Avaliação do desempenho da paligorsquita modificada e do carvão da pirólise do lodo de esgoto no processo de degradação fotocatalítica do fenol

The uncontrolled disposal of wastewaters containing phenolic compounds by the industry has caused irreversible damage to the environment. Because of this, it is now mandatory to develop new methods to treat these effluents before they are disposed of. One of the most promising and low cost approaches is the degradation of phenolic compounds via photocatalysis. This work, in particular, has as the main goal, the customization of a bench scale photoreactor and the preparation of catalysts via utilization of char originated from the fast pyrolysis of sewage sludge. The experiments were carried out at constant temperature (50°C) under oxygen (410, 515, 650 and 750 ml min-1). The reaction took place in the liquid phase (3.4 liters), where the catalyst concentration was 1g L-1 and the initial concentration of phenol was 500 mg L-1 and the reaction time was set to 3 hours. A 400 W lamp was adapted to the reactor. The flow of oxygen was optimized to 650 ml min-1. The pH of the liquid and the nature of the catalyst (acidified and calcined palygorskite, palygorskite impregnated with 3.8% Fe and the pyrolysis char) were investigated. The catalytic materials were characterized by XRD, XRF, and BET. In the process of photocatalytic degradation of phenol, the results showed that the pH has a significant influence on the phenol conversion, with best results for pH equal to 5.5. The phenol conversion ranged from 51.78% for the char sewage sludge to 58.02% (for palygorskite acidified calcined). Liquid samples analyzed by liquid chromatography and the following compounds were identified: hydroquinone, catechol and maleic acid. A mechanism of the reaction was proposed, whereas the phenol is transformed into the homogeneous phase and the others react on the catalyst surface. For the latter, the Langmuir-Hinshelwood model was applied, whose mass balances led to a system of differential equations and these were solved using numerical methods in order to get estimates for the kinetic and adsorption parameters. The model was adjusted satisfactorily to the experimental results. From the proposed mechanism and the operating conditions used in this study, the most favored step, regardless of the catalyst, was the acid group (originated from quinone compounds), being transformed into CO2 and water, whose rate constant k4 presented value of 0.578 mol L-1 min-1 for acidified calcined palygorskite, 0.472 mol L-1 min-1 for Fe2O3/palygorskite and 1.276 mol L-1 min-1 for the sludge to char, the latter being the best catalyst for mineralization of acid to CO2 and water. The quinones were adsorbed to the acidic sites of the calcined palygorskite and Fe2O3/palygorskite whose adsorption constants were similar (~ 4.45 L mol-1) and higher than that of the sewage sludge char (3.77 L mol-1).

Avaliação das Funções Executivas em Dependentes Químicos

The aim of this study was to investigate possible alterations in attentive functions and mental flexibility in individuals diagnosed with Addiction. The sample (n=40) was located for convenience, and included 20 individuals with addiction behaviors (G1), and 20 individuals who do not use harmfully psychoactive substances (G2). Assessment instruments used were: Experimental and Computerized Test of Continuous Performance, and the Wisconsin Card Sorting Test. It was concluded that individuals in the G1 group had a poorer performance in all categories analyzed on the Wisconsin Card Sorting Test and in reaction time on the Experimental and Computerized Test (p<0,05), showing a deficit in mental flexibility and attentive functions, which may have direct implications on addictive behaviors and treatment.

Retinal microvascular dysfunction occurs similarly in Alzheimer's disease and primary open angle glaucoma patients

