Submitted by Renato de Macedo Giovanini null (renato81243@aluno.feis.unesp.br) on 2017-09-25T14:52:54Z No. of bitstreams: 1 dissertacao_renato_de_macedo_giovanini_2017_final.pdf: 10453769 bytes, checksum: 7f7e2415a0912fae282affadea2685b8 (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-09-27T20:24:55Z (GMT) No. of bitstreams: 1 giovanini_rm_me_ilha.pdf: 10453769 bytes, checksum: 7f7e2415a0912fae282affadea2685b8 (MD5) / Made available in DSpace on 2017-09-27T20:24:55Z (GMT). No. of bitstreams: 1 giovanini_rm_me_ilha.pdf: 10453769 bytes, checksum: 7f7e2415a0912fae282affadea2685b8 (MD5) Previous issue date: 2017-08-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / There are, nowadays, about 110 million people in the world who live with some type of severe motor disability. Specifically in Brazil, about 2.2% of the population are estimated to live with a condition of difficult locomotion. Aiming to help these people, a vast variety of devices, techniques and services are currently being developed. Among those, one of the most complex and challenging techniques is the study and development of Brain-Computer Interfaces (BCIs). BCIs are systems that allow the user to communicate with the external world controlling devices without the use of muscles or peripheral nerves, using only his decoded brain activity. To achieve this, there is a need to develop robust pattern recognition systems, that must be able to detect the user’s intention through electroencephalography (EEG) signals and activate the corresponding output with reliable accuracy and within the shortest possible processing time. In this work, different EEG signal processing techniques were studied, and it is presented the development of a EEG under visual stimulation (Steady-State Visual Evoked Potentials - SSVEP) pattern recognition system. Using only Open Source tools and Python programming language, modules to manage datasets, reduce noise, extract features and perform classification of EEG signals were developed, and a comparative study of different techniques was performed, using filter banks and Discrete Wavelet Transforms (DWT) as feature extraction approaches, and the classifiers K-Nearest Neighbors, Multilayer Perceptron and Random Forests. Using DWT approach with Random Forest and Multilayer Perceptron classifiers, high accuracy rates up to 92 % were achieved in deeper decomposition levels. Then, the small-size microcomputer Raspberry Pi was used to perform time processing evaluation, obtaining short processing times for every classifiers. This work is a preliminary study of BCIs at the Laboratório de Instrumentação e Engenharia Biomédica, and, in the future, the system here presented may be part of a complete SSVEP-BCI system. / Existem, atualmente, cerca de 110 milhões de pessoas no mundo que vivem com algum tipo de deficiência motora severa. Especificamente no Brasil, é estimado que cerca de 2.2% da população conviva com alguma condição que dificulte a locomoção. Com o intuito de auxiliar tais pessoas, uma grande variedade de dispositivos, técnicas e serviços são atualmente desenvolvidos. Dentre elas, uma das técnicas mais complexas e desafiadoras é o estudo e o desenvolvimento de Interfaces Cérebro-Computador (ICMs). As ICMs são sistemas que permitem ao usuário comunicar-se com o mundo externo, controlando dispositivos sem o uso de músculos ou nervos periféricos, utilizando apenas sua atividade cerebral decodificada. Para alcançar isso, existe a necessidade de desenvolvimento de sistemas robustos de reconhecimento de padrões, que devem ser capazes de detectar as intenções do usuáro através dos sinais de eletroencefalografia (EEG) e ativar a saída correspondente com acurácia confiável e o menor tempo de processamento possível. Nesse trabalho foi realizado um estudo de diferentes técnicas de processamento de sinais de EEG, e o desenvolvimento de um sistema de reconhecimento de padrões de sinais de EEG sob estimulação visual (Potenciais Evocados Visuais de Regime Permanente - PEVRP). Utilizando apenas técnicas de código aberto e a linguagem Python de programação, foram desenvolvidos módulos para realizar o gerenciamento de datasets, redução de ruído, extração de características e classificação de sinais de EEG, e um estudo comparativo de diferentes técnicas foi realizado, utilizando-se bancos de filtros e a Transformada Wavelet Discreta (DWT) como abordagens de extração de características, e os classificadores K-Nearest Neighbors, Perceptron Multicamadas e Random Forests. Utilizando-se a DWT juntamente com Random Forests e Perceptron Multicamadas, altas taxas de acurácia de até 92 % foram obtidas nos níveis mais profundos de decomposição. Então, o computador Raspberry Pi, de pequenas dimensões, foi utilizado para realizar a avaliação do tempo de processamento, obtendo um baixo tempo de processamento para todos os classificadores. Este trabalho é um estudo preliminar em ICMs no Laboratório de Instrumentação e Engenharia Biomédica e, no futuro, pode ser parte de um sistema ICM completo.

