Il apparaît, suite aux résultats de plusieurs études comportementales et d’imagerie cérébrale, que les hormones gonadiques peuvent moduler le fonctionnement cérébral chez la femme. Les asymétries cérébrales fonctionnelles (ACFs), en particulier, changeraient en fonction du niveau de progestérone et d’œstrogène. On a également observé que lorsque le taux d’œstrogène est bas, les performances aux tâches impliquant l’hémisphère droit sont améliorées. Par contre, les preuves de l’action physiologique de ces deux hormones sur le cerveau ne sont pas très nombreuses. Le peu d’études d’électrophysiologie cognitive qui ont porté sur les effets du cycle menstruel ont rapporté que la composante P300 y serait sensible. Aucune n’a cependant utilisé une tâche d’habileté spatiale ou de rotation mentale qui sont connues pour impliquer davantage l’hémisphère droit. Le but de la présente étude est de documenter les changements électrocorticaux reliés aux variations hormonales lors d’une tâche de rotation mentale. Notre hypothèse de départ est que le taux d’œstrogène influencera l’activité électrocorticale et la latéralisation. Les potentiels évoqués cognitifs ont été comparés chez les mêmes femmes (n=12) lors d’une tâche de rotation mentale, répétée à deux périodes du cycle menstruel. Nos résultats démontrent que la condition de rotation induit une latéralisation de l’activité pariétale, vers l’hémisphère gauche, quand le niveau d’œstrogène est bas. Par contre, lorsque le niveau d’œstrogène est élevé, il n’y a aucune latéralisation. Par ailleurs, nous avons observé une augmentation de l’amplitude de la P300 lors du niveau oestrogénique élevé. En conclusion, les fluctuations oestrogéniques du cycle menstruel ont un impact sur la latéralisation de l’activité électrocorticale, lors d’un effort de rotation mentale. / After many behavioral and some neuroimaging studies, it appears that the gonadic hormones can modulate the neuronal function of women's brain. In particular, the functional cerebral asymmetries can be affected by the level of progesterone and estrogens. It has been observed that when the level of estrogen is low, the performance at task that engages more the right hemisphere is enhanced. However, there is a lack of evidence for the physiological actions of these two hormones on the brain. The few event-related potential studies taking into account the menstrual cycle effects, had noticed that the component P300 can be affected. No electrophysiological study has used a mental rotation task or spatial ability tests which are known for their right hemisphere dominance. The aim of the present research is to document the effect of hormonal variations on the electrocortical activity, using a mental rotation task. Our hypothesis is that estrogen levels affect electrocortical activity and lateralization. The ERPs were compared in the same women (n = 12) during a mental rotation task, repeated over two periods of the menstrual cycle. Our results show a lateralization of the left parietal activity when estrogen levels are low and during the rotation. Whereas when the estrogen level is high, there is no lateralization. In addition, we observed an increase in the amplitude of P300 for this same high level. In conclusion, estrogens fluctuations associated with the menstrual cycle have an impact on the lateralization of electrocortical activity, when a mental rotation is needed.

