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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Feedback efficiency and training effects during alpha band modulation over the sensorimotor cortex / Die Wirksamkeit von Feedback und Trainingseffekten während der Alphaband Modulation über dem menschlichen sensomotorischen Cortex

Sollfrank, Teresa January 2015 (has links) (PDF)
Neural oscillations can be measured by electroencephalography (EEG) and these oscillations can be characterized by their frequency, amplitude and phase. The mechanistic properties of neural oscillations and their synchronization are able to explain various aspects of many cognitive functions such as motor control, memory, attention, information transfer across brain regions, segmentation of the sensory input and perception (Arnal and Giraud, 2012). The alpha band frequency is the dominant oscillation in the human brain. This oscillatory activity is found in the scalp EEG at frequencies around 8-13 Hz in all healthy adults (Makeig et al., 2002) and considerable interest has been generated in exploring EEG alpha oscillations with regard to their role in cognitive (Klimesch et al., 1993; Hanselmayr et al., 2005), sensorimotor (Birbaumer, 2006; Sauseng et al., 2009) and physiological (Lehmann, 1971; Niedermeyer, 1997; Kiyatkin, 2010) aspects of human life. The ability to voluntarily regulate the alpha amplitude can be learned with neurofeedback training and offers the possibility to control a brain-computer interface (BCI), a muscle independent interaction channel. BCI research is predominantly focused on the signal processing, the classification and the algorithms necessary to translate brain signals into control commands than on the person interacting with the technical system. The end-user must be properly trained to be able to successfully use the BCI and factors such as task instructions, training, and especially feedback can therefore play an important role in learning to control a BCI (Neumann and Kübler, 2003; Pfurtscheller et al., 2006, 2007; Allison and Neuper, 2010; Friedrich et al., 2012; Kaufmann et al., 2013; Lotte et al., 2013). The main purpose of this thesis was to investigate how end-users can efficiently be trained to perform alpha band modulation recorded over their sensorimotor cortex. The herein presented work comprises three studies with healthy participants and participants with schizophrenia focusing on the effects of feedback and training time on cortical activation patterns and performance. In the first study, the application of a realistic visual feedback to support end-users in developing a concrete feeling of kinesthetic motor imagery was tested in 2D and 3D visualization modality during a single training session. Participants were able to elicit the typical event-related desynchronisation responses over sensorimotor cortex in both conditions but the most significant decrease in the alpha band power was obtained following the three-dimensional realistic visualization. The second study strengthen the hypothesis that an enriched visual feedback with information about the quality of the input signal supports an easier approach for motor imagery based BCI control and can help to enhance performance. Significantly better performance levels were measurable during five online training sessions in the groups with enriched feedback as compared to a conventional simple visual feedback group, without significant differences in performance between the unimodal (visual) and multimodal (auditory–visual) feedback modality. Furthermore, the last study, in which people with schizophrenia participated in multiple sessions with simple feedback, demonstrated that these patients can learn to voluntarily regulate their alpha band. Compared to the healthy group they required longer training times and could not achieve performance levels as high as the control group. Nonetheless, alpha neurofeedback training lead to a constant increase of the alpha resting power across all 20 training session. To date only little is known about the effects of feedback and training time on BCI performance and cortical activation patterns. The presented work contributes to the evidence that healthy individuals can benefit from enriched feedback: A realistic presentation can support participants in getting a concrete feeling of motor imagery and enriched feedback, which instructs participants about the quality of their input signal can give support while learning to control the BCI. This thesis demonstrates that people with schizophrenia can learn to gain control of their alpha oscillations recorded over the sensorimotor cortex when participating in sufficient training sessions. In conclusion, this thesis improved current motor imagery BCI feedback protocols and enhanced our understanding of the interplay between feedback and BCI performance. / Die Wirksamkeit von Feedback und Trainingseffekten während der Alphaband Modulation über dem menschlichen sensomotorischen Cortex
12

Neurofeedbacktraining bei AD(H)S : wie wirkungsvoll ist es in der Praxis?.