Purpose: The exact nature of the relationship between Alzheimer’s disease (AD) and primary open angle glaucoma (POAG) is still the subject of debate. One factor attributed to the aetiology of both conditions is vascular dysfunction. This study aimed to investigate the similarities and differences in retinal microvascular function between mild AD patients, early stage POAG patients and healthy controls Methods: Retinal vessel reactivity to flickering light was assessed in 10 AD, 19 POAG and 22 healthy age matched control patients by means of dynamic retinal vessel analysis (DVA, IMEDOS, GmbH, Jena, Germany) according to an established protocol. All patients additionally underwent BP measurements and blood analysis for glucose and lipid metabolism markers Results: AD and POAG patients demonstrated comparable alterations in retinal artery reactivity, in the form of an increased arterial reaction time (RT) to flicker light on the final flicker cycle (p=0.014), which was not replicated in the healthy age and cardiovascular risk matched controls (p>0.05). Furthermore, the sequential changes in RT on progressing from flicker one to flicker three were found to differ between healthy controls and the two disease groups (p=0.001) Conclusions: AD and POAG patients demonstrate comparable signs of vascular dysfunction in their retinal arteries at the early stages of their disease process. These comparable signs may reflect similarities in the pathophysiological processes that occur in the development of both conditions

Differential activation in temporal, cingulate and prefrontal cortices during response inhibition in bipolar disorder

Background: Increased impulsivity and aberrant response inhibition have been observed in bipolar disorder (BD). This study examined the functional abnormalities and underlying neural processes during response inhibition in BD, and its relationship to impulsivity. Methods: We assessed impulsivity using the Barratt Impulsiveness Scale (BIS) and, using functional magnetic resonance imaging (fMRI), measured neural activity in response to an Affective Go-NoGo Task, consisting of emotional facial stimuli (fear, happy, anger faces) and non-emotional control stimuli (neutral female and male faces) in euthymic BD (n=23) and healthy individuals (HI; n=25). Results: BD patients were significantly more impulsive, yet did not differ from HI on accuracy or reaction time on the emotional go/no-go task. Comparing neural patterns of activation when processing emotional Go versus emotional NoGo trials yielded increased activation in BD within temporal and cingulate cortices and within prefrontal-cortical regions in HI. Furthermore, higher BIS scores for BD were associated with slower reaction times, and indicative of compensatory cognitive strategies to counter increased impulsivity. Conclusions: These findings illustrate cognition-emotion interference in BD and the observed differences in neural activation indicate potentially altered emotion modulation. Increased activation in brain regions previously shown in emotion regulation and response inhibition tasks could represent a disease-specific marker for BD

Overweight status is associated with extensive signs of microvascular dysfunction and cardiovascular risk

The aim of this present study was to investigate if overweight individuals exhibit signs of vascular dysfunction associated with a high risk for cardiovascular disease (CVD). One hundred lean and 100 overweight participants were recruited for the present study. Retinal microvascular function was assessed using the Dynamic Retinal Vessel Analyser (DVA), and systemic macrovascular function by means of flow-mediated dilation (FMD). Investigations also included body composition, carotid intimal-media thickness (c-IMT), ambulatory blood pressure monitoring (BP), fasting plasma glucose, triglycerides (TG), cholesterol levels (HDL-C and LDL-C), and plasma von Willebrand factor (vWF). Overweight individuals presented with higher right and left c-IMT (p = 0.005 and p = 0.002, respectively), average 24-h BP values (all p <0.001), plasma glucose (p = 0.008), TG (p = 0.003), TG: HDL-C ratio (p = 0.010), and vWF levels (p = 0.004). Moreover, overweight individuals showed lower retinal arterial microvascular dilation (p = 0.039) and baseline-corrected flicker (bFR) responses (p = 0.022), as well as, prolonged dilation reaction time (RT, p = 0.047). These observations emphasise the importance of vascular screening and consideration of preventive interventions to decrease vascular risk in all individuals with adiposity above normal range.

Degradation rates and productivity signals of organic-walled dinoflagellate cyst species in surface sediment samples