Submitted by Viviane Borim de Goes null (viviane_borim@hotmail.com) on 2018-03-19T11:32:37Z No. of bitstreams: 1 Dissertação_Versão Final_Viviane borim.pdf: 1660097 bytes, checksum: 5a7b7a20f668bfe605743bc3785b11ab (MD5) / Approved for entry into archive by Satie Tagara (satie@marilia.unesp.br) on 2018-03-19T15:00:17Z (GMT) No. of bitstreams: 1 goes_vb_me_mar.pdf: 1660097 bytes, checksum: 5a7b7a20f668bfe605743bc3785b11ab (MD5) / Made available in DSpace on 2018-03-19T15:00:17Z (GMT). No. of bitstreams: 1 goes_vb_me_mar.pdf: 1660097 bytes, checksum: 5a7b7a20f668bfe605743bc3785b11ab (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O processamento da informação auditiva é item fundamental para a função social, de modo a estar envolvido com domínios cognitivos como a função executiva, memória e linguagem. Isso permite ao indivíduo compreensão da linguagem e contribui posteriormente para expressão da mesma durante a comunicação. Nesse mesmo contexto, durante a situação comunicativa, a mesma é modulada pelo organismo por meio do funcionamento do sistema nervoso autônomo. Esse sistema também se relaciona com a cognição e esta, por sua vez, é fundamental para a aquisição e desenvolvimento da linguagem. Em tarefa executiva de linguagem ocorre o envolvimento dos domínios cognitivos acima citados. Dessa maneira, sugere-se que o processamento da informação auditiva se relaciona com o controle autonômico da frequência cardíaca e que tarefa executiva de linguagem pode modificar o desempenho dos potenciais relacionados a evento, de modo a representar maior esforço cognitivo, resultando em menor atividade da modulação parassimpática. Objetivos: Investigar a relação entre os potenciais relacionados a evento e a modulação parassimpática da frequência cardíaca antes e após tarefa executiva de linguagem e verificar os efeitos de tal tarefa. Método: Participaram desta pesquisa 42 mulheres saudáveis entre 18 e 30 anos de idade, com ensino médio completo, divididas em dois grupos: fonológico (n=21) e semântico (n=21). Após a colocação da cinta do cardiofrequencímetro na região do processo xifoide, a voluntária foi orientada a permanecer 10 minutos em repouso, sendo realizado os registros da frequência cardíaca. Em seguida, na primeira fase considerada pré-teste, foi iniciado o registro dos potenciais relacionados a evento com estimulação binaural nos parâmetros de frequência (1KHz/ 2KHz) paradigma oddball, concomitante ao registro da frequência cardíaca. Após, na segunda fase considerada teste, a tarefa executiva de linguagem foi realizada por meio do teste de fluência verbal fonológica para o grupo fonológico e teste de fluência verbal semântica para o grupo semântico. Na terceira fase considerada pós-teste, os registros dos potenciais relacionados a evento e da frequência cardíaca foram realizados utilizando os mesmos protocolos descritos na fase pré-teste. Resultados: Houve correlação da latência de P3 com o índice pNN50 no grupo fonológico pós-teste de fluência verbal fonológica (p=0,036). Na comparação dos potenciais relacionados a evento entre os momentos pré e pós-teste, foi observado diferença média e estatisticamente significante entre a latência de P3 após teste de fluência verbal fonológica, no grupo fonológico (p=0,020). Na comparação da modulação parassimpática da frequência cardíaca entre os momentos repouso, pré e pós-teste, houve diferença entre os índices RMSSD (p=0,007), pNN50 (p=0,035) e SD1 (p=0,007) após teste de fluência verbal fonológica, no grupo fonológico. Conclusão: Houve associação entre os potenciais relacionados a evento com a modulação parassimpática da frequência cardíaca após tarefa executiva de linguagem, em específico o teste de fluência verbal fonológica. Este teste, por sua vez, de forma significante, aumentou a latência de P3 e diminuiu a modulação parassimpática da frequência cardíaca. / The processing of auditory information is a fundamental element for the social function, involved with cognitive domains such as executive function, memory and language. This allows the individual to understand the language and subsequently contributes to its expression during communication. In the same context, during the communicative situation, it is modulated by the organism through the functioning of the autonomic nervous system. This system is also related to cognition and this, in turn, is fundamental for the acquisition and development of language. In the executive task of language, the involvement of the cognitive domains mentioned above occurs. Thus, it is suggested that the auditory information processing is related to the autonomic control of the heart rate and that the executive task of language can modify the performance of the event-related potentials, in order to represent greater cognitive effort, resulting in less activity of the parasympathetic modulation. Objective: To investigate the relationship between event-related potentials and the parasympathetic heart rate modulation before and after language task and verify the effects of such a task. Method: We analyzed 42 healthy women between 18 and 30 years of age with complete high school, were divided into two groups: phonological (n = 21) and semantic (n = 21). After placement of the cardiofrequency measuring strap in the xiphoid process region, the volunteer was instructed to remain at rest for 10 minutes, and heart rate records were performed. Then, in the first phase considered as a pre-test, the event-related potentials with binaural stimulation were started in the frequency parameters (1KHz/ 2KHz) oddball paradigm, concomitant to heart rate recording. After, the