Stüber, Nadja. January 2009 (has links)
Zugl.: Konstanz, Universiẗat, Diss., 2008.
13

Neurofeedbacktraining bei AD(H)S wie wirkungsvoll ist es in der Praxis?

Stüber, Nadja January 2008 (has links)
Zugl.: Konstanz, Univ., Diss., 2008
14

Auswirkungen der Selbstwirksamkeit auf den Effekt eines Theta/Beta Neurofeedbacktrainings bei Kindern mit Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung / Influence of self-efficacy on the effect of a theta/beta neurofeedback training in children with ADHD

Schmiedeke, David 29 July 2020 (has links)
No description available.
15

Effects of Treatment Expectancy on Self-Report and Neuropsychological Outcomes in Neurofeedback for Young Adults Seeking Treatment for Attention-Deficit/Hyperactivity Disorder

Lee, Grace J. January 2018 (has links)
No description available.
16

Avaliação dos efeitos do treinamento em neurofeedback sobre o desempenho cognitivo de adultos universitários / Evaluation of neurofeedback training on cognitive performance of college students

Appolinario, Fabio 17 December 2001 (has links)
O neurofeedback é um processo psicofisiológico de aprendizagem por meio do qual o indivíduo obtém controle sobre a freqüência de suas ondas cerebrais. Este estudo objetivou avaliar o efeito do treinamento do ritmo beta inferior (12-15Hz) sobre o córtex sensoriomotor e a concomitante inibição do ritmo teta (4-8Hz) na mesma área, sobre o desempenho atencional, mnemônico e cognitivo de adultos normais de nível universitário. Formou-se um grupo experimental e um grupo controle com 11 sujeitos cada, com idade média de 25,7 anos, estudantes de uma instituição de ensino superior particular em São Paulo. Todos os sujeitos foram submetidos a pré e pós-testes de inteligência não-verbal (Matrizes Progressivas de Raven Escala Avançada), verbal (V-47), atenção (D2) e memória (Fator M Bateria Cepa). O experimento, que durou dois meses, submeteu os sujeitos experimentais a 36 sessões (em média) de treinamento em neurofeedback, com a duração de 15 minutos cada e freqüência de três vezes por semana. Os resultados indicaram uma melhora significante nos processos atencionais, mnemônicos (icônicos) e edutivos (inteligência não-verbal). Não foram obtidas melhoras significantes nos processos mnemônicos (ecóicos) e reprodutivos (inteligência verbal). A comparação do grupo experimental com o grupo controle indicou a não relevância do efeito aprendizagem (teste-reteste) nas tarefas utilizadas para a avaliação dos sujeitos / Neurofeedback is a psychophysiological process where visual stimuli and sounds are employed to reinforce voluntary control over EEG patterns. This study evaluated the effect of low beta (12-15Hz) increase and theta (4-8Hz) inhibit training over sensorimotor cortex on attention, memory and cognitive performance of young adults college students. Experimental and control groups were formed by 11 volunteers subjects each, aging 25,7 years on average. All subjects were submitted to pre and post evaluations of non-verbal (Ravens Advanced Progressive Matrices) and verbal intelligence (V-47 test), attention (D2 test) and memory (Fator M Bateria Cepa). The experiment was conducted along two months, subjects having an average of 36 sessions (15 minutes each), three times a week. Results provide strong evidences of significant improvement on attention, visual memory and non-verbal intelligence (eduction). However, it could not be found evidence of significant improvement on auditory memory or verbal intelligence (reproduction). The experimental and control comparision did not indicate test-retest effects on the experiment
17

Avaliação dos efeitos do treinamento em neurofeedback sobre o desempenho cognitivo de adultos universitários / Evaluation of neurofeedback training on cognitive performance of college students

