Imagética motora é um processo mental que produz modulações na amplitude dos sinas de eletroencefalogramas em progresso. Os padrões presentes nestas modulações podem ser usados para classificar este processo mental, mas a identificação destes padrões não é uma tarefa trivial, porque eles estão presentes em bandas de frequências que são específicas para cada pessoa. Neste trabalho, apresenta-se um novo método para selecionar as bandas de frequência específicas para cada pessoa baseado na arquitetura do método Filter Bank Common Spatial Pattern. Para selecionar as bandas de frequência mais relevantes para cada pessoa, o método proposto aplica uma busca exaustiva para encontrar o melhor subconjunto de bandas de frequência contendo os padrões mais discriminativos dentro de um espaço de busca restrito a um tamanho fixo para este subconjunto. Esse tamanho é determinado usando validação cruzada e o método Sequential Forward Floating Selection. O método proposto foi avaliado usando a base de dados pública 2b da BCI Competition IV, mostrando melhores resultados do que todos os métodos também avaliados nessa base de dados. / Motor imagery is a mental process that when performed, produces modulations in the amplitude of ongoing electroencephalogram signals. These modulations happen following a series of patterns that can be used to classify this mental process, but the detection of those patterns is not a trivial task, because they occur in frequency bands that are specific for each person. In this work, we present a method to select these subject-specific frequency bands based on the arquitecture of the Filter Bank Common Spatial Pattern approach. To select the most relevant frequency bands for each person, our method uses an exhaustive search to find the best subset of frequency bands containing the most discriminative patterns, but with one restriction, the search space is restricted to find a subset with a fixed number of frequency bands. The number is determined using cross-validation and the Sequential Forward Floating Selection method. We demonstrate that, using the data set 2b of the BCI Competition IV, our method is more accurate than current methods evaluated on the same data set.

The use of mobile phones is continually increasing throughout the world, with recent figures showing that there are currently more than 2 billion mobile phone users worldwide. However, despite the recognised benefits of the introduction and widespread use of mobile phone technologies, concerns regarding the potential health effects of exposure to the radiofrequency electromagnetic fields emitted by mobile phone handsets have similarly increased, leading to an increase in demand for scientific research to investigate the possibility of health effects related to the use of mobile phones. An increasing amount of radiofrequency bioeffects research related to mobile phone use has focussed on the possible effects of mobile phone exposure on human brain activity and function, particularly as the absorption of energy in the head and brain region is much higher than in other body regions, which is a direct result from the close proximity of the mobile phone to the head when in normal use. In particular, the use of sleep research has become a more widely used technique for assessing the possible effects of mobile phones on human health and wellbeing, and is particularly useful for providing important information in the establishment of possible radiofrequency bioeffects, especially in the investigation of potential changes in sleep architecture resulting from mobile phone use. A review of the previous literature showed that a number of studies have reported an increase in the electroencephalogram spectral power within the 8 � 14 Hz frequency range in both awake and sleep states following radiofrequency electromagnetic field exposure. In regards to sleep, the enhancements reported have not been entirely consistent, with some early studies failing to find an effect, while more recent studies have reported that the effect differs in terms of particular frequency range. However, in general the previous literature suggests that there is an effect of mobile phone emissions on the sleep electroencephalogram, particularly in the frequency range of sleep spindle activity. In addition to changes in spectral power, changes in other conventional sleep parameters and the production and secretion of melatonin have also been investigated, however, there has been little or no consistency in the findings of previous studies, with the majority of recent studies concluding that there is no influence of mobile phone radiofrequency fields on these parameters of sleep or melatonin. Following a detailed review of the previous research, the current study was developed with the aim to improve on previous methodological and statistical limitations, whilst also being the largest study to investigate mobile phone radiofrequency bioeffects on human sleep. The principle aims were thus to test for the immediate effects of mobile phone radiofrequency electromagnetic fields on human sleep architecture and the secretion of the pineal hormone, melatonin. The experiment included 50 participants who were randomly exposed to active and sham mobile phone exposure conditions (one week apart) for 30 minutes prior to a full night-time sleep episode. The experimental nights employed a randomised exposure schedule using a double-blind crossover design. Standard polysomnography was used to measure subsequent sleep, and in addition, participants were required to provide urine samples immediately following exposure and upon waking in the morning. A full dosimetric assessment of the exposure system was also performed in order to provide sufficient details of the exposure set-up used in the current thesis and to account for the lack of detailed dosimetric data provided in the majority of previous studies. The results of the current study suggest that acute exposure to a mobile phone prior to sleep significantly