O uso de sistemas denominados Brain Computer Interface, ou simplesmente BCI, para controle de dispositivos tem gerado cada vez mais trabalhos de análise de sinais de EEG, principalmente devido ao fato do desenvolvimento tecnológico dos sistemas de processamento de dados, trazendo novas perspectiva de desenvolvimento de equipamentos que auxiliem pessoas com debilidades motoras. Neste trabalho é abordado o comportamento dos classificadores LDA (Discriminante Linear de Fisher) e o classificador Naive Bayes para classificação de movimento de mão direita e mão esquerda a partir da aquisição de sinais eletroencefalográficos. Para análise destes classificadores foram utilizadas como características de entrada a energia de trechos do sinal filtrados por um passa banda com frequências dentro dos ritmos sensório-motor e também foram utilizadas componentes de energia espectral através do periodograma modificado de Welch. Como forma de pré-processamento também é apresentado o filtro espacial Common Spatial Pattern (CSP) de forma a aumentar a atividade discriminativa entre as classes de movimento. Foram obtidas taxas de acerto de até 70% para a base de dados geradas neste trabalho e de até 88% utilizando a base de dados do BCI Competition II, taxas de acertos compatíveis com outros trabalhos na área. / Brain Computer Interface (BCI) systems usage for controlling devices has increasingly generated research on EEG signals analysis, mainly because the technological development of data processing systems has been offering a new perspective on developing equipment to assist people with motor disability. This study aims to examine the behavior of both Fisher's Linear Discriminant (LDA) and Naive Bayes classifiers in determining both the right and left hand movement through electroencephalographic signals. To accomplish this, we considered as input feature the energy of the signal trials filtered by a band pass with sensorimotor rhythm frequencies; spectral power components from the Welch modified periodogram were also used. As a preprocessing form, the Common Spatial Pattern (CSP) filter was used to increase the discriminative activity between classes of movement. The database created from this study reached hit rates of up to 70% while the BCI Competition II reached hit rates up to 88%, which is consistent with the literature.

Os professores, profissionais e estudantes envolvidos na educação a distância, via de regra, não dispõem de uma estrutura e de uma dinâmica para uso eficaz do ferramental tecnológico de software e sistemas disponíveis e assim aproveitar todas as suas potencialidades. O presente estudo tem como objetivo propor estrutura e dinâmica de curso para uso de ambiente virtual de aprendizagem (AVA). Para alcance deste objetivo foi desenvolvida pesquisa, de natureza metodológica, que consistiu na aplicação de conteúdos de enfermagem para oferecimento de curso on-line como uma das ações de workshop internacional para estudantes de graduação em enfermagem do Brasil e de Portugal, onde foram exploradas as principais ferramentas disponíveis no AVA Moodle. Durante o processo de construção e transformação dos conteúdos desenvolvidos em conjunto com professores e equipe técnica, foram registradas algumas etapas distintas, detectados procedimentos específicos a serem realizados por professores, estudantes e equipe técnica. Estes procedimentos, bem como as etapas, estimativas de prazos de realização das atividades, formatos para disponibilização dos conteúdos e os critérios de avaliação utilizados, foram analisados para subsidiar a criação e desenvolvimento do plano estrutural e sua dinâmica. Durante a fase de oferecimento do curso, os conteúdos foram abordados gradativamente, de acordo com cronograma previamente estabelecido, e a equipe docente foi orientada a participar das interações com estudantes e demais membros da equipe. Ao final do evento os estudantes avaliaram o sistema e conteúdos através de instrumento on-line de avaliação de usabilidade baseado em critérios ergonômicos de interface. Para concluir o processo de avaliação, foi executado registro quantitativo de acessos, através de ferramenta de registro de logs e questão dissertativa acerca das ferramentas e formatos utilizados no curso online. A análise dos resultados sinalizou pontos a serem mantidos e aspectos a serem modificados nos conteúdos e formato de utilização das ferramentas. O planejamento apresentou limitações que foram consideradas para o desenvolvimento do produto. Constatou-se também boa receptividade dos estudantes em relação ao formato utilizado. Estes sinalizaram pontos a serem aperfeiçoados. Com base na experiência de oferecimento do curso e na análise dos resultados derivou-se, como produto, uma proposta de estrutura e dinâmica de curso on-line. Este produto é composto por uma proposta de uso de AVA, com mapeamento dos processos de trabalho e diretrizes técnicas de utilização das ferramentas interativas definidas no planejamento e utilizadas para oferecimento do curso. Há necessidade de realização de pesquisas futuras com objetivo de testar o modelo proposto. / Professors, professionals