Fabio Appolinario 17 December 2001 (has links)
O neurofeedback é um processo psicofisiológico de aprendizagem por meio do qual o indivíduo obtém controle sobre a freqüência de suas ondas cerebrais. Este estudo objetivou avaliar o efeito do treinamento do ritmo beta inferior (12-15Hz) sobre o córtex sensoriomotor e a concomitante inibição do ritmo teta (4-8Hz) na mesma área, sobre o desempenho atencional, mnemônico e cognitivo de adultos normais de nível universitário. Formou-se um grupo experimental e um grupo controle com 11 sujeitos cada, com idade média de 25,7 anos, estudantes de uma instituição de ensino superior particular em São Paulo. Todos os sujeitos foram submetidos a pré e pós-testes de inteligência não-verbal (Matrizes Progressivas de Raven Escala Avançada), verbal (V-47), atenção (D2) e memória (Fator M Bateria Cepa). O experimento, que durou dois meses, submeteu os sujeitos experimentais a 36 sessões (em média) de treinamento em neurofeedback, com a duração de 15 minutos cada e freqüência de três vezes por semana. Os resultados indicaram uma melhora significante nos processos atencionais, mnemônicos (icônicos) e edutivos (inteligência não-verbal). Não foram obtidas melhoras significantes nos processos mnemônicos (ecóicos) e reprodutivos (inteligência verbal). A comparação do grupo experimental com o grupo controle indicou a não relevância do efeito aprendizagem (teste-reteste) nas tarefas utilizadas para a avaliação dos sujeitos / Neurofeedback is a psychophysiological process where visual stimuli and sounds are employed to reinforce voluntary control over EEG patterns. This study evaluated the effect of low beta (12-15Hz) increase and theta (4-8Hz) inhibit training over sensorimotor cortex on attention, memory and cognitive performance of young adults college students. Experimental and control groups were formed by 11 volunteers subjects each, aging 25,7 years on average. All subjects were submitted to pre and post evaluations of non-verbal (Ravens Advanced Progressive Matrices) and verbal intelligence (V-47 test), attention (D2 test) and memory (Fator M Bateria Cepa). The experiment was conducted along two months, subjects having an average of 36 sessions (15 minutes each), three times a week. Results provide strong evidences of significant improvement on attention, visual memory and non-verbal intelligence (eduction). However, it could not be found evidence of significant improvement on auditory memory or verbal intelligence (reproduction). The experimental and control comparision did not indicate test-retest effects on the experiment
18

Die Wirksamkeit von Neurofeedback im Vergleich zum EMG-Biofeedback bei der Behandlung von ADHS-Kindern / Effectiveness of neurofeedback in comparison with EMG-biofeedback in the treatment of ADHD-children

