Thesis (M. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 94-102). Also available in electronic format on the Internet.

Thesis (Ph.D)--Computing, Georgia Institute of Technology, 2010. / Committee Member: Alexander Gray; Committee Member: Charles Lee Isbell Jr.; Committee Member: Melody Moore Jackson; Committee Member: Paul M. Corballis; Committee Member: Thad Starner. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M. Phil.)--University of Hong Kong, 2006.

Event related potentials (ERPs) are obtained from noninvasive electroencephalograms (EEG) which measure neuronal activity of brain on the scalp. However, conventional ERPs derived by averaging of single EEG trials have strong latency variability and are smeared, resulting in blurred scalp topography, especially in late components of ERP. The smearing problem had been addressed by reconstructing ERPs after latency correction with a new EEG analysis method Residue Iteration Decompo¬sition (RIDE), which was demonstrated in a face priming paradigm to improve distinctness in scalp topography (Ouyang et al., 2011). This thesis aims to (1) extend the benefits of RIDE to neural source space by localizing the neural generators of ERPs, thereby developing an integrated RIDE framework for improvement in source localization and causal modeling of effective source networks, and (2) apply the framework to the face priming paradigm for famous faces, to explore the dynamics of face processing and priming. We localized sources through brain electrical source analysis for both conventional ERP and RIDE derived ERPs (RERPs). RERPs allowed localization of an additional motor execution source (Premotor Cortex, PMC), apart from 5 other common sources, of which 2 (Occipital Lobe, OL; Fusiform Gyrus, FG) were obtained from early activity (< 250 ms) and 3 (Mediotemporal lobe, MTL; Prefrontal Cortex, PFC; Anterior Temporal Lobe, ATL) from late activities (> 250 ms) of RERPs respectively. Priming effects, i.e., the difference between primed famous (PF) and unprimed famous (UF) face conditions in source waveforms (SWFs), were extended and enhanced in RERPs, especially for late sources. The priming effects revealed (1) the role of sources in each hemisphere that play in perception, memory and execution, (2) parallel processing of information in sources, (3) early processing in the right hemisphere, and (4) predominance of the right hemisphere in face recognition. Results confirmed SWFs of RERPs as better choice for the dynamic causal model (DCM). Two candidate DCM models, forward (F) and forward-backward (FB) were outlined on each hemisphere with SWFs from PF and UF conditions of RERP data. Priming has tendency to facilitate the FB model in the left hemisphere. On the other hand, independent of model preference, priming strengthened a bidirectional connection between FG and PFC in both hemispheres; this indicates a strong role of FG in structural representation and of PFCs in controlling decisions about face familiarity. Priming modulates the pathway FGMTLPFC differently in the two hemispheres, strengthening the involvement of MTL in the left hemisphere and weakening in the right hemisphere. This indicates proficiency of the left and right MTL in processing different aspects of facial information. Further, a backward connection ATLPFC in the left hemisphere was found to be functionally relevant for both conditions in speeding up response time in individual subjects, reinforcing the role of PFC in executive functioning and ATL in naming of famous faces. Thus, an integrated framework of source localization and DCM with RERPs allows a novel, comprehensive understanding of time resolved dynamics in face recognition and priming, thereby piloting prospects of its application to other experimental paradigms.

Objective: This dissertation was undertaken to explore the clinical utility of physiological and behavioural metrics of neurocognitive adaptability in the screening of older adults for possible early signs of pathological cognitive aging. Methods: This was an intensive, multi-method study of 44 healthy (non-demented) Victoria-area older adults (ages 65 to 80 years). Study 1 examined timescale-specific differences in resting electroencephalographic (EEG) adaptability as a function of subtle cognitive decline. Study 2 described differences in retest practice effect -- within and across a burst of 4 to 6 occasions of computerized cognitive testing -- with respect to individual variation in estimated premorbid function and self-reported conscientiousness. Study 3 considered whether practice effects from Study 2 were related to individual differences in the resting EEG marker derived in Study 1, above and beyond the differences due to premorbid function and conscientiousness. Results: Study 1 revealed that older adults with neuropsychological performance indicators of subtle cognitive decline also showed subtle, timescale-specific differences in resting EEG adaptability. Study 2 illustrated the differentiable effects of individual differences in estimated premorbid function and conscientiousness on within- and across-occasion improvement on a computerized attention-shifting (switch) task. Study 3 demonstrated the unique promotional effects exerted by conscientiousness and resting EEG adaptability on the rate of across-occasion improvement in cognitive performance. Conclusions: Useful yet under-used tools for detecting early signs of neurocognitive decline include rigorous, standardized neuropsychological diagnostic criteria, the magnitude of practice-related improvement in cognitive performance, and characteristics of the brain's resting electrical activity. Future multi-method, ecologically-situated studies are needed to establish standardized protocol that can be used to screen growing worldwide numbers of older adults for losses in neurocognitive adaptability that may herald the earliest stages of pathological neurocognitive aging. / Graduate