enhances electroencephalogram spectral power in the sleep spindle frequency range compared to the sham exposure condition. The current results also suggest that this mobile phone-induced enhancement in spectral power is largely transitory and does not linger throughout the night. Furthermore, a reduction in rapid eye movement sleep latency following mobile phone exposure was also found compared to the sham exposure, although interestingly, neither this change in rapid eye movement sleep latency or the enhancement in spectral power following mobile phone exposure, led to changes in the overall quality of sleep. Finally, the results regarding melatonin suggested that, overall, overnight melatonin secretion is unaffected by acute exposure to a mobile phone prior to sleep. In conclusion, the current study has confirmed that a short exposure to the radiofrequency electromagnetic fields emitted by a mobile phone handset immediately prior to sleep is sufficient to induce changes in brain activity in the initial part of sleep. The consequences or functional significance of this effect are currently unknown and it would be premature to draw conclusions about possible health consequences based on the findings of the current study.

Background: Prenatal alcohol exposure causes behavioural, growth and central nervous system deficits in the offspring, termed Fetal Alcohol Spectrum Disorder (FASD). Our lab has previously shown that structured saccadic eye movement tasks probe executive functioning and can be used to measure cognitive dysfunction in children with an FASD, because performance of these tasks reflects the structural integrity of brain areas shown to be vulnerable to prenatal alcohol exposure. Recently developed portable electroencephalographic (EEG) devices record brain activity using a single dry-sensor electrode. Our objectives were: 1) to assess attention and working memory via a delayed memory-guided saccadic eye movement task of varying mnemonic load and 2) to explore the use of a portable single-channel EEG recording device in measuring differences in frontal lobe activity in children with FASD during the performance of this eye movement task. Methods: A total of 18 children with an FASD diagnosis and 19 typically developing control children performed a memory-guided saccadic eye movement task with one, two or three target stimuli. During the task, frontal lobe EEG was recorded using the Neurosky Mindwave Mobile® portable recording device. Results: In the delayed, memory-guided task when two or three target stimuli were required to be held in working memory, children with an FASD performed the task correctly less often than children in the control group. During task performance, children with FASD exhibited a reduction in theta frequency band power, and in alpha frequency band power only at higher mnemonic loads, suggesting that children with FASD recruited more cognitive resources to complete the task. Conclusion: The results of this study suggest that a portable EEG recording device can be used to assist in the recognition of underlying neural mechanisms of executive functioning deficits in children with FASD. Portable devices offer greater user comfort than typical EEG recording equipment as well as flexibility for use outside the laboratory. This could greatly facilitate the study of children with FASD, and other groups who may be less tolerant of typical laboratory environments. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2013-08-14 20:22:10.995

This thesis addresses some theoretical issues generated by the results of recent analysis of EEG time series proving the brain dynamics are driven by abrupt changes making them depart from the ordinary Poisson condition. These changes are renewal, unpredictable and non-ergodic. We refer to them as crucial events. How is it possible that this form of randomness be compatible with the generation of waves, for instance alpha waves, whose observation seems to suggest the opposite view the brain is characterized by surprisingly extended coherence? To shed light into this apparently irretrievable contradiction we propose a model based on a generalized form of Langevin equation under the influence of a periodic stimulus. We assume that there exist two different forms of time, a subjective form compatible with Poisson statistical physical and an objective form that is accessible to experimental observation. The transition from the former to the latter form is determined by the brain dynamics interpreted as emerging from the cooperative interaction among many units that, in the absence of cooperation would generate Poisson fluctuations. We call natural time the brain internal time and we make the assumption that in the natural time representation the time evolution of the EEG variable y(t) is determined by a Langevin equation perturbed by a periodic process that in this time representation is hardly distinguishable from an erratic process. We show that the representation of this random process in the experimental time scale is characterized by a surprisingly extended coherence. We show that this model generates a sequence of damped oscillations with a time behavior that is remarkably similar to that derived from the analysis of real EEG's. The main result of this research work is that the existence of crucial events is not incompatible with the alpha wave coherence. In addition to this important result, we find another result that may help our group, or any other research group working on the analysis of brain's dynamics, to prove or to disprove the existence of crucial events. We study the diffusion process generated by fluctuations emerging from the same model after filtering out the alpha coherence, and we study the recursion to the origin. We study the survival probability of this process, namely the probability that up to a given time no re-crossing of the origin occurs. We find that this is an inverse power law with a power that depends on whether or not crucial events exist.