and students involved in distance education often do not have a structure or dynamics available for the efficient use of software or systems in order to take advantage of all their potential as technological tools. This study proposes a course structure and dynamics to be used in a Virtual Learning Environment (VLE). For that, a methodological search was developed, which consisted of applying nursing content to be offered in an online course as one of the activities of an international workshop concerning undergraduate nursing students in Brazil and Portugal, where the main tools available in the AVA Moodle were explored. During the construction and transformation of content developed jointly with professors and the technical team, distinct stages were identified, and specific procedures to be performed by professors, students and the technical team were determined. These procedures as well as the stages, estimated timeframes for performing the activities, format to present content and the evaluation criteria used were analyzed to support the creation and development of the structural plan and its dynamics. Content was gradually addressed throughout the course according to a previously established schedule. The team of professors was prepared to interact with students and remaining team members. At the end of the course, the students evaluated the system and content via an online evaluation usability instrument based on ergonomic criteria evaluating interface. To conclude the evaluation process, a quantitative recording of accesses was performed through a log registration tool and through an essay addressing the tools and formats used in the online course. The results indicated those aspects to be kept and those to be changed in relation to content and the format of tools. Planning presented limitations that were considered in product development. There was good receptivity from students in relation to the format, though they indicated aspects to be improved. The product that resulted from the experience of offering an online course and the analysis of results was a proposal of an online course\'s structure and dynamics. This product is composed of a proposal of AVA use with a map of working processes and technical guidelines concerning the use of interactive tools defined in the planning and that will be used to offer the course. Further research to test the proposed model is needed.

Com o aumento da acessibilidade à tecnologia, programas de reabilitação para pessoas com paralisia cerebral (PC) usam cada vez mais ambientes de realidade virtual para melhorar o desempenho e a prática motora. Sendo assim, é importante verificar se a melhoria de desempenho em uma tarefa praticada em ambiente com característica virtual pode ser observado quando esta mesma tarefa for praticada em ambiente com característica real. Para analisar esta questão, foram avaliadas 64 pessoas, das quais 32 com PC e 32 com desenvolvimento típico (DT), ambos os grupos submetidos a duas tarefas de timing coincidente: a) tarefa em ambiente com característica real (com contato físico), na qual era necessário \"interceptar\" um objeto virtual que se movimentava na tela do computador, e no momento em que este objeto chegasse ao ponto de interceptação as pessoas deveriam pressionar a barra de espaço no teclado; b) tarefa em ambiente com característica virtual (sem contato físico), na qual as pessoas foram instruídas a \"interceptar\" o objeto virtual, fazendo um movimento com a mão sob uma webcam (ambiente virtual). Os resultados indicaram que as pessoas com PC apresentaram menor acurácia do que as pessoas com desenvolvimento típico, no entanto melhoraram seu desempenho durante a tarefa. É importante ressaltar que os resultados também mostraram que depois de praticar a tarefa sem contato físico, o desempenho das pessoas com PC na tarefa com contato físico manteve-se pior do que o desempenho de pessoas que praticaram a primeira tarefa com contato físico. Podemos concluir que a utilização de ambientes virtuais para reabilitação motora em pessoas com PC deve ser considerada com cautela, já que o ambiente em que a tarefa é realizada apresenta implicações importantes na aprendizagem desta população / With the growing accessibility of computer-assisted technology, rehabilitation programs for individuals with cerebral palsy (CP) increasingly use virtual reality environments to enhance motor practice. Thus, it is important to examine whether performance improvements in the virtual environment generalize to the natural environment. To examine this issue, we had 64 individuals, 32 of which were individuals with CP and 32 typically developing individuals, practice two coincidence-timing tasks. In the more tangible button-press task, the individuals were required to \'intercept\' a falling virtual object at the moment it reached the interception point by pressing a key. In the more abstract, less tangible task, they were instructed to \'intercept\' the virtual object by making a hand movement in a virtual environment. The results showed that individuals with CP timed less accurate than typically developing individuals, especially for the more abstract task in the virtual environment. The individuals with CP did -as did their typically developing peers- improve coincidence timing with practice on both tasks. Importantly, however, these improvements were specific to the practice environment, there was no transfer of learning. It is concluded that the implementation of virtual environments for motor rehabilitation in individuals with CP should not be taken for granted but needs to be considered carefully