At least 20% of the US population is estimated to be bilingual, and there is wide popular and academic interest in the neurocognitive consequences of bilingualism. A controversial body of literature points to “bilingual advantages” in executive function (EF) skills involving attention, inhibitory control, and cognitive flexibility. However, while bilingual advantages are thought to be a result of neuroplasticity, we do not currently understand the specific neural mechanisms shaped in childhood. Further, studies have failed to account for the distinction between “cool,” more purely cognitive, and “hot,” more affective and motivationally relevant EF systems. Lastly, the study of bilingual EF development has been sparse in preschool children, when EF skills are most rapidly developing. The present research compared behavioral, neurocognitive, and demographic correlates of cool (cognitive) and hot (affective) EF, in healthy monolingual and bilingual children with at least 20% exposure to a second language. In Study 1, I examined whether 3.5. - 4.5 year old bilinguals show better and faster conflict inhibition and cognitive flexibility, and neural differences in inhibition, monitoring, and error-processing, in cool and hot contexts. Results showed faster cool inhibition and faster hot cognitive flexibility in bilinguals, accompanied by neural differences in cool error-processing. In Study 2, I examined whether 6-8 year old bilinguals show better and faster interference control in cool and hot tasks, and neural difference in inhibition, monitoring, error-processing, and response preparation. Results showed no performance or neural differences between groups. In Study 3, I examined whether 6-8 year old bilinguals show better and faster flexible switching in linguistic and non-linguistic contexts, and better word-object mapping in an unfamiliar language. Results showed no performance differences between groups. In addition to the behavioral and neural findings, all three studies revealed group differences in demographic and cognitive correlates of EF. Together, results suggest that bilingual advantages may be most relevant in preschoolers, susceptible to motivational context, supported by error-awareness mechanisms, and unrelated to motor processing. Future studies of error-processing and response-preparation mechanisms can shed light on how bilingualism shapes brain function, and can elucidate group differences in the behind-the-scenes of inhibitory and switching processes.