To understand the role of the ocean within the global carbon cycle, detailed information is required on key-processes within the marine carbon cycle; bio-production in the upper ocean, export of the produced material to the deep ocean and the storage of carbon in oceanic sediments. Quantification of these processes requires the separation of signals of net primary production and the rate of organic matter decay as reflected in fossil sediments. This study examines the large differences in degradation rates of organic-walled dinoflagellate cyst species to separate these degradation and productivity signals. For this, accumulation rates of cyst species known to be resistant (R-cysts) or sensitive (S-cysts) to aerobic degradation of 62 sites are compared to mean annual chlorophyll-a, sea-surface temperature, sea-surface salinity, nitrate and phosphate concentrations of the upper waters and deep-water oxygen concentrations. Furthermore, the degradation of sensitive cysts, as expressed by the degradation constant k and reaction time t, has been related to bottom water [O2]. The studied sediments were taken from the Arabian Sea, north-western African Margin (North Atlantic), western-equatorial Atlantic Ocean/Caraibic, south-western African margin (South Atlantic) and Southern Ocean (Atlantic sector). Significant relationships are observed between (a) accumulation rates of R-cysts and upper water chlorophyll-a concentrations, (b) accumulation rates of S-cysts and bottom water [O2] and (c) degradation rates of S-cysts (kt) and bottom water [O2]. Relationships that are extremely weak or are clearly insignificant on all confidence intervals are between (1) S-cyst accumulation rates and chlorophyll-a concentrations, sea-surface temperature (SST), sea-surface salinity (SSS), phosphate concentrations (P) and nitrate concentrations (N), (2) between R-cyst accumulation rates and bottom water [O2], SST, SSS, P and N, and between (3) kt and water depth. Co-variance is present between the parameters N and P, N, P and chlorophyll-a, oxygen and water depth. Correcting for this co-variance does not influence the significance of the relationship given above. The possible applicability of dinoflagellate cyst degradation to estimate past net primary production and deep ocean ventilation is discussed.

Osmium concentrations and isotope ratios of ODP Hole 207-1260B and the Furlo section

Oceanic anoxic events (OAEs) were episodes of widespread marine anoxia during which large amounts of organic carbon were buried on the ocean floor under oxygen-deficient bottom waters (Schlanger and Jenkyns, 1976; Schlanger et al., 1987). OAE2, occurring at the Cenomanian/Turonian boundary (about 93.5 Myr ago) (Gradstein et al., 2004), is the most widespread and best defined OAE of the mid-Cretaceous. Although the enhanced burial of organic matter can be explained either through increased primary productivity or enhanced preservation scenarios (Schlanger and Jenkyns, 1976; Schlanger et al., 1987). the actual trigger mechanism, corresponding closely to the onset of these episodes of increased carbon sequestration, has not been clearly identified. It has been postulated that large-scale magmatic activity initially triggered OAE2 (Sinton and Duncan, 1997; Kerr, 1998, doi:10.1144/gsjgs.155.4.0619), but a direct proxy of magmatism preserved in the sedimentary record coinciding closely with the onset of OAE2 has not yet been found. Here we report seawater osmium isotope ratios in organic-rich sediments from two distant sites. We find that at both study sites the marine osmium isotope record changes abruptly just at or before the onset of OAE2. Using a simple two-component mixing equation, we calculate that over 97 per cent of the total osmium content in contemporaneous seawater at both sites is magmatic in origin, a ~30-50-fold increase relative to pre-OAE conditions. Furthermore, the magmatic osmium isotope signal appears slightly before the OAE2 -as indicated by carbon isotope ratios- suggesting a time-lag of up to ~23 kyr between magmatism and the onset of significant organic carbon burial, which may reflect the reaction time of the global ocean system. Our marine osmium isotope data are indicative of a widespread magmatic pulse at the onset of OAE2, which may have triggered the subsequent deposition of large amounts of organic matter.

Robotic Outcome Assessment in a Non-Human Primate Model of Middle Cerebral Artery Stroke