second phase, the executive task of language was performed using the phonological verbal fluency test for the phonological group and the semantic verbal fluency test for the semantic group. In the third phase considered post-test, the register the event-related potential and heart rate were performed using the same protocols described in the pre-test phase. Results: There was a correlation between the latency of P3 and the pNN50 index in the phonological group post-test of phonological verbal fluency (p = 0.036). In the comparison of the event-related potentials between the pre- and post-test moments, a mean and statistically significant difference between the P3 latency after phonological verbal fluency test was observed in the phonological group (p = 0.020). There was a difference between the RMSSD (p = 0.007), pNN50 (p = 0.035) and SD1 (p = 0.007) indices in the comparison of the parasympathetic heart rate modulation between the resting, pre and post-test moments phonological verbal fluency, in the phonological group. Conclusion: There was association between the event-related potentials with the parasympathetic heart rate modulation after executive language task, specifically the phonological verbal fluency test. This test, in turn, significantly increased P3 latency and decreased parasympathetic heart rate modulation.

Made available in DSpace on 2016-03-15T19:39:36Z (GMT). No. of bitstreams: 1 Camila Campanha.pdf: 2234537 bytes, checksum: 330a99b6a7ecb7751a711132a17ecb0b (MD5) Previous issue date: 2010-12-14 / Fundo Mackenzie de Pesquisa / Decisions engage careful consideration of the risks and benefits involved in a particular choice. As we live in society, these choices are not only related to our personal interests. Therefore, social interaction has an important role, because the other is part of the context in which we evaluate decisions. Previous studies show the importance of trust and empathy in decision-making processes. In fact, Boudreau, McCubbins and Coulson (2009) showed that trust in another person interferes with behavioral response and also in event related potentials recorded during the test. However, as in other studies, trust was studied by the instruction given to participants that they will base their choices by reports made by another human being - unknown person. The use of an unknown person limits the interpretation of the role of trust involved in decision making processes. Thus this study aims to investigate the decision making processes in a task in which the participant brought to the lab a person (a trusted friend) that act as reporter. In addition, there are few studies investigating event-related potentials in tasks of social decision. Therefore, this study aim to understand the role of trust in decision-making by analysis of behavioral performance in an adapted version of the Ultimatum Game task and also investigate the event related potentials collected simultaneously. Among the main findings, we found a change in the perception of fairness (in fact there was no difference) and, consequently, a change in decision-making with more acceptance of proposals on the condition of interaction with the trusted person than other proposers. Moreover, the P3, FN and LPC potential were modulated by the impact of trust, and by moral internalization, and differed between genders. This study may increase knowledge about the neurobiological bases of behavior and decision making processes involving social interaction, trust and empathy. / Decisões envolvem considerações cuidadosas sobre os riscos e benefícios envolvidos em uma determinada escolha. Por vivermos em sociedade, estas constantes escolhas estão relacionadas não só aos nossos interesses pessoais. Nesse sentido, a interação social tem um importante papel, pois o outro faz parte de um contexto no qual avaliamos possíveis decisões. Estudos prévios mostram a importância da confiança e da empatia em processos de decisão. Nessa direção, Boudreau, McCubbins e Coulson (2009) mostraram que a confiança no outro interfere na resposta comportamental e também nos potenciais cognitivos registrados durante o teste. Entretanto, assim como em outros estudos, a confiança foi estudada pela orientação ao participante de que este estaria sendo orientado por outro ser - humano uma pessoa desconhecida). O uso de uma pessoa desconhecida limita a discussão a respeito do papel da confiança envolvida em processos decisórios. Dessa forma este estudo busca investigar os processos decisórios em uma tarefa na qual o participante levou ao laboratório uma pessoa (amigo de alta confiança) que funcionará como propositor. Além disso, ainda são poucos os estudos investigando potenciais relacionados a evento em tarefa de decisão social. Com isso, este estudo buscou compreender o papel da confiança em processos de decisão analisando o desempenho comportamental em tarefa adaptada do teste Ultimatum Game e também os potenciais cognitivos coletados simultaneamente. Entre os principais achados, encontrou-se uma alteração na percepção de justiça (o que na realidade não havia diferença) e, por conseqüência, uma alteração na tomada de decisão com maior aceite de propostas na condição de interação com a pessoa de confiança em comparação com os outros propositores. Além disso, os potenciais P3, FN e LPC foram modulados pelo impacto da confiança, pela interferência da internalização moral e apresentaram diferenças entre gênero. Este estudo pode aumentar o conhecimento sobre as bases neurobiológicas e comportamentais de processos decisórios envolvendo interação social, confiança e empatia.