O uso de sistemas denominados Brain Computer Interface, ou simplesmente BCI, para controle de dispositivos tem gerado cada vez mais trabalhos de análise de sinais de EEG, principalmente devido ao fato do desenvolvimento tecnológico dos sistemas de processamento de dados, trazendo novas perspectiva de desenvolvimento de equipamentos que auxiliem pessoas com debilidades motoras. Neste trabalho é abordado o comportamento dos classificadores LDA (Discriminante Linear de Fisher) e o classificador Naive Bayes para classificação de movimento de mão direita e mão esquerda a partir da aquisição de sinais eletroencefalográficos. Para análise destes classificadores foram utilizadas como características de entrada a energia de trechos do sinal filtrados por um passa banda com frequências dentro dos ritmos sensório-motor e também foram utilizadas componentes de energia espectral através do periodograma modificado de Welch. Como forma de pré-processamento também é apresentado o filtro espacial Common Spatial Pattern (CSP) de forma a aumentar a atividade discriminativa entre as classes de movimento. Foram obtidas taxas de acerto de até 70% para a base de dados geradas neste trabalho e de até 88% utilizando a base de dados do BCI Competition II, taxas de acertos compatíveis com outros trabalhos na área. / Brain Computer Interface (BCI) systems usage for controlling devices has increasingly generated research on EEG signals analysis, mainly because the technological development of data processing systems has been offering a new perspective on developing equipment to assist people with motor disability. This study aims to examine the behavior of both Fisher's Linear Discriminant (LDA) and Naive Bayes classifiers in determining both the right and left hand movement through electroencephalographic signals. To accomplish this, we considered as input feature the energy of the signal trials filtered by a band pass with sensorimotor rhythm frequencies; spectral power components from the Welch modified periodogram were also used. As a preprocessing form, the Common Spatial Pattern (CSP) filter was used to increase the discriminative activity between classes of movement. The database created from this study reached hit rates of up to 70% while the BCI Competition II reached hit rates up to 88%, which is consistent with the literature.

As pessoas com deficiência compreendem uma parcela da população as quais as formas de planejamento dos espaços urbanos causam impacto direto em sua qualidade de vida, sendo a incapacidade visual a mais abrangente entre as deficiências, acometendo mais de 35 milhões de pessoas no Brasil. Nas últimas décadas, as normas e leis brasileiras de promoção da acessibilidade buscam criar condições para que as pessoas com deficiências possam ter uma vida social e econômica mais ativa, por meio do uso dos preceitos do design universal nos projetos de acessibilidade para espaços públicos e meios de transporte. No entanto, definir regulamentos e normas tem se mostrado insuficiente, pois a simples padronização de recursos físicos, como pisos táteis, não garantem a autonomia para o deslocamento das pessoas com deficiência visual. Paralelo às adequações dos espaços públicos para a acessibilidade, algumas tecnologias eletrônicas têm sido desenvolvidas de forma efetiva para o design universal, dentre elas as atuais formas de audiodescrição de programas de TV, cinemas e teatros, assim como o desenvolvimento de tecnologias de voz sintetizada para quepessoas com deficiência visual possam fazer uso dos portáteis smartphones. Neste estudo, foram realizadas pesquisas bibliográficas e experimentos em ambientes controlados e ambientes públicos, utilizando-se de técnicas de pesquisa qualitativa para o levantamento, registro e análise de informações, por meio da observação de voluntários com deficiência visual, enquanto utilizavam um modelo primordial de equipamento com voz digital para orientá-los em três ambientes públicos na cidade de São Paulo, compreendendo uma movimentada estação de metrô, uma calçada a céu aberto e uma instituição pública de cultura. Os experimentos demonstraram que os voluntários com deficiência visual podem utilizar um formato adequado de audiodescrição para a orientação e mobilidade, contanto que sejam consideradas peculiaridades que relacionem a velocidade de marcha de pessoas com deficiência visual com os processos cognitivos pertinentes à audição e à percepção ambiental. Por consequência, esta pesquisa oferece princípios para o design de audionavegação, por meio de readequações na audiodescrição para abranger os conceitos de orientação e mobilidade, de modo