Introdução: A disfagia está frequentemente assoaciada com a DP e pode levar a desidratação, perda de peso, pneumonia aspirativa, redução da qualidade de vida severa e até mesmo óbito. Apesar desses dados, os mecanismos subjacentes e a interferência de tarefas simultâneas na deglutição permanecem incertos, principalmente na população com DP que, conhecidamente, apresenta dificuldades em realizar movimentos simultâneos. Objetivo: O objetivo deste trabalho foi avaliar a interferência da dupla tarefa na biomecânica da deglutição na DP, avaliada por meio de videonasoendoscopia funcional da deglutição e videofluoroscopia da deglutição (VFD). Método: Este estudo foi dividido em dois experimentos. No primeiro experimento dez participantes com DP foram testados enquanto realizavam a deglutição e uma dupla tarefa manual por meio de VFD. Na condição de dupla tarefa, os participantes deglutiram 5ml de alimento pastoso durante oposição de polegares sequencial e não sequencial. Para o segundo estudo, avaliamos por meio de FEES, 19 pacientes pareados por sexo, idade e escolaridade com controles saudáveis (HC). A dupla tarefa empregada foi deglutir 3ml e 5ml de pastoso durante a performance de oposição de polegares não sequencial. Resultados: Os resultados mostraram efeitos funcionais significativos na segurança da deglutição entre o desempenho da tarefa isolada e na dupla tarefa por meio da VFD e FEES. Não houve correlação entre o desempenho nas testagens cognitivas e estágio da doença medido através de UPDRS (Unified Parkinson’s disease rating scale) para a MBSS e H&Y (Hoehn & Yahr) para FEES. Esses achados revelam que a avaliação e terapia necessitam de atenção e manejo considerando tarefas que podem ser competitivas para a deglutição e consequentemente comprometer a sua segurança. / Introduction: Dysphagia is often associated with PD and may lead to dehydration, weight loss, aspiration pneumonia, severely reduced quality of life and even death. Despite these data, the underlying mechanisms and the interference of simultaneous tasks on swallowing remain uncertain, especially in people with PD who known to be presents difficulties in performing simultaneous movements. Objective: The aim of this study was to evaluate the interference of the dual task in the biomechanics of swallowing in PD evaluated using Fiberoptic Endoscopic Evaluation of Swallowing (FEES) and modified barium swallowing study (MBSS). Methods: This study was divided in two protocols. In the first experiment ten participants with PD were tested while performing swallowing and a hand dual task under MBSS. In dual task condition, participants swallowed 5ml of pudding barium during the sequential and non-sequential finger tapping. For the second study, we evaluated under FEES, 19 PD patients matched for sex, age and education with healthy controls (HC). The duasl task employed was swallowing 3ml and 5 ml of pudding while performing non- sequential finger tapping. Results showed significant functional effects to swallowing safety between single and dual-task performance under MBSS and FEES. There was no correlation between performance on cognitive tests, and stage of the disease as measured by UPDRS (Unified Parkinson’s disease rating scale) for MBSS and H&Y (Hoehn & Yahr) to FEES and swallowing. These findings reveal that assessment and therapy need attention and management considering tasks that can be competitive for swallowing and therefore compromise their safety.