Made available in DSpace on 2016-03-15T19:40:04Z (GMT). No. of bitstreams: 1 Claudia Aparecida Valasek.pdf: 3051872 bytes, checksum: 74892c88676016fa1df9dfd31b5764d2 (MD5) Previous issue date: 2013-02-07 / Fundação de Amparo a Pesquisa do Estado de São Paulo / In the last decades the research interests in the false memory phenomenon have been amplified. The number of studies in the literature that investigate the electrophysiological components underlying the true recognition and the false recognition is still scarce, principally with respect to children and adolescents with autism diagnostic. The aim of this study was to analyze the behavioral differences in the performance of the subjects in the adapted Roediger and McDermott paradigm task in both groups and verify the presence of electrophysiological components in the recognition phase. Fifteen children/adolescents participated in the experiment. Seven of the subjects belonged to the autism diagnostic group (mean 15 + 3,6) and 8 subjects belonged to the typical development group (mean 10,7 + 2,5). The behavioral results showed that there was not a significant difference in the rates of correctness on the recognition of the target word, error by critical clue and critical distractor. Contrary to what was expected, this difference was also not observed in the children with autism. This might indicate that a literal information processing does occur in this kind of task. The analysis of the electrophysiological data in the recognition phase revealed the old/new component (500-1000ms) that presents higher amplitude for true recognition than for false recognition. It is interesting to notice that this component was observed on both typical development and autism groups. Moreover, it has been observed the low amplitude P1 component for correct rejection of critical clues in comparison to other types of correct answers. This component seems to be sensible to the discrimination of semantically associated words. Another component found but not described in the literature for this type of task is the P2 component. Therefore, this study may increase the knowledge about the neurobiological basis and the behavioral functioning, especially regarding the semantic word processing. / Nas últimas décadas o interesse pela investigação do fenômeno da falsa-memória tem se ampliado. Na literatura ainda é escasso o número de estudos que investigam os componentes eletrofisiológicos subjacentes ao reconhecimento verdadeiro e ao reconhecimento falso, principalmente no que diz respeito a crianças e adolescentes com diagnóstico de autismo. O presente trabalho teve como objetivo analisar as diferenças comportamentais no desempenho da tarefa adaptada do paradigma de Roediger e McDermott nos dois grupos e verificar a presença de componentes eletrofisiológicos na fase de reconhecimento. Participaram do estudo 15 crianças/adolescentes, sendo 7 de grupo com diagnóstico de autismo (média 15 ±3,6) e 8 de grupo com desenvolvimento típico (média 10,7 ±2,5.). Resultados comportamentais mostram que não houve diferença significativa entre as taxas de acertos por reconhecimento da palavra-alvo, erro por falsas-pistas e erro por distratores. Ao contrário do que se esperava essa diferença também não foi observada no grupo de crianças com autismo, indicando assim que talvez não ocorra neste tipo de tarefa um processamento literal da informação. Análise dos dados eletrofisiológicos na fase de reconhecimento revelou o componente old/new (500-1000ms) que apresenta maior amplitude para reconhecimento verdadeiro em comparação ao reconhecimento falso. O interessante é verificar que esse componente foi observado tanto no grupo de desenvolvimento típico como no grupo com autismo. Além disso, foi encontrado componente P1 de menor amplitude para rejeição correta de falsas-pista em comparação aos outros tipos de acertos. Esse componente parece sensível a discriminação das palavras com associação semântica. Outro componente encontrado e que não é descrito na literatura para esse tipo de tarefa é o componente P2. Dessa forma, este estudo pode aumentar o conhecimento sobre as bases neurobiológicas e comportamentais do funcionamento no especialmente no que se refere ao processamento semântico de palavras.

