O P300 auditivo é um potencial evocado que reflete a atividade neurofisiológica das habilidades cognitivas auditivas de atenção, memória, discriminação e tomada de decisão. A possibilidade de correlacionar aspectos do comportamento auditivo a fenômenos fisiológicos observáveis tem despertado o interesse de profissionais de diversas áreas interessados no estudo das disfunções auditivas. Por ser um procedimento novo, os métodos de análise e interpretação dos resultados ainda não estão padronizados e, portanto, devem ser explorados e discutidos visando maior segurança para aplicação clínica e científica. Este estudo investigou a estabilidade na análise e interpretação do P300 auditivo seguindo um conjunto de regras (critério) pré-determinadas. Para isso, quatro profissionais da área audiológica analisaram, em 2 momentos diferentes, 70 traçados de P300 de crianças e adolescentes saudáveis entre 8 e 18 anos de idade, seguindo as mesmas regras para a identificação das ondas (N1, P2, N2 e P3) e marcação de suas medidas de latência. As medidas de latência da onda P300 foram submetidas a análises qualitativa e quantitativa. A análise qualitativa investigou os tipos de erros cometidos pelo examinador no uso do critério de determinação do P300 (5,9% do total de 560 medidas obtidas). Os erros mais freqüentes no uso do critério foram: não identificar o P300 como a maior onda logo após o complexo N1-P2-N2 e identificar uma “falsa” onda P300. A análise quantitativa investigou a variabilidade da medida da latência do P300 atribuível ao examinador. Os resultados mostraram que não houve diferença significante entre as análises inter e intra-examinador, tendo sido encontradas correlações significantes entre as medidas de latência, indicando boa fidedignidade no teste-reteste e alta concordância entre os examinadores no modo como analisaram os traçados das ondas. O critério usado neste estudo demonstrou ser útil na determinação do P300, podendo ser sugerido com segurança para uso clínico e científico. / The P300 auditory is an evoked potential which reflects the neurophysiological activity of auditory cognitive abilities: attention, memory, discrimination and making decision as well. The possibility of correlation between aspects of auditory behavior and observable physiological phenomena has increased the interest in the study of auditory dysfunctions among professionals of various fields. Due the fact that the P300 is a recent procedure, the methods of its analysis and interpretation have not been standardized yet. Therefore, they must be explored and debated aiming more security for clinical and scientific application. In this study it was investigated the stability in the analysis and interpretation of P300 auditory, according to a pre-determined set of rules. Four audiologists analyzed twice 70 records of P300 of healthy children and adolescents between 8 and 18 years of age, identifying the waves (N1, P2, N2, P3) and their latencies according to the pre-determined set of rule. The P300 latency measurements were submitted to quantitative and qualitative analysis. The qualitative analysis looked into types of errors made by the examiner during the P300 identification (5.9% in a total of 560 measurements). The no-identification of the P300 as the highest wave following the complex N1-P2-N2, likewise the “wrong” identification of P300 wave were the most frequent mistakes. In the quantitative analysis we investigated the variability of the P300 latency measurements attributable to the examiner. The results showed that there were no significant differences between the inter- and intra-examiner analyses. Significant correlations were found between the measurements, showing a good test-retest reliability and high concordance among the examiners in the way they analyzed the wave records. We conclude that the rules used in this study are useful to the identification of the P300 in both clinical and scientific situations.