Estudos prévios têm indicado que o aumento da demanda de estabilidade manual induz maior estabilidade do equilíbrio corporal no controle das posturas quieta e perturbada. O presente estudo teve por objetivo avaliar o efeito da demanda de estabilidade imposta por uma tarefa manual sobre a regulação postural dinâmica em função da frequência de oscilação da base de suporte. Participaram desse estudo 20 estudantes universitários de ambos os sexos. A tarefa consistiu em manter um cilindro o mais estável possível sobre uma bandeja enquanto o equilíbrio em postura ereta era mantido em translações sinusoidais contínuas da plataforma móvel por 1 min., nas frequências de 0,4 Hz (baixa) ou 1 Hz (alta). A demanda de estabilidade manual foi manipulada por meio da disposição do cilindro. Na condição chamada de alta restrição (AR), o cilindro foi apoiado sobre sua face circular; na condição chamada de baixa restrição (BR), o cilindro foi apoiado sobre sua face plana. Os resultados mostraram que AR induziu menores amplitudes de oscilações de cabeça, centro de massa e bandeja na frequência de 0,4 Hz, porém não na frequência de 1 Hz. A análise das variáveis de coordenação revelou que na frequência de 0,4 Hz, AR levou a maiores valores de fase relativa entre as rotações cíclicas de tornozelo-quadril e tornozelo-ombro, como também na coordenação entre CM-plataforma e CP-plataforma. As análises mostraram que a condição de alta restrição também afetou o controle postural e manual na frequência de oscilação de 1 Hz, com aumento da amplitude de oscilação de CP e de rotações do ombro. Estes resultados sugerem que o controle postural dinâmico é regulado em diferentes parâmetros de maneira integrada e flexível, com interação recíproca entre os componentes da tarefa manual e postural, para atender à demanda de estabilidade imposta por uma tarefa posturomanual / Previous studies have indicated that increased steadiness constraints given by a manual task leads to gains of postural stability in quiet and perturbed standing. The aim of the present study was to evaluate the effects of manual task constraints on the regulation of dynamic postural control according to the frequency of sinusoidal translations of the base of support. Twenty university students performed a dual posturomanual task consisting of maintaining a cylinder on a handheld tray as stable as possible while maintaining the dynamic upright balance on a platform oscillating in sinusoidal translations at 0.4 Hz (low) or 1 Hz (high) frequencies during intervals of 1 min. The effects of manual task were studied through the manipulation of task constraint conditions set by positioning the cylinder supported on its round or flat side, corresponding respectively to high (HC) and low (LC) manual task constraints. Results showed that HC led to reduced oscillation amplitudes of the head, center of mass, and tray at 0.4 Hz, but not at 1 Hz. The coordination variables indicated that at 0.4 Hz, HC led to increased relative phase values between ankle-shoulder and hip-shoulder rotations, as also between center of mass-feet and center of pressure-feet oscillations in the slow oscillation frequency. Further analyses showed that the high manual task constraint also affected variables related to both postural and manual task components at 1 Hz, with increased center of pressure and shoulder rotation amplitudes of oscillation. These results suggest that dynamic postural control is regulated through different parameters in a flexible and integrated way in order to attend the stability demands imposed by a posturomanual task

A capacidade de adaptação das respostas posturais automáticas de acordo com informações do contexto indica uma interação entre dois níveis de controle, em que o processamento cognitivo de alta ordem das características de uma perturbação iminente seria capaz de modular o controle postural em níveis inferiores do sistema sensoriomotor. Os estudos aqui propostos procuram responder quais informações sobre as características da perturbação são utilizadas pelo central set para modular as respostas posturais automáticas. A tarefa estudada consistiu na recuperação do equilíbrio da postura ereta em resposta à translação da base de suporte. No Experimento 1, foi avaliada a influência de dicas visuais sobre a amplitude de deslocamento da base de suporte em sequências repetitivas ou aleatórias de perturbação. No Experimento 2, a dica de amplitude de deslocamento foi dada por meio da sequência de perturbações, comparando-se tentativas repetidas em bloco, em sequência conhecida e em sequência aleatória. No Experimento 3, foi avaliado o efeito de incerteza tanto da amplitude da perturbação quanto do tempo de aplicação da perturbação. O Experimento 4 teve como propósito avaliar a interação entre dica temporal e tarefa cognitiva concomitante à recuperação do equilíbrio. Os resultados mostram que (a) informações prévias sobre a magnitude da perturbação postural parecem ser incapazes de modular respostas posturais automáticas; (b) modulação de respostas posturais automáticas a partir de uma sequência repetitiva de perturbações aparentemente está associada à adaptação do sistema sensoriomotor e não à participação de processamento cognitivo das características físicas da perturbação iminente; (c) previsibilidade temporal da perturbação postural induz uma otimização das respostas posturais automáticas; e (d) a execução de tarefa cognitiva no momento da perturbação inibe o ganho de estabilidade de respostas posturais automáticas conferido pela dica temporal. Como conclusão, parece haver uma limitação do processamento cognitivo em modular respostas posturais automáticas. Considerando-se que o conceito de central set expressa a noção de que processamento cognitivo de dicas contextuais é capaz de otimizar respostas posturais automáticas, nossos resultados sugerem a necessidade da revisão deste conceito amplamente empregado na literatura de controle postural / Adaptability of automatic postural responses according to context information indicates an interaction between two levels of control, in which the high-order cognitive processing of the perturbation characteristics would be able to modulate postural control in lower levels of the sensorimotor system. The studies proposed here intended to scrutinize what cues about the perturbation characteristics are used by the central set to modulate the automatic postural responses. The task studied consisted in the recovery of postural equilibrium in response to a posterior translation of the support base. In Experiment 1, it was evaluated the effect of precueing the displacement amplitude of the supporting base in repetitive or random perturbation sequences. In Experiment 2, precueing of the support base displacement was provided by the sequence of perturbations, comparing repetitive trials, known sequence and random sequence. In Experiment 3, we evaluated the effect of uncertainty about amplitude and time of perturbation. Experiment 4 aimed to evaluate the interaction of temporal precueing and a concurrent cognitive task on body equilibrium recovery. Results show that (a) previous information about perturbation magnitude seems to be unable to modulate automatic postural responses; (b) modulation of automatic postural responses from a repetitive sequence of perturbations is apparently associated with an adaptation of the sensorimotor system rather than to the participation of cognitive processing of the perturbation characteristics; (c) temporal predictability of the postural perturbation induces optimization of automatic postural responses; and (d) cognitive task execution at the time of the perturbation inhibits the gain of automatic postural responses stability provided by temporal precueing. As a conclusion, there seems to be a limitation of cognitive processing to modulate automatic postural responses. Considering that the concept of central set expresses the notion that cognitive processing of a contextual precue is able to optimize automatic postural responses, our results suggest the need for revision of this conceptualization widely used in the postural control literature