Ce travail de thèse s’inscrit dans une approche dimensionnelle de la psychopathologie et son objectif est d’apporter de nouvelles connaissances au champ de recherche qui considère l’existence d’un continuum entre schizophrénie et trouble bipolaire ainsi qu’entre traits de personnalité et pathologies. Afin d’explorer ces continuums, nous avons étudié, grâce à la méthode des potentiels évoqués cognitifs et l’étude de certaines de leurs composantes (N400, LPC), les processus neurocognitifs sous-tendant l’intégration d’un contexte sémantique et sémantico-émotionnel dans la schizophrénie, le trouble bipolaire, les traits de personnalité schizotypique et les traits de personnalité hypomaniaque. Premièrement, nous avons montré, que les patients schizophrènes stabilisés et les patients bipolaires euthymiques présentent des patterns de modulation de la N400 différents lors de tâches impliquant l’intégration d’un contexte sémantique ou sémantico-émotionnel. Néanmoins, ces résultats en défaveur de l’existence d’un continuum entre schizophrénie et trouble bipolaire pourraient être la conséquence de l’absence de symptomatologie commune entre nos deux échantillons de patients. Deuxièmement, les résultats des études portant sur la population pathologique et ceux des études portant sur la population générale présentant des traits de personnalité semblent en faveur de l’existence d’un continuum entre population générale et pathologie. En effet, les personnes présentant des traits de personnalité hypomaniaque présentent des similitudes dans les atteintes des processus neurocognitifs sous-tendant l’intégration d’un contexte sémantique et sémantico-émotionnel avec les patients bipolaires, et les personnes présentant des traits de personnalité schizotypique présentent des similitudes dans les atteintes des processus neurocognitifs sous-tendant l’intégration d’un contexte sémantico-émotionnel avec les patients schizophrènes. L’ensemble de nos résultats associés à ceux de la littérature semblent en faveur d’une approche dimensionnelle de la psychopathologie bipolaire et schizophrénique où les symptômes, davantage que le diagnostic, doivent être envisagés comme le point central du continuum. / This work is part of a dimensional approach of the psychopathology. Its goal is to bring new knowledge to the field of research that considers the existence of a continuum between schizophrenia and bipolar disorder as well as between personality traits and pathologies. In order to explore these continuums, we have studied, thanks to event-related potential method and the study of N400 and LPC components, neurocognitive processes involved in the integration of semantic and semantico-emotional context in schizophrenia, bipolar disorder, schizotypal personality traits and hypomanic personality traits. We have first demonstrated that stabilized schizophrenic patients and euthymic bipolar patients have different patterns of the N400 modulation during tasks involving semantic and semantico-emotional integration. However, these results against the existence of a continuum between schizophrenia and bipolar disorder could be due to the lack of common symptoms in both samples. Secondly, the results of our studies dealing with clinical population and those dealing with general population with personality traits seem to be in favor to the existence of a continuum between general population and pathology. As a matter of fact individuals with hypomanic personality traits have similitude with bipolar patients in disturbance in neurocognitive processes involved in the integration of semantic and semantico-emotional context. Furthermore, individuals with schizotypal personality traits have common difficulties with schizophrenic patients in neurocognitive processes involved in semantico-emotional context integration. The results of our investigation, combined with those in the literature, are in favor of a dimensional approach of schizophrenic and bipolar psychopathology. And this approach is more about considering the symptoms as the central point of the continuum rather than the diagnostic.