Made available in DSpace on 2015-07-22T20:50:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Introdução: A epilepsia é o distúrbio neurológico crônico mais comum no mundo. Além do tratamento medicamentoso e cirúrgico, tratamentos complementares têm sido estudados, como a prática regular de exercício físico. Apesar de importantes avanços no entendimento dos efeitos do exercício físico em modelos experimentais de epilepsia, pouco ainda se sabe sobre as respostas fisiológicas ao exercício em humanos, provavelmente pelas limitações práticas encontradas na realização de pesquisas em pessoas com epilepsia. Considerando que pessoas com epilepsia, na sua grande maioria, são sedentárias, o condicionamento cardiorrespiratório dessas pessoas pode estar prejudicado quando comparado com pares saudáveis, da mesma idade, sexo e status de treinamento. Adicionalmente, a avaliação das respostas eletrencefalográficas durante o esforço físico intenso em pessoas com epilepsia tem sido pouco explorada. A análise do comportamento das variáveis fisiológicas e eletrencefalográficas em repouso, durante a realização do teste de exercício cardiorrespiratório (TECR) e na recuperação após o teste pode revelar particularidades nestas pessoas, como já ocorreu em outros distúrbios, e tal constatação pode ser de grande utilidade para processos terapêuticos que utilizem o exercício físico. Objetivo: Avaliar as respostas fisiológicas e eletrencefalográficas, no estado de repouso, durante a realização do TECR e na recuperação após o TECR de pessoas com epilepsia, comparando-as com as de pessoas saudáveis. Casuística e Métodos: Foram avaliadas 40 pessoas de ambos os sexos pareadas pelo gênero, massa corporal, idade e status de treinamento, das quais 20 pertenceram ao grupo epilepsia (GE) e 20 ao grupo controle (GC). As seguintes avaliações e medidas foram conduzidas: nível de atividade física habitual, qualidade de vida, TECR, eletroencefalograma (EEG) e variabilidade da frequência cardíaca. Resultados: O nível de atividade física habitual realizada no lazer foi 14,4% maior no GC quando comparado ao GE. Na avaliação da qualidade de vida, foram encontrados valores significativamentes menores no GE no bem estar emocional (18%), na função cognitiva (31,5%) e no estado global de saúde (27%) quando comparado ao GC. Com respeito às respostas fisiológicas obtidas a partir do TECR apenas os valores de V . O2pico (16,2%), V . O2 do limiar anaeróbio (18,5%) e V . O2 do ponto de compensação respiratória (16%), foram significativamente inferiores no GE em comparação ao GC. Estes achados podem estar relacionados com o menor nível de atividade física realizada no lazer pelo GE. Embora a diferença não tenha sido estatisticamente significante, a análise do EEG mostrou que o número de descargas epileptiformes do GE diminuiu do estado repouso para o esforço físico (82%) e do repouso para a recuperação (74%). Além do mais, após a interrupção do TECR o número de descargas epileptiformes voltou a aumentar em aproximadamente 30%. Os índices que avaliam a variabilidade da frequência cardíaca, tanto no domínio do tempo quanto no da frequência, não se mostraram alterados entre os grupos no estado de repouso, na realização do TECR e recuperação após o teste. Conclusões: Pessoas com epilepsia apresentam menor aptidão aeróbia com relação à população geral. Tal fato parece estar associado com hábitos sedentários. Por outro lado, a prática de exercícios intensos parece ter um efeito benéfico para pessoas com epilepsia, caracterizado por uma redução das descargas epileptiformes nas fases de exercício e de recuperação, comparado com a condição de repouso. Concluindo, nossos achados demonstram que não há peculiaridades nas respostas fisiológicas durante o exercício incremental que requeiram um diferencial de cuidados na avaliação da aptidão física aeróbia destas pessoas. / Introduction: Epilepsy is the most common chronic neurological disorder in the world. In addition to drug treatment and surgery, complementary treatments have been studied, such as physical exercise. Despite important advances in understanding the effects of an exercise program in experimental models of epilepsy, little is known about these effects in humans, probably by the practical limitations encountered in conducting research in people with epilepsy. Whereas people with epilepsy are mostly sedentary, cardiorespiratory fitness of these people may be impaired when compared to healthy pairs of the same age, gender and status of training. Additionally, the evaluation of electroencephalographic responses by electroencephalogram (EEG) during intense physical effort in persons with epilepsy has been little explored. The analysis of behavior of physiological variables and EEG at rest, during cardiopulmonary exercise test (CPET) and in the recovery period may reveal peculiarities in people with epilepsy that may be useful in therapeutic procedures. Objetives: To evaluate the physiological responses and EEG in the resting state, during the CPET and in the recovery after CPET of people with epilepsy, comparing them with those of healthy people. Casuistic e Methods: We evaluated 40 persons of both sexes matched by gender, body mass, age and status of training, of which 20 composed the epilepsy group (EG) and 20 the control group (CG). The following assessments and measurements were conducted: level of habitual physical activity, quality of life, CPET, EEG and heart rate variability. Results: The level of physical activity performed during leisure time was 14.4% higher in CG compared to EG. In the evaluation of quality of life, were found values significantly lowers in the EG for the emotional well-being (18%), cognitive function (31.5%) and global health status (27%) compared to CG. With respect to physiological responses obtained from CPET only the values of V . O2peak (16.2%), V . O2 anaerobic threshold (18.5%) and V . O2 from the point of respiratory compensation (16%) were significantly lowers in EG compared to the CG. These findings may be related to lower levels of physical activity performed during leisure time at the EG. Although the EEG findings were not statistically significant, it was observed a reduced number of epileptiform discharges in the EG from resting state to physical effort (82%) and from resting state to the recovery period (74%). Moreover, after discontinuation of CPET the number of epileptiform discharges increased again by approximately 30%. The indexes which measure the heart rate variability, in the time and frequency domains, were not different between the groups in the resting state, during CPET and recovery after the test. Conclusions: People with epilepsy present lower aerobic fitness than the general population. This fact seems to be associated with sedentary habits. Moreover, the practice of vigorous exercise seems to have a beneficial effect for people with epilepsy, characterized by a reduction in epileptiform discharges in the phases of exercise and recovery compared with the resting condition. It seems that there are no peculiarities in the physiological responses during incremental exercise that required a differential care in assessing the aerobic fitness of these people. / TEDE / BV UNIFESP: Teses e dissertações