a possibilitar sua aplicação em projetos de interfaces eletrônicas portáteis com voz sintetizada para orientar pessoas com deficiência visual, buscando assim um incrementando na autonomia dessas pessoas para seu wayfinding em ambientes públicos e transportes de massa. / The people with disabilities comprise a portion of the population whose forms of planning in urban spaces have a direct impact on their quality of life, with visual impairment being the most comprehensive among disabilities, affecting more than35 million individuals in Brazil. In the last decades, the Brazilian norms and laws to promote accessibility seek to create conditions for people with disabilities to have a more active social and economic life, through the use of universal design precepts in the projects of accessibility for public spaces and mass transports. However, setting regulations and norms has proved insufficient, since the simple standardization of physical resources, such as tactile floors, do not guarantee autonomy for the displacement of visually impaired people. Parallel to the adaptations of public spaces for accessibility, some electronic technologies have been effectively developed for the universal design, amongst them the present forms of audiodescription of TV programs, cinemas and theaters, as well as the development of synthesized voice technologies so that people with visual disabilities can make use of portable smartphones. In this study, in addition to relevant bibliographical research, practical experiments were carried out in controlled and public environments, applying qualitative research techniques for the collection, recording and analysis of information through the observation of volunteers with visual impairment, using a primordial model of equipment with digital voice technology to guide them in three public spaces in the city of São Paulo, comprising a busy subway station, a sidewalk and a public cultural institution. The experiments have shown that visually impaired volunteers can use an appropriate format of audiodescription for orientation and mobility, as long as they are considered peculiarities that relate the visually impaired people walking speed to cognitive processes relevant to hearing and for environmental perception. As a result, this research offers principles for the audionavigation design, through adjustments in audiodescription to include the orientation and mobility concepts, enabling its application in projects of portable electronic interfaces with synthesized voice to guide visually impaired people, seeking an increase in wayfinding autonomy for these people when in public environments and mass transports.

A pesquisa explora a intersecção entre o design de informação e os estudos acerca do fenômeno urbano, considerando o avanço recente das tecnologias voltadas à representação e as possibilidades que trazem à comunicação visual. É proposta uma introdução ao tema da cidade, abordada tanto de uma perspectiva macro, que busca embasamento nas ciências, quanto do ponto de vista da experiência urbana de seus usuários. Em seguida, são investigadas as possibilidades do design de informação nesse contexto, por meio de uma revisão bibliográfica da teoria relacionada ao tema e da análise de projetos e iniciativas que buscam aproximar, por meio do design e do uso de ambientes virtuais, conjuntos de dados e informações da cognição humana. Com relação às tecnologias, são investigadas ferramentas de representação da informação urbana, envolvendo visualização de dados, interação humano-computador e navegação por ambientes tridimensionais. Em um paralelo com a arquitetura, são observadas formas como a informação tem sido espacializada em ambientes físicos e virtuais. Por fim, o trabalho propõe investigações práticas, de modo a explorar particularidades de algumas das ferramentas disponíveis, e pondera sobre a atuação do designer na representação da informação urbana à luz das questões estudadas. / This research explores the intersection between information design and studies on urban phenomena, considering the recent developments in technologies of representation and possibilities that they bring to visual comunication. An introduction to the theme of the city is proposed, viewed both from a macro perspective, that seeks grounding in science, and from the perspective of the user experience. Then, are investigated the possibilities of information design in this context, trough a literature review of the theme and analysis of information design projects that seek to approach urban issues and human cognition. With regard to digital technologies, the representation of urban information evolving automatized data visualization, human-computer interaction and navigation in 3D environments are investigated. In a parallel with architecture, ways in which information has been spatialized in physical and virtual environments are observed. Lastly, the research proposes a practical investigation, to explore particularities of some available tools and to consider the role of designers on representation of urban information, taking into account the studied issues.