La production du langage est une activité cognitive longtemps restée étudiée de manière isolée des processus cognitifs plus généraux pouvant sous-tendre sa réalisation. Notre approche a été de contribuer à la dynamique naissante d’une ouverture de la psycholinguistique aux autres domaines de la psychologie cognitive, en spécifiant les interactions qu’entretiennent les mécanismes langagiers avec les mécanismes attentionnels. Pour ce faire, nous avons notamment étudié dans quelle mesure la production d’une information linguistique isolée repose sur des mécanismes de sélection. Conjointement, nous avons tenté de mettre en évidence les mécanismes attentionnels sous-tendant ces mécanismes de sélection lexicale. Les sélections de deux types de mots grammaticaux ont été comparées : les mots de la classe ouverte et les mots de la classe fermée. Les résultats ont révélé que la sélection des deux types de mots, les mots de la classe fermée qui structurent la phrase et les mots de la classe ouverte qui lui donnent un sens, recrutent des ressources attentionnelles. Aussi, nous avons montré que l’effet d’interférence sémantique –supposé affecter un mécanisme de compétition à l’étape de sélection lexicale- peut être résolu avant l’engagement de ressources attentionnelles. Ce résultat suggère que l’effet d’interférence sémantique reflète un mécanisme situé avant la sélection lexicale. Une dernière étude s’est proposé d’explorer la dynamique temporelle de notre système de production à sélectionner plusieurs mots dans un contexte de production de séquences de mots, tel que celui de syntagmes nominaux. Les résultats chronométriques ont révélé que les mots sont sélectionnés de manière strictement séquentielle, une dynamique suggérant que le recrutement de ressources attentionnelles pour la sélection d’une information linguistique isolée peut contraindre leur agencement dans un contexte de production plus naturel. / Language production is a cognitive activity long studied in isolation from more general cognitive processes that could underlie its achievement. Our approach aimed to contribute to the emerging dynamics of the opening of psycholinguistics to other domains of cognitive psychology by specifying how linguistic mechanisms interact with attentional mechanisms. To do so, we first investigated to which extent producing a single linguistic unit relies on selection mechanisms. Also, we highlighted the attentional mechanisms underlying these lexical selection mechanisms: The selections of two types of grammatical words were compared: open- and closed- class words. Results revealed that the selections of both, closed-class words structuring the phrase, and open-class words conveying meaning, require attentional resources. In a third study, we showed that the semantic interference effect - affecting a competition mechanism supposedly taking place at the level of lexical selection- can in fact be resolved before the involvement of central attentional resources. This suggests that this semantic interference effect possibly reflects a mechanism taking place prior to lexical selection. In a last study, we explored the temporal dynamics of our production system when engaged in the selection of several words within a sequence, using noun phrases. Chronometric results revealed that words are selected strictly sequentially. This dynamics suggests that the way attentional resources are recruited for the selection of an isolated linguistic unit can constrain the way several words are produced in a more natural speaking context.