Stroke is a prevalent disorder with immense socioeconomic impact. A variety of chronic neurological deficits result from stroke. In particular, sensorimotor deficits are a significant barrier to achieving post-stroke independence. Unfortunately, the majority of pre-clinical studies that show improved outcomes in animal stroke models have failed in clinical trials. Pre-clinical studies using non-human primate (NHP) stroke models prior to initiating human trials are a potential step to improving translation from animal studies to clinical trials. Robotic assessment tools represent a quantitative, reliable, and reproducible means to assess reaching behaviour following stroke in both humans and NHPs. We investigated the use of robotic technology to assess sensorimotor impairments in NHPs following middle cerebral artery occlusion (MCAO). Two cynomolgus macaques underwent transient MCAO for 90 minutes. Approximately 1.5 years following the procedure these NHPs and two non-stroke control monkeys were trained in a reaching task with both arms in the KINARM exoskeleton. This robot permits elbow and shoulder movements in the horizontal plane. The task required NHPs to make reaching movements from a centrally positioned start target to 1 of 8 peripheral targets uniformly distributed around the first target. We analyzed four movement parameters: reaction time, movement time (MT), initial direction error (IDE), and number of speed maxima to characterize sensorimotor deficiencies. We hypothesized reduced performance in these attributes during a neurobehavioural task with the paretic limb of NHPs following MCAO compared to controls. Reaching movements in the non-affected limbs of control and experimental NHPs showed bell-shaped velocity profiles. In contrast, the reaching movements with the affected limbs were highly variable. We found distinctive patterns in MT, IDE, and number of speed peaks between control and experimental monkeys and between limbs of NHPs with MCAO. NHPs with MCAO demonstrated more speed peaks, longer MTs, and greater IDE in their paretic limb compared to controls. These initial results qualitatively match human stroke subjects’ performance, suggesting that robotic neurobehavioural assessment in NHPs with stroke is feasible and could have translational relevance in subsequent human studies. Further studies will be necessary to replicate and expand on these preliminary findings.

Hypoxia-induced DNA hypermethylation in human pulmonary fibroblasts is associated with Thy-1 promoter methylation and the development of a pro-fibrotic phenotype

BACKGROUND: Pulmonary fibrosis is a debilitating and lethal disease with no effective treatment options. Understanding the pathological processes at play will direct the application of novel therapeutic avenues. Hypoxia has been implicated in the pathogenesis of pulmonary fibrosis yet the precise mechanism by which it contributes to disease progression remains to be fully elucidated. It has been shown that chronic hypoxia can alter DNA methylation patterns in tumour-derived cell lines. This epigenetic alteration can induce changes in cellular phenotype with promoter methylation being associated with gene silencing. Of particular relevance to idiopathic pulmonary fibrosis (IPF) is the observation that Thy-1 promoter methylation is associated with a myofibroblast phenotype where loss of Thy-1 occurs alongside increased alpha smooth muscle actin (α-SMA) expression. The initial aim of this study was to determine whether hypoxia regulates DNA methylation in normal human lung fibroblasts (CCD19Lu). As it has been reported that hypoxia suppresses Thy-1 expression during lung development we also studied the effect of hypoxia on Thy-1 promoter methylation and gene expression.

METHODS: CCD19Lu were grown for up to 8 days in hypoxia and assessed for global changes in DNA methylation using flow cytometry. Real-time PCR was used to quantify expression of Thy-1, α-SMA, collagen I and III. Genomic DNA was bisulphite treated and methylation specific PCR (MSPCR) was used to examine the methylation status of the Thy-1 promoter.

RESULTS: Significant global hypermethylation was detected in hypoxic fibroblasts relative to normoxic controls and was accompanied by increased expression of myofibroblast markers. Thy-1 mRNA expression was suppressed in hypoxic cells, which was restored with the demethylating agent 5-aza-2'-deoxycytidine. MSPCR revealed that Thy-1 became methylated following fibroblast exposure to 1% O2.

CONCLUSION: These data suggest that global and gene-specific changes in DNA methylation may play an important role in fibroblast function in hypoxia.

Incidence and clinicobiologic characteristics of leukemic B-cell chronic lymphoproliferative disorders with more than one B-cell clone.