O presente estudo, através de metodologia sistematizada envolvendo testes eletrodiagnósticos e avaliações dinâmicas da marcha, objetivou analisar e interpretar parâmetros biomecânicos e eletrofisiológicos relacionadas à neuropatia diabética durante a marcha. Analisou e interpretou-se parâmetros temporais, de distribuição da pressão plantar e força reação do solo, adquiridos através de um equipamento específico para tal fim para três grupos experimentais. Analisou-se parâmetros da eletrofisiologia indicadores de respostas somato-sensoriais: cronaxia sensitiva e tolerância à dor em regiões anatomicamente determinadas da superfície plantar. Com tais parâmetros, buscou-se definir os padrões da marcha de indivíduos neuropatas ou não, para intervir de forma mais complexa na descrição e interpretação da doença. Investigou-se relações de dependência entre as variáveis dinâmicas e as eletrofisiológicas como forma de entender outros fatores intervenientes na etiologia das lesões decorrentes, bem como nas alterações compensatórias dinâmicas na marcha desses pacientes, alterações essas que são bilaterais e necessárias para a adaptação devido ao déficit sensorial decorrente da neuropatia. Apesar de não ter sido observada correlação entre estas variáveis, vale ressaltar que esse relacionamento torna-se cada vez mais importante para a compreensão da doença e interpretação de suas diferentes respostas adaptativas na avaliação do comportamento da marcha humana / The purpose of this study is to investigate electrophysiological parameters related to diabetic neuropathy and biomechanical parameters during gait, by systemized methodology, including electrodiagnostic tests and dynamic gait evaluation. We have analysed temporal aspects during stance phase, plantar pressure distribution, and ground reaction forces, acquired by an specific equipment in three experimental groups. We also have studied electrophysiological parameters related to somatic sensorial responses, like sensitive cronaxie and pain tolerance threshold, in some specific anatomical areas of plantar surface. Within these parameters, we searched for defined gait patterns in neuropathic diabetic patients, as well as in diabetic patients without neuropathy, to intervene in a more complex description and interpretation of the disease. We also looked for some relations of dependency between dynamic and electrophysiological variables as a contribution to the better undestanding of the disease ethiology and dynamic compensatory mechanisms in pathological gait. These compensatory mechanisms are usually bilateral, because it is a way of adapting to the sensorial deficit due to the neuropathy. Although there are no observed correlation between these variables, it is good to emphasize that such relationship becomes gradually more important to the understanding of the disease and the interpretation of its different adaptative reactions in human locomotion

In the last decade, traumatic brain injuries (TBIs) and spinal cord injuries (SCIs) has become one of the most scrutinised medical challenges of our time. However, the lower quality of life experienced by the sufferer and the associated socio-economic cost of both TBI and SCI remain a huge burden for society. There is currently no reliable way to evaluate the level of functional damage caused by TBI and SCI related mechanical forces without invasive examination. The types of axonopathy involved in such injuries are the combinations of coupled mechanical-electrophysiological phenomena at multiple length and time scales, extremely challenging to approach by experimental means alone. It is therefore highly desirable to complement experimental studies with computational work to further the understanding of such multiscale problems. This thesis firstly proposes a novel 3D finite element framework coupling mechanics and electrophysiology to model cellular and subcellular phenomena, such as nerve dislocation and membrane damage by micropipette. The former study shows that 1D simulations focussing solely on the stretch component of the axonal damage are unable to capture the same electrophysiological damage that a 3D framework predicts. The latter study shows that local membrane deformation can lead to electrophysiological alterations at the axonal level solely through geometrical effects and without the need to account for ion channel activity alterations. This was demonstrated for micropipette suction in a patch clamp where the consideration of the 3D flow of current was sufficient to alter its electrophysiology, offering an alternative explanation to the damage mechanism hypothesised by published experimental work. At the axonal and tissue scale, previous models have often simplified the modelling of damage by using a single axon model. It is however unclear whether an altered axonal electrophysiology can truly be representative of the compound electrophysiology of multiple axons or fibre. Three different models: axonal, fibre and tissue level models, were evaluated and compared for their ability to model macroscale electrophysiology deficits. The results of the three models suggest that the recovery of compound action potential amplitude post-mechanical stretch can not be straightforwardly scaled from axonal level to fibre level. Furthermore, the electrophysiological recovery may not be solely dependent on mechanical recovery of the tissue. This thesis identified the need for scale specific models in the context of TBI and SCI. In particular, lipid bilayer membrane geometrical distortion following mechanical insult at the subcellular scale and functional tissue alteration at the tissue scale both require a different approach. The models proposed herein successfully identify mechanisms overlooked in previous experimental literature. In order to fully capture experimental behaviour, future models will need to account for other mechanisms such as mechanoporation, reorganisation of paranodal junctions and injury related Calcium ion imbalance.