Este estudo objetivou investigar os componentes posturais reativos em resposta a deslocamentos da base de suporte, perturbando o equilíbrio corporal, em função da realização concomitante de uma tarefa supra-postural manual e incerteza sobre a direção de perturbação. Dezesseis adultos jovens de ambos os sexos (M = 26,3 anos; DP = 2,6) participaram do estudo. A tarefa supra-postural consistiu em equilibrar um cilindro sobre uma bandeja (restrição), cujo desempenho foi verificado por meio do deslocamento angular do cilindro. O desempenho na tarefa postural foi avaliado em função da combinação da incerteza sobre a direção de perturbação postural (anterior ou posterior) e restrição imposta pela tarefa supra-postural, requisitando equilíbrio do cilindro ou manutenção de uma bandeja na orientação horizontal. O desempenho na tarefa postural foi avaliado por meio de análises eletromiográfica de músculos anteriores e posteriores da perna direita e cinemática das principais articulações envolvidas nos ajustes da postura e da tarefa supra-postural. Os resultados mostraram que a tarefa supra-postural com restrição em perturbações previsíveis diminuiu a latência de ativação da musculatura agonista reduziu o deslocamento manual no controle na tarefa supra-postural. A tarefa supra-postural com restrição induziu ajustes diferenciados nas articulações do tornozelo, joelho, quadril e ombro em comparação à condição sem restrição. Os resultados sugerem que a tarefa supra-postural com restrição induziu maior automatização postural para reagir rapidamente à perturbação. Estes resultados indicam que o controle de uma tarefa supra-postural é integrado com a manutenção do controle postural em situações de perturbação do equilíbrio corporal. Além disso, esta integração foi mostrada ser dependente da previsibilidade da direção de perturbação postural. Assim, a principal conclusão deste estudo foi que a restrição imposta pela tarefa supra-postural influencia respostas neurofisiológicas reativas associadas ao controle postural, que são potencializadas pela previsibilidade da perturbação postural / This study aimed to investigate the reactive components of postural adjustments in response to displacements of the basis of support, disturbing body balance, as a function of a concomitant manual execution of a supra-postural task and uncertainty about the perturbation direction. Sixteen young adults of both genders (M = 26,3 years; SD = 2,6) participated in the study. The supra-postural task consisted of equilibrating a cylinder on a tray (constraint), whose performance was assessed through cylinder displacement. The performance on stance was evaluated as a function of a combination of uncertainty of direction of postural perturbation (anterior or posterior) and the constraint imposed by the supra-postural task, requiring equilibrium of the cylinder or maintenance of a tray in a horizontal orientation. Performance on stance was assessed through electromyographic analysis of anterior and posterior muscles of the right leg and kinematics of the main joints involved in postural e supra-postural adjustments. The results showed that the supra-postural task in predictable perturbations decreased the activation latency of agonistic muscles and diminished the manual displacement in the supra-postural task. The constraining supra-postural task induced differential adjustments in the ankle, knee, hip and shoulder in comparison with the condition without constraint. The results suggest that the restrictive supra-postural task induced a more automatic postural control to rapidly react to perturbations, generating more efficient postural adjustments. Thus, the present results suggest that the constraining supra-postural task induced more automatic responses. These results indicate that the control of a supra-postural task is integrated with the maintenance of upright stance in situations of balance perturbation. Moreover, this integration was shown to be dependent on predictability of direction of postural perturbation. So, the main conclusion drawn from our results is that the constraint imposed by the supra-postural task influences reactive neurophysiological responses related to postural control, which are enhanced by postural perturbation predictability

Dementia disorders are difficult to detect in the early stages of the disease. Therefore, it is of importance to develop new methods in early diagnostics. The Uppsala Dalarna Dementia and Gait Study has established a new method in diagnosing early stages of cognitive impairments. The new method Timed-Up-and-Go (TUG) dual-task, combines a gait test with a verbal task. This thesis analyses nine TUG variables for healthy controls and discusses differences between two age groups, subjects younger than 72 years and subjects 72 years or older. Reliability of the new method is the primary focus point and is assessed using Intraclass Correlation Coefficients (ICC) and Bland-Altman plots. Normative reference values for the continuous variables are estimated with the help of bootstrap confidence intervals for the 2.5 and 97.5 percentiles. The results show that the three variables measuring the time to complete the test have good to excellent reliability, while variables that measure combinations of gait and verbal tasks show poor to moderate reliability. The lower reliability for these variables could be explained by them being ratios or differences of other variables. Differences in reliability can be seen between the age groups, where younger subjects have lower reliability partly due to homogeneity. Results show that the reference values of healthy controls are different for the two age groups.