A preocupação crescente com o desenvolvimento de hábitos saudáveis e uma alimentação adequada vêm promovendo o avanço nas ciências dos alimentos, como também nas relações entre estes e o homem. Nas últimas décadas, a qualidade da análise sensorial tem sido estudada não apenas com base na interação entre o homem e o alimento, mas através da compreensão dos fatores subjetivos e emocionais que influenciam os consumidores. O interesse pelos aspectos emocionais que influenciam essas escolhas amplia os estudos para o terreno das ciências psicológicas, que procuram entender as bases neurocognitivas e analíticas do funcionamento cerebral como motivadores desses processos no homem. O trabalho em neurociência cognitiva tem vislumbrado novos paradigmas, com o desenvolvimento de novas técnicas de observação do cérebro, visando conhecer sua estrutura e função, além de permitir a associação de um comportamento clinico ou experimentalmente observado, não só a um correlato mental presumido, mas também a marcadores específicos da atividade mental observada. Neste sentido, a atividade elétrica cerebral adquirida usando-se o eletroencefalograma (EEG) vem sendo, recentemente, muito usada para monitoramento de eventos cerebrais. Portanto, este trabalho tem como objetivo propor um modelo de análise sensorial que permita avaliar quantitativamente a ação do estímulo gustativo no contexto cognitivo, utilizando o EEG. O experimento foi realizado no laboratório de Física Aplica e Computacional (LAFAC), na Universidade Estadual de São Paulo (USP), Campus Pirassununga, no período de maio/2011 a maio/2012, com 23 voluntários (13 do sexo feminino e 10 do sexo masculino), com idade entre 19 e 24 anos. Foram coletados os sinais de EEG destes voluntários no momento em que experimentavam 27 amostras do sabor doce, sendo nove delas a 0% (água), nove com 0,15% de sacarose (limiar) e nove com 5,0% (concentração máxima). Desta amostragem, foi selecionado um grupo de 7 voluntários (5 do sexo feminino e 2 do sexo masculino) para análise dos dados. Neste estudo constatou-se que quatro voluntários do sexo feminino e um do sexo masculino foram capazes de identificar, através de dados obtidos com o EEG, as diferentes dosagens de sacarose. Os resultados permitem concluir que o modelo de análise sensorial proposta, com a utilização de EEG, para avaliar os estímulos gustativos no contexto cognitivo foi satisfatória e permitiu com a utilização de processamento de sinais digitais e AGR (Análise Adaptativa de Gabor) quantificar com eficiência a percepção dos voluntários as diferentes dosagens apresentadas no experimento. Sugere-se que as diferentes percepções dos voluntários no geral, encontradas no EEG, representam as suas singularidades quanto aos significados atribuídos ao sabor e suas correlações. / The growing concern with the development of healthy habits and a balanced diet allows the progress in Food Science as well as in the relationship between human beings and food. In the last decades the quality of the sensorial analysis has been studied not based only on the interaction between human beings and food but also through the comprehension of subjective and emotional factors that influence customers. The interest in emotional aspects which influence such choices extends the studies to the field of Psychological Science that attempts to understand neurocognitive and analytical bases of brain functioning as motivating elements of those human processes. The work in Cognitive Neuroscience has glimpsed new paradigms due to the development of new techniques about brain observation with the purpose of getting to know its structure and function other than allowing the association of behavior observed experimentally or clinical behavior not considering only a presumed mental correlative but also specific markers of mental activity observed in advance. In that aspect the brain electrical activity acquired through electroencephalogram has been recently used to monitor brain events. Therefore, the aim of this work is to propose a sensorial analysis pattern which allows to evaluate quantitatively the action of taste stimuli within a cognitive context using electroencephalogram. The experiment was carried out