INTRODUÇÃO: O Acidente Vascular Cerebral Isquêmico (AVCI) é o evento mais freqüente dentre os AVCs, sendo caracterizado pela interrupção da irrigação sanguínea ao cérebro, a qual pode acarretar em lesão celular e alterações nas funções neurológicas. As manifestações clínicas desta doença podem incluir alterações das funções motoras, sensitivas, cognitivas, perceptivas, da linguagem entre outras. Sendo assim, é extremamente importante que sejam identificadas possíveis alterações nas vias auditivas, periférica e central, as quais podem prejudicar a qualidade de vida destes indivíduos. OBJETIVO: caracterizar os achados das avaliações comportamentais, eletroacústicas e eletrofisiológicas da audição em indivíduos destros com lesão isquêmica do hemisfério cerebral direito, bem como compará-los aos obtidos em indivíduos normais da mesma faixa etária. MÉTODOS: foram realizadas audiometria tonal, logoaudiometria, medidas de imitância acústica, potencial evocado auditivo de tronco encefálico (PEATE), potencial evocado auditivo de média latência (PEAML) e potencial cognitivo (P300) em 17 indivíduos com lesão do hemisfério direito (grupo pesquisa) e 25 normais (grupo controle), com idades entre 20 e 70 anos. RESULTADOS: Na análise dos dados qualitativos não foram encontradas alterações na avaliação comportamental da audição para os dois grupos. Ambos os grupos apresentaram alterações nos resultados do PEATE e do PEAML, sendo que houve diferença estatisticamente significante entre os grupos, para esses dois potenciais, nas quais o grupo pesquisa apresentou maior ocorrência de alterações. No PEATE a alteração mais freqüente foi do tipo tronco encefálico baixo, sendo que, entre os grupos, houve diferença estatisticamente significante, na qual o grupo pesquisa mostrou maior ocorrência dessa alteração. No PEAML a alteração predominante foi do tipo ambas (efeito orelha e efeito eletrodo ocorrendo concomitantemente) para o grupo pesquisa, e do tipo efeito eletrodo para o grupo controle. Na análise dos dados quantitativos (realizada apenas para os potenciais evocados auditivos) verificou-se, no PEATE, que ocorreu diferença estatisticamente significante entre os grupos com relação às latências das ondas III e V e interpicos I-III e I-V. Para o PEAML, a diferença estatisticamente significante entre os grupos ocorreu apenas para a latência da onda Na na posição C3/A1. Para o P300, ocorreu diferença entre os grupos com relação à latência da onda P300, sendo que o grupo pesquisa apresentou tempo médio de latência maior; além disso, houve uma tendência estatisticamente significante entre as orelhas direita e esquerda dentro do grupo pesquisa, mostrando aumento de latência da onda P300 na orelha direita. CONCLUSÃO: Indivíduos destros com lesão de hemisfério direito apresentaram limiares auditivos dentro da normalidade na avaliação comportamental da audição, entretanto, apresentaram resultados indicativos de déficit no sistema nervoso auditivo central, nas avaliações eletrofisiológicas da audição. Foram observados comprometimentos em tronco encefálico baixo, bem como nas regiões subcorticais e corticais. Dificuldades auditivas não foram percebidas pelos indivíduos, sugerindo que, provavelmente tal sinal possa estar relacionado à uma heminegligência auditiva. Tornam-se necessários mais estudos que avaliem a via auditiva central destes indivíduos para uma melhor caracterização dos achados eletrofisiológicos / INTRODUCTION: The ischemic cerebral stroke (ICS) is the most frequent event among cerebral strokes. It is characterized by the interruption of blood supply to the brain, which can lead to cell damage and alterations in neurological functions. The clinical manifestations of this disease may include alterations in motor, sensory, cognitive, perceptual and language functions among others. Therefore, the identification of possible alterations in both peripheral and central auditory pathways that may impair the quality of life of these individuals is extremely important. OBJECTIVE: To characterize the findings of behavioral, electrophysiological and electroacoustic hearing evaluations in right-handed individuals with right hemisphere ischemic lesion, and to compare such data to those obtained in normal individuals with the same age. METHODS: Pure tone audiometry, speech audiometry, acoustic immittance measures, brainstem auditory evoked potential (BAEP), Auditory Middle-Latency Response (AMLR) and cognitive potential (P300) were carried out in 17 subjects with right hemisphere lesions (research group) and 25 normal individuals (control group), aged between 20 and 70 years. RESULTS: No alterations were found on the qualitative data analysis of the hearing behavioral assessment of both groups. Both groups showed alterations in the BAEP and AMLR results, with statistically significant differences between groups for both potentials and a higher occurrence of alterations in the research group. The lower brainstem was the most frequent alteration type in the BAEP, and a statistically significant difference between groups was observed, with higher occurrence of such alteration in the research group. With regards the AMLR, the alteration