Orientador: Luiz Eduardo Gomes Garcia Betting / Resumo: O padrão eletroencefalográfico mais comum em pacientes críticos é o distúrbio da atividade de base. Ondas trifásicas (OTs) constituem um padrão periódico classicamente relacionado às encefalopatias metabólicas. A maioria dos pacientes com OTs tem alteração do nível de consciência, e acredita-se que este padrão represente disfunção tálamo-cortical. Entretanto, o significado exato e o mecanismo das OTs permanecem desconhecidos. O objetivo principal deste estudo foi avaliar a origem das OTs utilizando o eletroencefalograma quantitativo (EEGq) e a tomografia computadorizada de crânio (TCC). 28 pacientes foram investigados. A análise dos focos das OTs foi realizada nas descargas promediadas para cada um dos indivíduos. Os mapas dos focos foram extraídos desta avaliação. As TCs foram submetidas à normalização e segmentação automática da substância cinzenta. Finalmente, uma análise de correlação voxel-a-voxel de todo o grupo foi realizada entre os mapas dos focos das OTs e as imagens da substância cinzenta. A análise do foco mostrou envolvimento principalmente do cíngulo anterior. A análise de correlação revelou áreas de correlação moderada positiva (giro do cíngulo posterior; r = 0,5) e negativa (caudado; r = -0,51) entre os métodos. / Abstract: The most frequent electroencephalographic pattern in critically ill patients is diffuse background slowing. Triphasic waves (TW) is a periodic pattern classically described in metabolic encephalopathic patients. Most patients with TW have altered level of consciousness, and this pattern is believed to represent thalamus-cortical dysfunction. However, the exact meaning and mechanism of TWs remains unknown. The main objective of this study was to evaluate the source of TWs using quantitative electroencephalogram (qEEG) and tomography (CT). 28 patients were investigated. Source analysis was performed in the averaged TWs for each individual. Source maps were extracted from this evaluation. CTs were submitted to normalization and automatic segmentation of gray matter. Finally, voxel-wise correlation analysis for the whole group was conducted between qEEG source maps and gray matter images. Source analysis showed involvement mainly of the anterior cingulate cortex. Correlation analysis disclosed moderate positive (posterior cingulate; r = 0.5) and negative (caudate; r = -0.51) correlations between the methods. / Mestre

abstract: Beneath the epidermis, the human body contains a vibrant and complex ecology of interwoven rhythms such the heartbeat, the breath, the division of cells, and complex brain activity. By repurposing emergent medical technology into real-time gestural sound controllers of electronic musical instruments, experimental musicians in the 1960s and 1970s – including David Rosenboom – began to realize the expressive potential of these biological sounds. Composers experimented with breath and heartbeat. They also used electroencephalography (EEG) sensors, which register various types of brain waves. Instead of using the sound of brain waves in fixed-media pieces, many composers took diverse approaches to the challenge of presenting this in live performance. Their performance practices suggest different notions of embodiment, a relationship in this music which has not been discussed in detail. Rosenboom reflects extensively on this performance practice. He supports his EEG research with theory about the practice of biofeedback. Rosenboom’s work with EEG sensors spans several decades and continue today, which has allowed him to make use of advancing sensing and computing technologies. For instance, in his 1976 On Being Invisible, the culmination of his work with EEG, he makes use of analyzed EEG data to drive a co-improvising musical system. In this thesis, I parse different notions of embodiment in the performance of EEG music. Through a critical analysis of examples from the discourse surrounding EEG music in its early years, I show that cultural perception of EEG sonification points to imaginative speculations about the practice’s potentials; these fantasies have fascinating ramifications on the role of the body in this music’s performance. Juxtaposing these with Rosenboom, I contend that he cultivated an embodied performance practice of the EEG. To show how this might be manifest in performance, I consider two recordings of On Being Invisible. As few musicologists have investigated this particular strain of musical experimentalism, I hope to contextualize biofeedback musicianship by offering an embodied reading of this milestone work for EEG. / Dissertation/Thesis / Masters Thesis Music 2015

Neuromodulation is being recognized as “technology impacting on the neural interface” And noninvasive brain stimulation (NIBS) is becoming an interesting alternative for this interface. Transcranial pulsed current stimulation (tPCS) is emerging as an option in the field of neuromodulation as a technique that employs weak, pulsed current at different frequency ranges, inducing electrical fields that reach cortical and subcortical structures; however, little is known about its properties and mechanistic effects on electrical brain activity and how it can modulate its oscillatory patterns. Moreover, there is not clear understanding in how tPCS can affect cognition and behavior or its neurophysiological correlates as indexed by autonomic responses. This research looked at the mechanisms behind tPCS in four randomized clinical trials; the main aim of each experiment was to evaluate the effects of tPCS in quantitative electroencephalography (qEEG) and cognitive-behavioral testing by exploring different parameters of stimulation. Based in the findings obtained per experiment, tPCS can be defined as a safe and tolerable technique that modulates the power spectrum of qEEG signals by means of applied randomized frequencies in a pre-defined range, tPCS also facilitates connectivity in the area of influence by the electrical field and this has an impact on optimization of performance by decreasing reaction times (RT) in attention switching task and by facilitating wide-ranging network processing as in the case of arithmetic functioning. This work also delivered an insight about the potential that tPCS has for future clinical applications.