Leukemic B-chronic lymphoproliferative disorders (B-CLPDs) are generally believed to derive from a monoclonal B cell; biclonality has only occasionally been reported. In this study, we have explored the incidence of B-CLPD cases with 2 or more B-cell clones and established both the phenotypic differences between the coexisting clones and the clinicobiologic features of these patients. In total, 53 B-CLPD cases with 2 or more B-cell clones were studied. Presence of 2 or more B-cell clones was suspected by immunophenotype and confirmed by molecular/genetic techniques in leukemic samples (n = 42) and purified B-cell subpopulations (n = 10). Overall, 4.8% of 477 consecutive B-CLPDs had 2 or more B-cell clones, their incidence being especially higher among hairy cell leukemia (3 of 13), large cell lymphoma (2 of 10), and atypical chronic lymphocytic leukemia (CLL) (4 of 29). In most cases the 2 B-cell subsets displayed either different surface immunoglobulin (sIg) light chain (n = 37 of 53) or different levels of the same sIg (n = 9 of 53), usually associated with other phenotypic differences. Compared with monoclonal cases, B-CLL patients with 2 or more clones had lower white blood cell (WBC) and lymphocyte counts, more frequently displayed splenomegaly, and required early treatment. Among these, the cases in which a CLL clone coexisted with a non-CLL clone were older and more often displayed B symptoms, a monoclonal component, and diffuse infiltration of bone marrow and required early treatment more frequently than cases with monoclonal CLL or 2 CLL clones.

Marqueurs électrophysiologiques des dysfonctions attentionnelles et de leur récupération suite à un traumatisme craniocérébral léger

L’objectif principal de cette thèse était d’obtenir, via l’électrophysiologie cognitive, des indices de fonctionnement post-traumatisme craniocérébral léger (TCCL) pour différents niveaux de traitement de l’information, soit l’attention sélective, les processus décisionnels visuoattentionnels et les processus associés à l’exécution d’une réponse volontaire. L’hypothèse centrale était que les mécanismes de production des lésions de même que la pathophysiologie caractérisant le TCCL engendrent des dysfonctions visuoattentionnelles, du moins pendant la période aiguë suivant le TCCL (i.e. entre 1 et 3 mois post-accident), telles que mesurées à l’aide d’un nouveau paradigme électrophysiologique conçu à cet effet. Cette thèse présente deux articles qui décrivent le travail effectué afin de rencontrer ces objectifs et ainsi vérifier les hypothèses émises. Le premier article présente la démarche réalisée afin de créer une nouvelle tâche d’attention visuospatiale permettant d’obtenir les indices électrophysiologiques (amplitude, latence) et comportementaux (temps de réaction) liés aux processus de traitement visuel et attentionnel précoce (P1, N1, N2-nogo, P2, Ptc) à l’attention visuelle sélective (N2pc, SPCN) et aux processus décisionnels (P3b, P3a) chez un groupe de participants sains (i.e. sans atteinte neurologique). Le deuxième article présente l’étude des effets persistants d’un TCCL sur les fonctions visuoattentionelles via l’obtention des indices électrophysiologiques ciblés (amplitude, latence) et de données comportementales (temps de réaction à la tâche et résultats aux tests neuropsychologiques) chez deux cohortes d’individus TCCL symptomatiques, l’une en phase subaigüe (3 premiers mois post-accident), l’autre en phase chronique (6 mois à 1 an post-accident), en comparaison à un groupe de participants témoins sains. Les résultats des articles présentés dans cette thèse montrent qu’il a été possible de créer une tâche simple qui permet d’étudier de façon rapide et peu coûteuse les différents niveaux de traitement de l’information impliqués dans le déploiement de l’attention visuospatiale. Par la suite, l’utilisation de cette tâche auprès d’individus atteints d’un TCCL testés en phase sub-aiguë ou en phase chronique a permis d’objectiver des profils d’atteintes et de récupération différentiels pour chacune des composantes étudiées. En effet, alors que les composantes associées au traitement précoce de l’information visuelle (P1, N1, N2) étaient intactes, certaines composantes attentionnelles (P2) et cognitivo-attentionnelles (P3a, P3b) étaient altérées, suggérant une dysfonction au niveau des dynamiques spatio-temporelles de l’attention, de l’orientation de l’attention et de la mémoire de travail, à court et/ou à long terme après le TCCL, ceci en présence de déficits neuropsychologiques en phase subaiguë surtout et d’une symptomatologie post-TCCL persistante. Cette thèse souligne l’importance de développer des outils diagnostics sensibles et exhaustifs permettant d’objectiver les divers processus et sous-processus cognitifs susceptible d’être atteints après un TCCL.