No description available.

La dystonie cervicale (DC) est un trouble du mouvement caractérisé par des postures et des mouvements anormaux du cou et de la tête. Dans la DC, les instabilités posturales ont été associées à une altération des sensations proprioceptives. La présente étude explore l'interaction entre les exigences proprioceptives et attentionnelles du contrôle postural dynamique dans la DC. Des participants sains et atteints de la DC ont effectué une tâche de limite de la stabilité posturale avec et sans vision, ainsi qu'une tâche secondaire cognitive de soustraction. Ces deux tâches ont été effectuées seules (tâche unique) ou simultanément (tâche double). La force de réaction au sol a été recueillie à l'aide d'une plateforme de force AMTI. Les limites fonctionnelles de la stabilité ont été quantifiées comme étant l'excursion maximale du centre de pression (COP) pendant l'inclinaison volontaire du corps dans quatre directions différentes. Les limites de la stabilité des patients DC étaient, en moyenne, plus petites que celles des témoins sains dans toutes les conditions. Cependant, leurs limites antéropostérieures étaient significativement réduites par rapport aux témoins dans la condition de tâche unique sans vision. De plus, les coûts attentionnels de la posture des patients étaient significativement plus élevés que ceux des sujets témoins dans la condition visuelle. Nos résultats soutiennent la théorie selon laquelle l'intégration sensorimotrice et les déficiences proprioceptives affectent le contrôle postural dynamique dans la DC. En outre, nos résultats suggèrent que les patients utilisent diverses stratégies pour s’adapter aux défis posturaux complexes imposés par la vie quotidienne. / Cervical dystonia (CD) is a movement disorder characterized by abnormal postures and movements of the neck and head. Postural instabilities in CD have been associated with impaired proprioceptive processing. The present study used a dual task paradigm to explore the interaction between the proprioceptive and attentional demands of dynamic postural control in CD. Healthy and CD participants performed a postural stability limit task with and without vision as well as a secondary cognitive subtraction task. These two tasks were performed alone (single task) or simultaneously (dual-task). Ground reaction force was collected using an AMTI force platform and center of pressure (COP) displacements were analysed. The functional limits of stability were quantified as the maximum COP excursion during voluntary leaning in four different directions. CD patients achieved, on average, smaller mean postural stability limits compared to healthy controls in all sensory-attentional conditions. However, their anteroposterior stability limits were significantly smaller compared to controls when vision was removed, particularly in the single task condition. Additionally, patients with CD decreased their stability limits relative to healthy controls when concurrently performing the attentional task under the visual condition. Thus, the attentional postural cost of CD patients was greater than the controls. Our results support the theory that sensorimotor integration and proprioceptive impairments affect dynamic postural control in CD. Furthermore, our findings suggest that CD patients use various adaptive strategies to cope with the sensory-attentional challenges imposed by complex postural situations in daily life.

No description available.

<p>Research on backward response compatibility effects (Task 2-to-Task 1 response priming) in the Psychological Refractory Period (PRP) paradigm has suggested that compatibility effects arise from episodic representations of Stimulus-Response (S-R) pairings (Hommel & Eglau, 2002). However, more recent work suggests that these effects are mediated by S-R rules held online in working memory during dual task performance (Ellenbogen & Meiran, 2008). We sought to dissociate these accounts. In Experiment 1, we observed the development of backward response compatibility effects over time in a common PRP task, following varying degrees of prior single task practice of the PRP component tasks. In Experiment 2, we trained participants on a PRP dual task, and then switched Task 2 to one of three different tasks with variable response mapping overlap with the original Task 2, before finally reverting back to the original PRP tasks. Backward response compatibility effects appeared initially, were abolished during the subsequent interference phase, and then reappeared with the original PRP task. Despite equivalent overall performance across conditions suggesting successful task rule instantiation in working memory to guide task performance, backward response compatibility effects were selectively absent in conditions where current S-R rules were mapped in conflict with prior S-R experiences within the experiment. Both experiments provide evidence in favour of an episodic account of backward response compatibility effects, in which prior learning influences subsequent performance in contextually relevant situations. Implications for the understanding of backward response compatibility mechanisms and parallel processing in the PRP paradigm are discussed.</p> / Master of Science (MSc)