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Made available in DSpace on 2016-08-03T16:34:28Z (GMT). No. of bitstreams: 1 Henrique Adam Pasquini.pdf: 888682 bytes, checksum: 3ba99f5587a48f9130c806e394f12f25 (MD5) Previous issue date: 2013-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Attention is probably one of the oldest theoretical constructs in Psychology. In the Eastern countries, meditation has been seen as a group of technics that goals to train people to focus attention. This research aims to check its electrophysiological correlates, taking into consideration the long term changes accompanying regular practice of meditation. We have used modern technics of high resolution electroencephalography analyze slow potentials, power in various bands, and event-related band-power. We recorded the EEG using a 128-channel montage, in 31 subjects (17 meditators). We analyzed the type of meditation related to a Zen Buddhist practice of the Soto school, which belongs to the group of mindfulness meditation. The goal of the research was to verify if the power on the beta band would rise. However, not quite what we expected, no significant changes were detected on the beta band. On the other hand, the main finding of this research was that the weekly practice of meditation is associated with a rise in the induced relative theta band power, an increase in the ratio of induced power (theta/beta), and an increase in the ratio of the induced relative band power (theta/beta), which occurred during an adapted meditation task. We also noticed that the practice of meditation was related to a decrease of the alpha peak frequency during the task of focused attention. We discuss the decrease of the alpha peak frequency with respect to the hypothesis of brain efficiency. On the other hand, the increase of the induced relative theta band power and of the ratio of theta/beta induced power bands, during the adapted meditation task, suggests that the plain attention type of meditation is rather related to a deliberate loss of attention, by the permissive distractions of the meditators. / A atenção talvez seja um dos constructos teóricos mais antigos da psicologia. A meditação, por sua vez, tem sido vista no ocidente como um conjunto de técnicas que objetivam o treino da focalização da atenção. Esta pesquisa teve como principal objetivo verificar os correlatos eletrofisiológicos das modificações da atenção em longo prazo em meditadores regulares. Utilizamos as modernas técnicas de eletroencefalografia de alta resolução aplicadas aos potenciais lentos, espectros de potência, potências relacionadas aos eventos. Para obtenção dos registros encefalográficos nós utilizamos uma montagem de 128 canais, em 31 sujeitos (17 meditadores). A meditação estudada compreendeu uma prática zen budista da escola Soto que pertence ao grupo das meditações da atenção plena . A motivação deste estudo foi verificar se a potência na faixa beta se apresentaria aumentada nos meditadores. No entanto, ao contrário do que esperávamos, nenhuma alteração significativa foi encontrada na frequência beta. Em contrapartida, o principal achado do estudo foram correlações entre a frequência da prática semanal da meditação e: o aumento da potência teta induzida relativa, aumento da razão entre potências induzidas (razão teta/beta), e o aumento da razão entre potências induzidas relativas (razão teta/beta) durante nossa tarefa que caracterizou uma meditação adaptada . Verificamos ainda que a prática meditativa apresentou correlação com a diminuição da frequência de pico da faixa alfa durante a tarefa de atenção focada. Discutimos essa diminuição da frequência de pico alfa com respeito a hipóteses de eficiência cerebral. Já o aumento da potência teta induzida relativa, da razão teta/beta das potências induzidas, tomando seus valores absolutos e relativos, bem como o aumento da entre potências induzidas, tomando seus valores relativos, durante a tarefa de observação passiva, sugere que o estado meditativo da atenção plena está muito mais relacionado à permissividade de distrações por parte dos meditadores, com uma diminuição deliberada da atenção.