Bakhshayesh, Ali Reza January 2007 (has links)
Seit vier Jahrzehnten werden verschiedene Neurofeedbackmethoden bei der Behandlung unterschiedlicher Störungen, unter anderem bei AD/HS-Kindern, eingesetzt. Die Grundlage der Anwendung von Neurofeedback bei dieser Störung besteht darin, dass die Kinder Auffälligkeiten in ihrem EEG zeigen. Dort treten im Vergleich zu unauffälligen Kindern vermehrt Theta-Gehirnwellen und weniger Beta-Gehirnwellen auf. Mittels Neurofeedback wird versucht, die Gehirnfunktionen zu korrigieren. Zahlreiche Einzellfallstudien bestätigen die Wirksamkeit dieser Therapiemethode bei der AD/HS-Behandlung. Bisher wurde jedoch keine Studie veröffentlicht, in der die Wirksamkeit von Neurofeedback mit einer Placebogruppe verglichen wurde. Ziel der vorliegenden Studie war es, die Wirksamkeit eines Theta/Beta-Neurofeedbacks (NF) bei der Behandlung von AD/HS-Kindern zu überprüfen und mit einem EMG-Biofeedback (BF) als Placebobedingung zu vergleichen. Es wurden 35 ADHS-Kinder (6 -14 Jahre; 26 Jungen und 9 Mädchen) untersucht. Nach Standarddiagnostik und Vergabe der AD/HS-Diagnose durch einen unabhängigen Psychotherapeuten wurden die Kinder per Zufall zwei Gruppen (NF: n = 18 bzw. BF: n = 17) zugeteilt. Alle Kinder beider Gruppen erhielten ein 30 Sitzungen umfassendes Training mittels Theta/Beta-Neurofeedback bzw. EMG-Biofeedback. Unmittelbar vor und nach dem Training wurden Intelligenz- bzw. Aufmerksamkeitsleistungen untersucht und Einschätzungen des Verhaltens von Eltern und Lehrern erhoben. Im Anschluss an das Training erfolgte eine erneute diagnostische Einschätzung durch einen unabhängigen Psychotherapeuten. Die EEG-Daten in der NF-Gruppe zeigen eine Reduktion der Theta/Beta-Quotienten im Laufe der NF-Sitzungen. Die EMG-Daten zeigen für die EMG-Biofeedback-Bedingung gleichfalls eine Reduktion der EMG-Amplitude. Die Ergebnisse der zweifaktoriellen Varianzanalysen mit Messwiederholung auf einem Faktor zeigen für die angewendeten diagnostischen Verfahren die erwarteten signifikanten Interaktionen zwischen Messzeitpunkt und Gruppe. Die Ergebnisse des t-Tests zeigen signifikante Verbesserungen in der Aufmerksamkeitsleistung, dem Intelligenzniveau und im Verhalten der Kinder aus der NF-Gruppe im Vergleich zu den Resultaten des Prä-Tests. Die EMG-Biofeedbackgruppe zeigt mit Ausnahme einer Erhöhung des Arbeitstempos in den Paper-Pencil-Aufmerksamkeitstests (die im CPT nicht repliziert werden konnte) keine signifikanten Verbesserungen relativ zum Prä-Test. Nach dem Training erhielten 55,6 % (n = 10) der AD/HS-Kinder aus der Neurofeedbackgruppe und 23,5 % (n = 4) der Kinder aus der EMG-Biofeedbackgruppe keine AD/HS-Diagnose nach den Kriterien der ICD-10. Der Chi-Quadrat-Test zeigt jedoch lediglich einen tendenziell bedeutsamen Unterschied (p = .086). Insgesamt bestätigen die Ergebnisse die Wirksamkeit des Neurofeedbacks bei der Behandlung von ADHS-Kindern im Vergleich mit einer Placebogruppe. Weitere Studien in diesem Bereich