperación motora, a partir de la activación de la corteza cerebral. El objetivo del estudio es establecer la evidencia del uso terapéutico de la EMT, relacionado con el desempeño motor de pacientes con enfermedades del sistema nervioso central. Metodología: Se realizó una revisión sistemática de la literatura. Se incluyeron 10 estudios en el análisis cualitativo que incluyó la evaluación de calidad con la escala de Jadad y del riesgo de sesgo con la herramienta Cochrane. Fueron excluidos 1613 estudios. Se aplicó el protocolo del estudio para la extracción, revisión y validez de los estudios incluidos. Resultados: La evidencia disponible muestra resultados positivos del uso terapéutico de la EMT en el desempeño motor en aspectos como la aceleración, la fuerza de pinza y de agarre, la estabilidad y la fuerza muscular, así como una mejor velocidad de la marcha y una disminución en la frecuencia y severidad de los espasmos. Discusión: La EMT puede constituir una estrategia terapéutica para mejorar el desempeño motor en pacientes con ECV, Lesión Medular y enfermedad de Parkinson, que requiere más investigación por la heterogeneidad de los diseños y medidas de descenlace utilizados, así como por la alta variabilidad interindividual que hace complejo estandarizar los protocolos de su uso terapéutico.