De nos jours, le domaine biomédical est en pleine croissance avec le développement de dispositifs thérapeutiques innovants, bas coût, pour le diagnostic, le traitement ou la prévention de maladies chroniques ou cardiovasculaires. Ces dernières années ont connu l’émergence des polymères semi-conducteurs, alternative intéressante aux matériaux inorganiques, présentant des propriétés uniques de conduction ionique et électronique. Tout d’abord, j’ai axé mes travaux de recherche sur le développement et l’optimisation d’une encre conductrice à base de PEDOT:PSS, parfait candidat comme matériau, pour la transduction des signaux biologiques en signaux électriques, compatible avec le process jet d’encre, pour la réalisation de dispositifs imprimés. Puis mes travaux se sont orientés vers la conception et l’étude d’électrodes imprimées sur supports papiers, tatous et textiles permettant des enregistrements long termes d’électrocardiogrammes (ECG) ou électromyogrammes (EMG), présentant des performances similaires aux électrodes commerciales, utilisant un système d’acquisition spécifique pour la mesure d’activités électriques de tissus musculaires. Puis dans un second temps, je me suis penchée sur l’impression sur support papier, de transistors organiques électrochimiques (OECTs) fonctionnalisés, afin de permettre la détection d’éléments biologiques ou chimiques comme l’alcool. Ces travaux proposent une nouvelle voie pour la conception de dispositifs innovants biomédicaux à bas couts, imprimés, permettant la personnalisation des produits pouvant être intégrés dans des dispositifs biomédicaux portables ou dans des vêtements « intelligents ». / With the evolution of microelectronics industry and their direct implementation in the biomedical arena, innovative tools and technologies have come to the fore enabling more reliable and cost-effective treatment. In this thesis I focus on the integration of the conducting polymer PEDOT:PSS with printing technologies toward the realization of performant biomedical devices. In the first part, I focus on the optimization of the conducting ink formulation. Following, I emphasize on the fabrication of inkjet printed PEDOT:PSS based biopotential electrodes on a wide variety of substrates (i.e., paper, textiles, tattoo paper) for use in electrophysiological applications such as electrocardiography (ECG) and electromyography (EMG). Printed electrodes on paper and printed wearable electrodes were fabricated and investigated for long-term ECG recordings. Then, conformable printed tattoo electrodes were fabricated to detect the biceps activity during muscle contraction and the conventional wiring was replaced by a simple contact between the tattoo and a similarly ink-jet printed textile electrode.In the last part, I present the potentiality of inkjet printing method for the realization of organic electrochemical transistor (OECTs) as high performing biomedical devices. A disposable breathalyzer comprised of a printed OECT and modified with alcohol dehydrogenase was used for the direct alcohol detection in breath, enabling future integration with wearable devices for real-time health monitoring. Their compatibility with printing technologies allows the realization of low-cost and large area electronic devices, toward next-generation fully integrated smart biomedical devices.

Introduction: major depressive disorder is a common psychiatric disorder associated with high economic cost, severe human suffering, and low remission rates. Imbalanced neurotransmission of the monoaminergic serotonin (5-HT), dopamine (DA) and norepinephrine (NE) systems is implicated in this disorder. However, the etiology underlying this presumed imbalance and the mechanism by which antidepressant strategies restore this imbalance requires further exploration. Accordingly, the present work assessed the effects of depressogenic and antidepressant-like conditions on these systems. Methodology: Electrophysiological extracellular single unit recordings from 5-HT, DA, NE, and hippocampal pyramidal neurons were obtained in adult male chloral hydrate anaesthetized Sprague-Dawley rats. Effects on relevant receptors were characterized using established electrophysiological and/or pharmacological strategies. Prenatal stress was used to model depressogenic-like conditions. The effects on monoamine systems of asenapine and brexpiprazole, two atypical antipsychotics with antidepressant potential, were characterized after acute (brexpiprazole) and sustained administration. These sustained regimens resulted in clinically relevant blood plasma levels. Results: Prenatal stress exposure altered monoamine system activities but did not produce detrimental effects on behavior. Asenapine and brexpiprazole had unique effects on the activities of monoamine systems. Unlike other antipsychotics, both agents did not produce a cessation of the firing of dopamine neurons in the ventral tegmental area, thereby providing novel insights in the role of this system in the treatment of mood disorders. Furthermore, both agents enhanced the tonic activation of postsynaptic 5-HT1A receptors, similarly to the effects of all antidepressant strategies. Conclusion: Prenatal stress altered the activities of 5-HT, NE and DA neurons. Since these central changes were obtained in animals displaying normal behavior, they presumably reflect adaptations to depressogenic-like conditions. The characterization of asenapine and brexpiprazole contributed to a further understanding of their mechanisms of action. Together, these studies provide insight in neural substrates presumably relevant to the antidepressant response.