sind notwendig, um die Wirksamkeit des Neurofeedbacktrainings im Vergleich zu einer Placebomethode bei der ADHS-Behandlung zu untersuchen. / Neurofeedback (NF) has been introduced four decades ago as an alternative treatment for different disorders, one of these being Attention Deficit/Hyperactivity Disorder (AD/HD). As compared to a control group (non ADHD children), children diagnosed with ADHD show an increased frequency of Theta waves and a decreased frequency of Beta waves in their EEGs. A treatment consisting of NF-training attempts to correct these anomalies. There are numerous single case studies in this area but only a few controlled studies. Furthermore, there are no studies comparing the effect of NF in the treatment of ADHD with a placebo group. This study sets out to evaluate the effects of 30 (Theta/Beta) NF training sessions on ADHD symptoms and compare those with the effects of the placebo EMG-biofeedback (BF) training group. The subjects, consisting of 35 children both male (n = 26) and female (n = 9) between the ages of 6 and 14 diagnosed with ADHD by independent psychotherapists, were randomly assigned to either the treatment group (NF; n = 18) or the placebo group (BF; n = 17). In addition to the Theta/Beta quotient (in NF group) and EMG-Amplitude (in BF group) as seen during the sessions, pre and post measures of the subjects´ intelligence (Raven Test), paper-pencil attention test scores (bp/d2), Continuous Performance Task (CPT) as well as symptom ratings (MEF and FBB-HKS) from both teachers and parents were obtained. Finally, subjects were re-evaluated after treatment by independent psychotherapists. The results showed a significant decrease in the Theta/Beta quotient after the NF training and a significant decrease in the EMG-Amplitude after the BF-training. The results of an ANOVA with repeated measures showed significant differences between the treatment group (NF training) and the placebo (BF training) group in attention tests and symptom rating scores after treatment. Compared to the pre-test scores, subjects in the NF group showed significant improvements in attention scores, intelligence scores, and behaviour after the NF training sessions. The BF placebo group showed no significant improvements in any of the outcome variables except on the speed scale of the paper-pencil attention tests (this was incompatible with the results of CPT). Finally, 55.6% (n = 10) of the children in the NF training group were not diagnosed with ADHD (using ICD-10 criteria) at the time of the second evaluation. In the BF group, 23.5% (n = 4) were not diagnosed with ADHD by independent psychotherapists at the end of the BF training. The results indicate that NF training in comparing with a placebo method is an effective treatment method in the treatment of ADHD children. Further studies are necessary in comparing the effectiveness of NF training with more neutral placebo interventions in the treatment of children with ADHD.
19