Reward prediction errors are quantitative signed terms that express the difference between the value of an obtained outcome and the expected value that was placed on it prior to its receipt. Positive reward prediction errors constitute reward, negative reward prediction errors constitute punishment. Reward prediction errors have been shown to be powerful drivers of reinforcement learning in formal models and there is thus a strong reason to believe they are used in the brain. Isolating such neural signals stands to help elucidate how reinforcement learning is implemented in the brain, and may ultimately shed light on individual differences, psychopathologies of reward such as addiction and depression, and the apparently non-normative behaviour under risk described by behavioural economics. In the present thesis, I used the event related potential technique to isolate and study electrophysiological components whose behaviour resembled reward prediction errors. I demonstrated that a candidate component, “feedback related negativity”, occurring 250 to 350 ms after receipt of reward or punishment, showed such behaviour. A meta-analysis of the existing literature on this component, using a novel technique of “great grand averaging”, supported this view. The component showed marked asymmetries however, being more responsive to reward than punishment and more responsive to appetitive rather than aversive outcomes. I also used novel data-driven techniques to examine activity outside the temporal interval associated with the feedback related negativity. This revealed a later component responding solely to punishments incurred in a Pavlovian learning task. It also revealed numerous salience-encoding components which were sensitive to a prediction error’s size but not its sign.

Introdução: O P300 é um potencial evocado auditivo que ocorre aproximadamente 300 milissegundos (ms) após a apresentação do estímulo. Geralmente, é evocado ao se utilizar o paradigma tradicional, no qual são apresentados dois estímulos perceptivelmente diferentes: um estímulo frequente (85%) e um estímulo raro (15%). Os indivíduos são orientados a indicar, de alguma maneira, a quantidade de estímulos raros que perceberam durante a realização do exame. O P300 é considerado um potencial endógeno, pois ocorre devido a um evento cognitivo (decisão da ocorrência do estímulo raro). Contudo, alguns estudos mostraram que as características acústicas do estímulo podem interferir no potencial, evidenciando uma contribuição exógena ou sensorial para evocar a resposta. Essas implicações endógenas e exógenas para evocar o P300 ainda não foram totalmente definidas. A avaliação desses aspectos específicos pode ajudar a identificar os geradores desse potencial. Objetivo: verificar o efeito da contribuição endógena e exógena para obtenção do P300, utilizando paradigma tradicional e o paradigma de omissão. Métodos: participaram desse estudo 30 indivíduos jovens adultos, normo-ouvintes sem alteração neurológica ou psiquiátrica aparente. Os indivíduos foram avaliados com o paradigma tradicional (estímulo frequente: 800 Hz; estímulo raro 1200 Hz) e com o paradigma de omissão (estímulo frequente: 800 Hz; estímulo raro: ausência de som). Cada orelha foi avaliada separadamente por ambos os paradigmas na intensidade de 80 dBNPS. Foram apresentados 300 estímulos (45 raros) em cada estimulação. Para a obtenção do P300, foi utilizado o equipamento \"Neuroscan Stim2\" com 12 eletrodos ativos no escalpo, colocados nas seguintes posições: FPz, F4, Fz, F3, C4, Cz, C3, CP6, CP5, P4, Pz e P3. O maior pico após o complexo N1-P2-N2 foi considerado como P300. A amplitude foi medida considerando a linha de base do intervalo pré-estímulo, enquanto a latência foi medida no maior pico positivo. Nesse estudo, foi utilizada a Análise de Variância (ANOVA) com medidas repetidas. Foram realizados mapas topográficos do escalpo para ambas as estimulações. Resultados: para todos os 12 eletrodos analisados nesse estudo, a média da latência em milissegundos foi significantemente menor, e a média da amplitude foi significantemente maior para o paradigma tradicional quando comparado ao paradigma de omissão. Além disso, a morfologia da onda foi mais bem definida para o paradigma tradicional. Os mapas topográficos para ambos os paradigmas mostraram uma ativação mais generalizada e mais positiva na região centro-parietal, indicando que as mesmas áreas foram ativadas em ambos os paradigmas. Conclusão: o presente estudo demonstrou que o estímulo acústico, ausente no paradigma de