in the Laboratory of Applied and Computational Physics (LAFAC) in the University of the State of São Paulo (USP), Pirassununga Campus, from May 2011 to May 2012 with 23 volunteers (13 women and 10 men) aging between 19 and 21 years old. The volunteers\' electroencephalogram signals were collected when they tasted 27 sweet flavored samples, being 9 of them with 0% of sucrose (water), 9 with 0.15% of sucrose (threshold), and 9 with 5% of sucrose (maximum concentration). Seven volunteers were selected from this experiment (5 women and 2 men) whose data was analyzed. In this study was found that four women and one man were able to identify, through the EEG data obtained with the different concentrations of sucrose. The results obtained allowed to conclude that the proposed sensorial analysis pattern using electroencephalogram to evaluate taste stimuli within the cognitive context was satisfactory and allowed, along with the use of digital signals processing and Gabor Adaptive Analysis (AGR), to analyze and to quantify efficiently the volunteers\' perception of different doses presented in the experiment. It is suggested that the different perceptions of volunteers in general, encountered in EEG, representing singularities as to the meanings attributed to taste and their correlations.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18944号 / 工博第3986号 / 新制||工||1614(附属図書館) / 31895 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 松野 文俊, 教授 椹木 哲夫, 教授 富田 直秀 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Multiple sclerosis (MS) is the most common neurological disorder of young adulthood and is often associated with cognitive impairment and emotional dysfunction. Due to the nature of the disease, the cognitive deficits in MS are often variable in their presentation, and consist of deficits in processing speed, attention, working memory, and executive functioning. The purpose of the present study was to explore common methods of documenting MS-related cognitive deficits, to elucidate the relationship between the cognitive deficits seen in MS and physiological markers of cognitive functioning (i.e., quantitative EEG), and to analyze the relationship between cognitive deficits and mood dysfunction in MS. There were 26 participants diagnosed with remitting-relapsing multiple sclerosis and 18 age, sex, and education matched controls. Results of cognitive testing indicated deficits in gross cognitive functioning, language, attention, processing speed, working memory, and executive functioning. A MANOVA encompassing group, task (PASAT and SPT) and load (light and heavy) showed significant group and load effects, but no main effect of task. The MS group performed worse than the controls and both groups performed better on the light load than the heavy load. Post hoc analysis indicated that performance on the PASAT 3 second trial was worse than on the PASAT 2 second trail compared to controls. Given that the PASAT 3 trial is theoretically easier than the PASAT 2 trial and that the PASAT 3 was administered first, the above results likely reflect learning effects. A Repeated Measures ANCOVA encompassing EEG and cognitive data (PASAT and SPT) indicated group-level differences on task performance, and suggested that at rest mean peak alpha frequency (PAF) is associated with performance on the PASAT, but not the SPT. EEG coherence during cognitive tasks was reduced between short-range connections in the theta, alpha, and beta frequency bins and enhanced in a limited number of long-range, anterior to posterior connections in the theta frequency bin in the MS group compared to controls. Finally, the MS participants had significantly more symptoms of depression and anxiety compared to normal controls. A hierarchical multiple regression analysis suggested that cognitive functioning is deleteriously affected by depression and anxiety. Overall, the results of this study substantiate the feasibility of utilizing QEEG as a physiological indicator of cognitive and cortical dysfunction in MS and show the importance of recognizing depression and anxiety and their contributions to cognitive deficits in individuals with MS.

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