Biofeedback e sua aplicabilidade nas psicopatologias - uma revisão sistemática

Silva, Priscilla Rezende 27 February 2018 (has links)
Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-06-18T13:40:42Z No. of bitstreams: 1 priscillarezendesilva.pdf: 1039823 bytes, checksum: 1dd3ace224b869dc4a10c45288993628 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-06-27T12:00:30Z (GMT) No. of bitstreams: 1 priscillarezendesilva.pdf: 1039823 bytes, checksum: 1dd3ace224b869dc4a10c45288993628 (MD5) / Made available in DSpace on 2018-06-27T12:00:30Z (GMT). No. of bitstreams: 1 priscillarezendesilva.pdf: 1039823 bytes, checksum: 1dd3ace224b869dc4a10c45288993628 (MD5) Previous issue date: 2018-02-27 / Dentre os tratamentos propostos para transtornos mentais, a terapia de biofeedback é uma das muitas abordagens utilizadas. Tal terapia tem como objetivo auxiliar o indivíduo a assumir a responsabilidade pelo seu bem-estar, englobando responsabilidades pelas mudanças cognitivas, emocionais e comportamentais necessárias para a obtenção de mudanças fisiológicas saudáveis. Neste trabalho de revisão sistemática objetivou-se pesquisar e averiguar em quais psicopatologias o biofeedback e o neurofeedback têm sido utilizados, bem como verificar a existência de evidências de sua eficácia nesses quadros. Foi realizada uma pesquisa em cinco bases de dados eletrônicas (PubMed/Medline, SCOPUS, Web of Science, PsycInfo e Scielo), utilizando-se combinações booleanas do termo “biofeedback” (AND) com termos retirados da Classificação Estatística Internacional de Doenças e Problemas Relacionados à Saúde – 10 (CID-10). A seguir, novas combinações foram empregadas adicionando o termo “intervention” às combinações descritas. Um total de 14.350 estudos foram incluídos no conjunto de dados. Foram analisados estudos originais, cujo objetivo era investigar a eficácia do biofeedback no tratamento de psicopatologias, escritos em português e/ou inglês publicados entre os anos de 2012-2017. Após o cumprimento de várias etapas de seleção, foram incluídos 49 estudos no conjunto de dados final e analisados de acordo com a: descrição da amostra (patologia; idade; tipo de biofeedback), desenho (Randomização; Controle, Cegamento; cálculo do N, Follow-up, Registro, Tamanho de efeito, análise por intenção de tratar, Multicêntrico, Piloto), protocolo (número de sessões de treinamento e de intervenção, duração da sessão de intervenção, frequência das sessões e duração da pesquisa). As psicopatologias mais frequentes foram transtorno de déficit de atenção e hiperatividade, transtorno depressivo maior, transtorno do espectro autista, dependência de álcool, compulsão alimentar e estresse. A maioria (51,02%) dos estudos analisados não utilizou medidas de tamanho de efeito e apenas um quinto (20,42%) encontrou, efetivamente, algum efeito nas intervenções com biofeedback ou neurofeedback. Todos os 13 estudos nos quais foi apresentado algum efeito do bio ou neurofeedback continham importantes falhas metodológicas. Considerados todos os aspectos metodológicos e os vieses de cada uma das falhas, verifica-se que nenhum dos artigos conseguiu contemplar todos os requisitos metodológicos para que se pudesse afirmar a eficácia do tratamento através do biofeedback e o neurofeedback. São necessários estudos mais rigorosos para que se possa afirmar a aplicabilidade e a eficácia do biofeedback e neurofeedback no manejo de psicopatologias. / Among the proposed treatments for mental disorders, biofeedback therapy is one of many approaches. Such therapy aims to assist the individual to take responsibility for their well-being, encompassing responsibility for the cognitive, emotional, and behavioral changes necessary to effect healthy physiological changes. In this systematic review we aimed to investigate in which psychopathologies biofeedback and neurofeedback have been used, as well as to verify the existence of evidence of its effectiveness in these psychopathologies. A search was carried out in five electronic databases (PubMed / Medline, SCOPUS, Web of Science, PsycInfo and Scielo), using boolean combinations of the term "biofeedback" (AND) with terms derived from the International Classification of Diseases for Mortality and Morbidity Statistics- 10 (ICD-10). Next, new combinations were employed by adding the term "intervention" to the combinations described. A total of 14,350 studies were included in the data set. We analyzed original studies, whose objective was to investigate the efficacy of biofeedback in the treatment of psychopathologies, written in Portuguese and / or English and published between the years of 2012-2017. After completing several selection steps, 49 studies were included in the final data set and analyzed according to: sample description (pathology; age; type of biofeedback), design (Randomization; Control, Blinding; Statistic for sample size, Follow-up, size of effect, intention-to-treat, Multicenter, Pilot) and protocol (number of training sessions, number of intervention sessions, duration of intervention session, frequency of sessions and duration of research). Biofeedback and neurofeedback were found mostly used in attention deficit hyperactivity disorder, major depressive disorder, autism spectrum disorder, alcohol dependence, binge eating, and stress. Most (51.02%) of the studies analyzed did not use effect size measures and only one fifth (20.42%) did indeed find any effect on interventions with biofeedback or neurofeedback. All 13 studies that found some bio or neurofeedback effect contained important methodological flaws. Considering all the methodological aspects and biases of each one of the failures, it was verified that none of the studies was able to contemplate all the methodological requirements so that the effectiveness of the treatment with the biofeedback and the neurofeedback could be affirmed. More rigorous studies are needed to establish the applicability and efficacy of biofeedback and neurofeedback in the management of psychopathologies.
20

