Abstract The most investigated stages in Brain-Computer Interface are features extraction and task classification. Thus, this work investigates the application of the coherence detector (Magnitude Squared Coherence -MSC) and the Hidden Markov Models (HMM) in the extraction of features and tasks classification, respectively. Features were extracted from electroencephalogram (EEG) in the Delta band (0.1-2 Hz), Alpha band (8-13 Hz) and Beta band (14-30 Hz) using coherence with 5% and 10% significance level (α). The EEG signals were recorded from three healthy subjects during three events: spontaneous EEG, EEG-based motor task and EEG-based motor imagination. We recorded EEG with electrodes placed according to the international 10-20 (first section) and 10-10 systems (second and third sections). HMM observations were obtained by the coherence calculated with 12 trials and the detected frequency range with higher MSC was adopted as a feature for classifier. The hit rate in classification was 72.5 %, 68 % and 65 % for subjects # 1, # 2 and # 3, respectively, using α=5 %. When we used α=10 %, the rates were 72 %, 57.5 % and 67.5 %. Results shown we can extract features from brain activities related to different events by using coherence detector and that HMM is useful in the classification of imaginary movements.

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Aware of the gap that exists between the social rights protected by laws and its full enjoyment, a multidisciplinar team composed of engineers, educators and brazilians students, joined to develop assistive technology products that contribute to the inclusion of people with disabilities, especially those lowincome people. This paper presents a successful experience of this team on the development of valuable technology assistive products with low-tech. Construction procedures that describe how to transform conventional computer peripherals such as mouses and keyboards in custom devices for people with physical disabilities will be presented in details. These procedures were conceived in order to design functional, durable and low-cost products. The group uses the Internet in order to publicly disseminate their knowledges and projects.

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