omissão, influencia a latência, amplitude e morfologia da onda, evidenciando uma contribuição exógena/sensorial para obtenção do potencial / Introduction: The P300 is an auditory evoked potential that occurs approximately 300 ms after the stimulus presentation. It is usually elicited by a traditional paradigm in which two perceptually different stimuli are randomly presented with different proportions - one is frequent (85%) and the other is rare (15%). The tested individual is instructed to somehow indicate the amount of rare stimuli heard. According to the literature, P300 is considered an endogenous potential since it occurs in response to a cognitive event (i.e. decision of the occurrence or not of the rare stimulus). However, few studies have shown that the acoustic characteristics of the stimuli might influence the potential, evidencing some exogenous or sensorial contribution to the response formation. The implications that endogenous and exogenous contributions have to eliciting the P300 are not fully understood yet. The assessment of their specific roles would help to identify the P300 generators. Objective: To verify the effects of the endogenous and exogenous contribution to obtain/elicit the P300 using both the traditional and the omission paradigms. Methods: Thirty normal hearing young adults, without known neurological or psychiatric disorders, participated in this study. The individuals were assessed using P300 elicited by the traditional paradigm (frequent stimulus: 800 Hz; rare stimulus: 1200Hz) and by the omission paradigm (frequent stimulus: 800 Hz; rare stimulus: absence of sound). Both paradigms were presented to one ear at a time, at 80dBSPL, and 300 stimuli (45 rare) were presented in each stimulation. The \"Neuroscan Stim2\" was used to obtain the P300 with 12 active electrodes fixed at the following positions: FPz, F4, Fz, F3, C4, Cz, C3, CP6, CP5, P4, Pz e P3. The largest peak after the N1-P2-N2 complex was considered the P300. Its amplitude was measured considering the pre-stimulation response baseline, while its latency was measured at the most positive peak. The Analysis of Variance (ANOVA) with repeated measures was used in this study. Topographic maps from the scalp to both paradigms were also analyzed. Results: To all 12 electrodes positions analyzed in this study, the mean latency (ms) was significantly earlier and the mean amplitude (?V) was significantly larger for the traditional paradigm compared to the omission paradigm. Also, better wave morphology was obtained for the traditional paradigm. The topographic maps to both paradigms has shown more generalized and positive activation at the centro-parietal region, indicating that the same brain areas were involved in both paradigms. Conclusion: The current study has demonstrated that the acoustic stimulus, absent on the omission paradigm, have an impact on the wave formation in respect to its latency, amplitude and morphology, evidencing the influence of sensorial information to the P300

Like other animals, humans explore to learn about the world, and exploit what we have learned in order to maximize reward. The trade-off between exploration and exploitation is a widely-studied topic that cuts across multiple domains, including animal ecology, economics, and computer science. This work approaches the explore-exploit dilemma from the perspective of cognitive neuroscience. In particular, how are our decisions to explore or exploit represented computationally? And how is that representation implemented in the brain? Experiment 1 examined neural signals following outcomes in a risk-taking task. Explorations – defined as slower responses – were preceded by an enhancement of the P300, a component of the human event-related brain potential thought to reflect a phasic release of norepinephrine from locus coeruleus. Experiment 2 revealed that the same neural signal precedes feedback in a learning task called a two-armed bandit. There, a reinforcement learning model was used to classify responses as either exploitations or explorations; exploitations were driven by previous rewards, and explorations were not. Experiments 3 and 4 extended these results in three important ways. First, evidence is presented that the neural signal observed in Experiments 1 and 2 was driven not only by the upcoming decision, but also by the preceding decision (perhaps even more so). Second, Experiments 3 and 4 involved increasingly larger action spaces. Experiment 3 involved choosing from among either 4, 9, or 16 options. Experiment 4 involved