Etude du rôle des oscillations dans les états attentionnels endogènes et exogènes : les nouvelles méthodes en neurophénoménologie / Investigating the role of oscillations in endogenous and exogenous attentional states : novel methods in neurophenomenology

Brandmeyer, Tracy 17 February 2017 (has links)
Le travail présenté dans cette thèse vise à nous amener à une meilleure compréhension des relations fines entre ce que nous expérimentons phénoménologiquement sous la forme d'états mentaux, et les effets sous-jacents et potentiellement causaux sur l'activité neuronale. Afin d'étendre notre compréhension scientifique de l'expérience consciente, nous avons d'abord mis l'accent sur un phénomène appelé la pensée spontanée ou vagabondage de l'esprit. Notre paysage intérieur est un aspect essentiel et complexe de notre expérience humaine, avec des recherches suggérant que les gens sont engagés dans une forme de dialogue intérieur sans rapport avec leur environnement immédiat 50% de leur temps de veille. De plus, le vagabondage de l'esprit a constamment été associé à un affect négatif, même lorsque son contenu est positif. Il est alors intéressant de noter que les fondements de la plupart des pratiques méditatives et contemplatives sont la formation de l'observation flexible et continue des états mentaux et de l'expérience sensorielle, le développement d'une attention soutenue et la culture de la conscience métacognitive. Étant donné que nous ne sommes généralement pas au courant de la fluctuation temporelle de ces états mentaux dans le temps (vagabondage de l'esprit), les méditants sont des sujets idéaux pour obtenir de manière précise des rapports phénoménologiques et des descriptions des états à la première personne. Ainsi, nous avons conçu un paradigme nouveau basé sur présentation de sondage d'expérience aux méditants afin de mieux comprendre les mesures dynamiques de l'EEG (Electroencéphalographie) pendant la méditation. Nos résultats suggèrent que la pratique experte de méditation est associée à une fréquence atténuée de la pensée spontanée et que l'entraînement à la méditation réduit par la suite la susceptibilité de l'esprit à errer, menant à des périodes d'absorption méditative rapportées comme étant plus longues. Les augmentations de l'activité thêta (4-7 Hz) sur les régions thêta frontales médianes ainsi que l'activité alpha (9-12 Hz), principalement focalisée sur le cortex somatosensoriel, semblent être des marqueurs d'états méditatifs soutenus par rapport au vagabondage mental. Sur la base de la robustesse de l'activité thêta de la ligne médiane frontale chez les méditants avancés, ainsi qu'une multitude de résultats démontrant que l'activité thêta frontale serait le pilier du contrôle cognitif via l'intégration et l'échange d'informations de longue portée, nous avons développé un protocole de neurofeedback méthodologiquement nouveau et exhaustif dans le but d'entraîner l'activité thêta (3.5-6.5 Hz) de la ligne médiane frontale Fz, en donnant comme instruction à nos sujets de s'engager dans des techniques de respiration et de relaxation similaires à la méditation. Nous avons constaté que les sujets qui ont reçu le vrai neurofeedback ont été capables de moduler significativement leur activité thêta Fz (3-7 Hz) à travers huit séances de neurofeedback par rapport aux sujets contrôles qui ont reçu un feedback apparié. Nous avons également observé des modulations significatives dans les bandes de fréquences alpha (9-11 Hz) et bêta (13-20 Hz) chez les sujets qui ont reçu l'entraînement réel de neurofeedback, ainsi que des améliorations sur plusieurs mesures des fonctions exécutives. Nos résultats réduisent davantage l'écart explicatif en reliant caractéristique neurophysiologique et données à la nature phénoménologique de notre experience. / The work presented in this thesis aims to extend our scientific understanding of the subtle relationships between our phenomenological experience of specific states of consciousness, and the corresponding and potentially causal effects on neural activity. In our first experiment, we focused on a phenomenon referred to as spontaneous thought or mind wandering. Our vastly complex inner landscape is an essential aspect of our conscious experience, with research suggesting that people are engaged in some form of inner dialogue unrelated to their surroundings 50% of waking hours. These ongoing trains of thought have been consistently linked to reports of negative affect, even when the specific content is positive. Interestingly, the cornerstones of most meditation and contemplative practices are; a) training the continuous and flexible monitoring of mind wandering and sensory experience, b) the cultivation of sustained attention, and c) enhanced metacognitive awareness. Given that we are generally unaware of mind wandering when it occurs, meditation practitioners may provide more accurate first person phenomenological reports and descriptions of these temporally fluctuating states given their respective training. Thus, we designed a novel paradigm based on experience sampling probe presentations to gain insight into the dynamic measures of mental activity and EEG during meditation. Our findings suggest that meditation expertise is associated with an attenuated frequency of mind wandering, and that meditation training reduces the susceptibility of the mind to wander subsequently leading to longer periods of reported meditative absorption. Increases in theta activity (4-7 Hz) over frontal midline regions of the cortex, and alpha activity (9-12 Hz) primarily focused over the somatosensory cortex, appear to be markers of sustained meditative states when compared to mind wandering. Based on the robustness of the frontal midline theta in advanced meditators, alongside a multitude of findings demonstrating that frontal theta may serve as the backbone for cognitive control via long range information integration in neural networks throughout the brain, we then developed a methodologically novel and exhaustive neurofeedback protocol with the aim of training frontal midline theta (3.5-6.5 Hz at electrode site Fz) by means of instructing our subjects to engage in focused breathing and other techniques similar to meditation. After eight training sessions, we found that subjects who received real neurofeedback were able to significantly modulate and increase theta activity (3-7 Hz) over frontal regions, whereas subject's receiving age and gender matched sham (pseudo) feedback were not. We additionally observed significant modulations in both the alpha (9-11 Hz) and beta bands (13-20 Hz) in subjects who received real neurofeedback training. Together, these findings provide evidence that we can successfully connect neurophysiological features and data to the phenomenological nature of our subjective experience.

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