Les interfaces cerveau-machine (ICM) permettent de contrôler une machine directement à partir de l'activité cérébrale. Le P300-Speller, en particulier, pourrait offrir à des patients complètement paralysés, la possibilité de communiquer sans l'aide de la parole ou du geste. Nous avons cherché à améliorer cette communication en étudiant la coadaptation entre cerveau et machine. Nous avons d'abord montré que l'adaptation d'un utilisateur peut être partiellement perçue, en temps-réel, à travers les modulations de sa réponse électrophysiologique aux feedbacks de la machine. Nous avons ensuite proposé, testé et évalué les effets sur l'utilisateur de plusieurs approches permettant d'améliorer l'interaction, notamment : la correction automatique des erreurs, grâce à la reconnaissance en temps-réel des réponses aux feedbacks ; une stimulation dynamique permettant de diminuer le risque d'erreur tout en réduisant l'inconfort lié aux stimulations ; un processus automatique de décision adaptative, en fonction de l'état de vigilance du sujet. Nos résultats montrent la présence de réponses aux feedbacks spécifiques des erreurs et modulées par l'attention ainsi que par la surprise du sujet face au résultat de l'interaction. Par ailleurs, si l'efficacité de la correction automatique est variable d'un sujet à l'autre, le nouveau mode de stimulation comme la décision adaptative apparaissent comme très avantageux et leur utilisation a un effet positif sur la motivation. Dans la perspective d'études cliniques pour évaluer l'utilité des ICM pour la communication, ces travaux soulignent et quantifient l'intérêt de développer des interfaces capables de s'adapter à chaque utilisateur / Brain-computer interfaces (BCI) aim at enabling the brain to directly control an artificial device. In particular, the P300-Speller could offer patients who cannot speak and neither move, to communicate again. This work consisted in improving this communication by implementing and studying a coadaptation between the brain and the machine. First, on the user side, we showed that adaptation is reflected in real-time by modulations of the electrophysiological responses to the feedbacks from the machine. Then, on the computer side, we proposed, tested and evaluated the effect on the user, of several approaches that endow the machine with adaptive behavior, namely: Automatic correction of errors, based on real-time recognition of feedback responses; Dynamic stimulation to increase spelling accuracy as well as to reduce the discomfort associated with the traditional row/column stimulation paradigm; Adaptive decision making for optimal stopping, depending on the attentional state of the user. Our results show the presence of feedback responses which are error specific and modulated by attention as well as user's surprise with respect to the outcome of the interaction. Besides, while the interest of automatic correction is highly subject-dependant, the new stimulation mode and the adaptive decision method proved clearly beneficial and their use had a significant positive impact on subject's motivation. In the perspective of clinical studies to assess the usefulness of ICM for communication, this work highlights and quantifies the importance of developing adaptive interfaces that are tailored to each every individual

Electronic networks services have become essential tools for the academic community. One of the services provided has been academic electronic bulletin boards (EBBs), and the use of EBBs has increased dramatically during the last decade. One question concerns the possible application of EBBs as a means both for communication and for remote training. A series of experiments were conducted during 1991, 1992, and 1993 with the aim of examining the use of EBBs for these purposes. The first experiment was carried out to investigate whether users experience problems in using EBBs. The next extended this to see how students evaluated EBBs for communication and training purposes. The main focus of the work was BUBL. After this second experiment, modifications were made to the BUBL data and a further experiment was carried out. A different group of students looked at the modified material, and also compared it with US data using different software. The fourth experiment compared the usability of a menu-based interface (dBase III +) and a hypertext interface (HyperCard) from a student's viewpoint. It was followed by an investigation of icons to find out how well different icons could be recognised and the possibility of using them for language-independent instructions. Finally, the characteristics and problems of GULFNET users were examined. The evaluation has demonstrated the general acceptability of EBBs and their likely value for training purposes. This leads to a discussion of how an EBB might best be developed for use in communication and training on GULFNET.