searching for rewards in continuous two-dimensional map. In both experiments, the feedback-locked P300 was enhanced following exploration. Third, exploitation was the more common strategy in Experiments 1 and 2. Thus, it was unclear whether the exploration-related P300 enhancement observed there was due to exploration per se, to exploration rate, or to the fact that exploration was rare compared to exploitation. Experiment 3 partially address this by eliciting different rates of exploration; the exploration-related P300 effect correlated with rate of exploration. In Experiment 4, exploration was more common than exploitation (in contrast to Experiments 1–3); even so, exploration was followed by a P300 enhancement. Together, Experiments 1–4 suggest the presence of a general neural system related to exploration that operates across multiple task types (discrete to continuous), regardless of whether exploration or exploitation is the more common task strategy. The proposed purpose of this neural signal is to interrupt one mode of decision-making (exploration) in favour of another (exploitation). / Graduate

Cílem této diplomové práce je najít a popsat souvislost mezi fixací očí v emočně zabarveném stimulu, kterým je obrázek či video, a EEG signálu. K tomuto studiu je třeba vyvinout softwarové nástroje v prostředí Matlab k úpravě a zpracování dat získaných z eye trackeru a propojení s EEG signály pomocí nově vytvořených markerů. Na základě získaných znalostí o fixacích, jsou v prostředí BrainVision Analyzeru EEG data zpracovány a následně jsou segmentovány a průměrovány jako evokované potenciály pro jednotlivé stimuly (ERP a EfRP). Tato práce je vypracována ve spolupráci s Gipsa-lab v rámci výzkumného projektu.

Moderate-to-severe traumatic brain injury (M/S TBI) is a growing public health concern with significant impact on the cognitive functioning of survivors. Cognitive control and deficits in awareness have been linked to poor recovery and rehabilitation outcomes. One way to research cognitive control is through awareness of errors using electroencephalogram and event-related potentials (ERPs). Both the error-related negativity and the post-error positivity components of the ERP are linked to error awareness and cognitive control processes. Attentional capacity and levels of apathy influence error awareness in those with M/S TBI. There are strong links between awareness, attention, and apathy. However, limited research has examined the role of attention, awareness, and apathy using electrophysiological indices of error awareness to further understand cognitive control in a M/S TBI sample. The current study sought to elucidate the role of apathy in error awareness in those with M/S TBI. Participants included 75 neurologically-healthy controls (divided randomly into two control groups) and 24 individuals with M/S TBI. All participants completed self-report measures of mood, apathy, and executive functioning, as well as a brief neuropsychological battery to measure attention and cognitive ability. To measure awareness, participants completed the error awareness task (EAT), a modified Stroop go/no-go task. Participants signaled awareness of errors committed on the previous trial. The M/S TBI group decreased accuracy while improving or maintaining error awareness compared to controls over time. There were no significant between-group differences for ERN and Pe amplitudes. Levels of apathy in the M/S TBI group were included in three multiple regression analyses predicting proportion of unaware errors, ERN amplitude, and Pe amplitude. Apathy was predictive of error awareness, although not in the predicted direction. Major analyses were replicated using two distinct control groups to determine potential sample effects. Results showed consistent results comparing both control groups to a M/S TBI group. Findings show variable levels of awareness and accuracy over time for those with M/S TBI when compared to controls. Conclusions include varying levels of attention and awareness from the M/S TBI group over time, evidenced by improving awareness of errors when they are happening, but an inability to regulate performance sufficiently to improve accuracy. Levels of apathy are playing a role in error awareness, however, not in predicted directions. The study provides support for the role of attentional impairments in error awareness and encourages future studies to look for varying levels of performance within a given task when using populations linked to elevated levels of apathy and attentional deficits.