Proprioception in ankle sprain from exercises and bandages

Ankle sprains are the most common injuries in sports, usually causing damage to the lateral ligaments. Recurrence has as usual result permanent instability, and thus loss of proprioception. This fact, together with residual symptoms, is what is known as chronic ankle instability, CAI, or FAI, if it is functional. This problem tries to be solved by improving musculoskeletal stability and proprioception by the application of bandages and performing exercises. The aim of this study has been to review articles (meta-analisis, systematic reviews and revisions) published in 2009-2015 in PubMed, Medline, ENFISPO and BUCea, using keywords such as “sprain instability”, “sprain proprioception”, “chronic ankle instability”. Evidence affirms that there does exist decreased proprioception in patients who suffer from CAI. Rehabilitation exercise regimen is indicated as a treatment because it generates a subjective improvement reported by the patient, and the application of bandages works like a sprain prevention method limiting the range of motion, reducing joint instability and increasing confidence during exercise. As podiatrists we should recommend proprioception exercises to all athletes in a preventive way, and those with CAI or FAI, as a rehabilitation programme, together with the application of bandages. However, further studies should be generated focusing on ways of improving proprioception, and on the exercise patterns that provide the maximum benefit.

Studio della reattività del glicerol carbonato nella sintesi di derivati fenolici

Supported by the increasing sustainable awareness, glycerol carbonate has gained much interest over the last 20 years because of its versatile reactivity and as a way to valorize waste glycerol. Numerous synthesis pathways for this molecule were identified, some of them very promising and on the verge of being applied at an industrial scale. Here, we report a study aimed at valorizing glycerol carbonate as chemical intermediate, in order to synthesize 2-hydroxymethyl-1,4-benzodioxane (HMB). This molecule finds important applications as key intermediate for the synthesis of a broad class of pharmaceuticals and therapeutic agents. Concerning the presence of a stereogenic center on the hydroxymethyl group, due to the pharmaceutical importance to obtain and isolate one single enantiomer, , nowadays HMB is obtained through batch scale process, using a multi-reaction approach and starting from reagents of the chiral pool. We carried out the reaction from a solution of glycerol carbonate and catechol 2:1. In the presence of a simple basic catalyst, at high temperatures, it was possible obtain total reactants conversion and high yield to HMB in few hours reaction time. Also, in the aim of developing a process which might adhere the principles of Green Chemistry, we avoided the use of solvents. Similar results were obtained using a 1:1 feed ratio of reactants, even if selectivity to HMB decrease, due to the presence of side reactions. A complete study of the reaction mechanism is proposed in this thesis.