A Brain-Computer Interface (BCI) is a system to communicate with external world through the brain activity. The brain activity is measured by Electro-Encephalography (EEG) and then processed by a BCI system. EEG source reconstruction could be a way to improve the accuracy of EEG classification in EEGbased brain–computer interface (BCI). In this thesis BCI methods were applied on derived sources which by their EEG enhancement it became possible to obtain a more accurate EEG detection and brought a new application to BCI technology that are recognition of writing letters imagery from brain waves. The BCI system enables people to write and type letters by their brain activity (EEG). To this end, first part of the thesis is dedicated to EEG source reconstruction techniques to select the most optimal EEG channels for task classification purposes. Due to this reason the changes in EEG signal power from rest state to motor imagery task was used, to find the location of an active single equivalent dipole. Implementing an inverse problem solution on the power changes by Multiple Sparse Priors (MSP) method generated a scalp map where its fitting showed the localization of EEG electrodes. Having the optimized locations the secondary objective was to choose the most optimal EEG features and rhythm for an efficient classification. This became possible by feature ranking, 1- Nearest Neighbor leave-one-out. The feature vectors were computed by applying the combined methods of multitaper method, Pwelch. The features were classified by several methods of Normal densities based quadratic classifier (qdc), k-nearest neighbor classifier (knn), Mixture of Gaussians classification and Train neural network classifier using back-propagation. Results show that the selected features and classifiers are able to recognize the imagination of writing alphabet with the high accuracy. / BCI controls external devices and interacts with the environment by brain signals. Measured EEG signals over the motor cortex exhibit changes in power related to the movements or imaginations which are executed in motor tasks [1]. These changes declare increase or decrease of power in the alpha (8Hz-13Hz), and beta (13Hz-28Hz) frequency bands from resting state to motor imagery task that known as event related synchronization (in case of power increasing) and desynchronization (in case of power decreasing) [2]. The necessity to communicate with the external world for locked-in state (LIS) patients (a paralyzed patient who only communicates with eyes), made doctors and engineers motivated to develop a BCI technology for typing letters through brain commands. Many researches have been done around this area to ascertain the dream of typing for handicapped. In the brain some regions of the cerebral cortex (motor cortex) are involved in the planning, control, and execution of voluntary movements. Electroencephalography (EEG) signals are electrical potential generated by the nerve cells in the cerebral cortex. In order to execute motoric tasks, the EEG signals are appeared over the motor cortex [1]. The measured brain response to a stimulus is called eventrelated potential (ERP). P300-event related potential (ERP) is an evoked neuron response to an external auditory or visual stimulus that is detectable in scalp-recorded EEG (The P300 is evoked potential which occurs across the parieto-central on the skull 300 ms after applying the stimulus). Farwell and Donchin have proven in a P300-based BCI speller [3] that P300 response is a reliable signal for controlling a BCI system. They described the P300 speller, in which alphanumeric characters are represented in a matrix grid of six-by-six matrix. The user should focus on one of the 36 character cells while each row and column of the grid is intensified randomly and sequentially. The P300, observed in EEG signals, is created by the intersection of the target row and column which causes detection of the target stimuli with a probability of 1/6 (in case of high accuracy of flashing operation). Also when the target stimulus is rarely presented in the random sequence of stimuli causes a neural reaction to unpredictable but recognizable event and a P300 response is evoked [3]. Generally when the subject is involved with the task to recognize the targets, the P300 wave happens and the signal amplitude varies with the unlikelihood of the targets. Its dormancy changes with the difficulty of recognizing the target stimulus from the standard stimuli [3].The attended character of the matrix can be extracted by proper feature extraction and classification of P300. A plenty of procedures for feature extraction and classification have been applied to improve the performance of originally reported speller [3], such as stepwise linear discriminate analysis (SWLDA) [4, 5], wavelets [1], support vector machines [6, 7, 8] and matched filtering [9]. Till now, BCI-related P300 research has mostly considered on signals from standard P300 scalp locations. While in [10, 11, 12, 13, 14, 15, 16] it has been proven that the use of additional locations, especially posterior sites, may improve classification accuracy, but it has not been addressed to particular offline and online studies. Recently, auditory version improvement of the visual P300 speller allows locked in patients who have problem in the visual system to use the P300 speller system by relating two numbers to each letter which indicate the row and column of letter position [17]. Now a new technology is needed which can substitute a keyboard with no alphabet menu. The technology will be handy for blind people and useful for healthy persons who need to work hands free with their computer or mobile. The aim of this thesis is to improve EEG detection through source localization for a new BCI application to type with EEG signals without using alphabet menu. / +98-9359576229