L'influence des oscillations en delta sur la sélection d'une action

Résumé : La capacité de décider parmi plusieurs possibilités d'actions, grâce à l'information sensorielle disponible, est essentielle à un organisme interagissant avec un environnement complexe. Les modèles actuels de sélection d'une action soutiennent que le cerveau traite continuellement l'information sensorielle afin de planifier plusieurs possibilités d'action en parallèle. Dans cette perspective, ces représentations motrices, associées à chaque possibilité d'action, sont en constante compétition entre elles. Afin qu'une alternative puisse être sélectionnée pour le mouvement, une valeur de pondération, intégrant une multitude de facteurs, doit être associée à chacun des plans moteurs afin de venir moduler la compétition. Plusieurs études se sont intéressées aux différents facteurs modulant la sélection de l'action, tels que la disposition de l'environnement, le coût des actions, le niveau de récompense, etc. Par contre, il semble qu'aucune étude n'ait rapporté ce qu'il advient lorsque la valeur de pondération de chacune des actions possibles est identique. Dans ce contexte, quel est l'élément permettant de venir moduler la sélection de l'action? De ce fait, l'objectif principal de mon projet de maitrise est d'investiguer le facteur permettant au cerveau de sélectionner une action lorsque tous les facteurs rapportés dans la littérature sont contrôlés. De récentes données ont montré que les oscillations corticales lentes dans la bande delta peuvent servir d'instrument de sélection attentionnelle en modulant l'amplitude de la réponse neuronale. Ainsi, les stimuli arrivant dans le cortex pendant une phase en delta de forte excitabilité sont amplifiés, tandis que ceux arrivant lors d'une phase en delta de faible excitabilité sont atténués. Ceci dit, il est possible que la phase en delta dans laquelle se trouve le cerveau au moment d'effectuer la sélection d'une action puisse influencer la décision. Utilisant une tâche de sélection de main, cette étude teste l'hypothèse que la sélection de la main est associée à la phase en delta des ensembles neuronaux codant le mouvement de chacune des mains, lorsque tous les facteurs connus influençant la décision sont contrôlés. L'électroencéphalographie (EEG) fut utilisée afin d'enregistrer les signaux corticaux pendant que les participants effectuaient une tâche de sélection de main dans laquelle ils devaient, à chaque essai, atteindre une cible visuelle aussi rapidement que possible en utilisant la main de leur choix. La tâche fut conçue de façon à ce que les facteurs spatiaux et biomécaniques soient contrôlés. Ceci fut réalisé enidentifiant premièrement, sur une base individuelle, l'emplacement de la cible pour laquelle les mains droite et gauche avaient une probabilité équivalente d'être choisies (point d'égalité subjective, PSE). Ensuite, dans l'expérience principale, les participants effectuaient plusieurs mouvements d'atteinte vers des cibles positionnées près et loin du PSE, toujours avec la main de leur choix. L'utilisation de cinq cibles très près du PSE a permis de collecter de nombreux essais dans lesquels la main droite et la main gauche furent sélectionnées en réponse à un même stimulus visuel. Ceci a ainsi permis d'analyser les signaux des deux cortex dans des conditions d'utilisation de la main droite et gauche, tout en contrôlant pour les autres facteurs pouvant moduler la sélection de la main. Les résultats de cette recherche révèlent que l'hémisphère cortical se trouvant dans la phase la plus excitable en delta (près du pic négatif), lors de l'apparition du stimulus, est associé à la fois à la main qui sera sélectionnée ainsi qu'au temps de réaction. Ces résultats montrent que l'excitabilité corticale momentanée (phase du signal) pourrait agir comme un facteur modulant la sélection d'une action. Dans cette optique, ces données élargissent considérablement les modèles actuels en montrant que la sélection d'une action est en partie déterminée par l'état du cerveau au moment d'effectuer un choix, d'une manière qui est indépendante de toutes les variables de décision connues.

The effect of carbohydrate mouth rinsing on fencing performance and cognitive function following fatigue-inducing fencing

This study investigated the impact that mouth rinsing carbohydrate solution has on skill-specific performance and reaction time following a fatigue inducing bout of fencing in epee fencers. Nine healthy, national level epee fencers visited a laboratory on 2 occasions, separated by a minimum of 5 days, to complete a 1-minute lunge test and Stroop test pre and post fatigue. Heart rate and ratings of perceived exertion (RPE) were recorded during completion of the fatiguing protocol. Between fights the participants mouth rinsed for 10 seconds, either 25ml of 6.7% maltodextrin solution (MALT) or water (PLAC). Blood lactate and glucose were recorded at baseline, pre- and post-testing. Results showed an increase in heart rate and overall RPE over time in both conditions. There were no differences in blood glucose (F(1,8)=.63, P=.4, ηp=.07) or blood lactate levels (F(1,8)=.12, P=.70, ηp=.01) between conditions as a function of time. There was a significant improvement in lunge test accuracy during the MALT trial (F(1,8)=5.21, P=.05, ηp=.40) with an increase from pre (81.2 ±8.3%) to post (87.6 ±9.4%), whereas there was no significant change during the placebo (pre 82.1 ±8.8%, post 78.8 ±6.4%). There were no recorded differences between conditions in response time to congruent (F(1,8)=.33, P=.58, ηp=.04) or incongruent stimuli (F(1,8)=.19, P=.68, ηp=.02). The study indicates that when fatigued mouth rinsing MALT significantly improves accuracy of skill-specific fencing performance but no corresponding influence on reaction time was observed.