predominantly observed was the Both type one (ear effect and electrode effect occurring concurrently) for the research group, and the electrode effect type one for the control group. In the analysis of quantitative data (performed only for the auditory evoked potentials), a statistically significant difference between groups was observed with respect to the BAEP latencies of waves III, V and interpeaks I-III and I-V. Regarding the AMLR measures, a statistically significant difference between groups was observed only for the Na wave latency in the C3/A1 position. For the P300, a difference between groups was observed, with higher mean latencies for the research group. In addition, there was a trend to statistically significant difference between right and left ears in the research group, which showed increased latency of P300 wave in the right ear. CONCLUSION: Right-handed individuals with right hemisphere lesion showed hearing thresholds within normal limits in the behavioral hearing assessment. However, they presented results indicative of central auditory nervous system deficits on the electrophysiological assessment of hearing. Alterations were observed in lower brainstem and in sub-cortical and cortical regions. Hearing difficulties were not perceived by these individuals, suggesting that this signal can probably be related to an auditory hemineglect. Further studies that evaluate the central auditory pathway of individuals with ICS are needed to better characterize the electrophysiological findings

L’objectif de cette thèse est d’étudier l’activation du système affectif médiée par le lexique orthographique au cours de la reconnaissance visuelle des mots. Plus précisément, nous avons étudié l’influence du voisinage orthographique émotionnel négatif et la sensibilité de l’amorçage orthographique à la valence négative de voisins plus fréquents dans une tâche de décision lexicale (TDL) combinée à un paradigme d’amorçage. Le recueil de mesures comportementales et électrophysiologiques (potentiels évoqués) nous a également permis d’évaluer la précocité de l’activation des composantes émotionnelles des voisins. Des mots neutres (e.g., FUSEAU, TOISON) ayant un seul voisin orthographique plus fréquent neutre (e.g., museau) ou négatif (e.g., poison) ont ainsi été présentés dans la TDL. Ils étaient précédés de leur voisin ou d’une amorce contrôle non alphabétique présenté pendant 66 ou 166 ms. Dans un premier temps, l’état émotionnel des participants a été contrôlé (Expériences 1-4). Dans un second temps, il a été manipulé a priori par une induction d’humeur triste (Expériences 5 et 7) ou déterminé a posteriori en considérant le niveau d’épuisement professionnel des participants (Expériences 7-8). Le traitement des mots fréquents neutres ou négatifs a été examiné en complément (Expérience 6). Les résultats montrent un effet inhibiteur du voisinage orthographique émotionnel négatif sur les temps de reconnaissance des mots cibles ainsi qu’un effet inhibiteur d’amorçage orthographique, accru par la durée de présentation des amorces. Trois composantes (P150, N200 et N400) constituent les corrélats électrophysiologiques de l’effet d’amorçage orthographique, sensibles à la valence négative des voisins et à la durée de présentation des amorces. Enfin, l’état émotionnel des individus modifie l’effet d’amorçage orthographique. Les résultats sont interprétés dans un modèle de type Activation Interactive de reconnaissance visuelle des mots adapté aux traitements affectifs. / The aim of this thesis was to study the activation of the affective system mediated by the orthographic lexicon during visual word recognition. More precisely, we have investigated the influence of the negative emotional orthographic neighbourhood and the sensitivity of orthographic priming to the negative valence of higher-frequency neighbours in the lexical decision task (LDT) combined with a priming paradigm. The recording of behavioural and electrophysiological (event-related brain potentials) measures provides also evidences on the early activation of affective components of the neighbours. Neutral words (e.g., FUSEAU [spindle], TOISON [fleece]) with one higher-frequency neighbour, that was either neutral (e.g., museau [muzzle]) or negative (e.g., poison), were presented in the LDT. They were preceded either by their neighbour or by a nonalphabetic control prime, presented 66 or 166 ms. Firstly, the emotional state of participants was controlled (Experiments 1-4). Secondly, it was manipulated a priori by a sad mood induction (Experiments 5 and 7) or determined a posteriori by considering the burnout level of participants (Experiments 7-8). The processing of negative or neutral frequent words have been also examined (Experiment 6). The results showed an inhibitory effect of negative emotional orthographic neighbourhood on target recognition time and an inhibitory effect of orthographic priming, increased by prime duration. Three components (P150, N200, and N400) were the electrophysiological correlates of orthographic priming effect, also depending on the negative valence of higher-frequency neighbours and prime duration. Finally, the emotional state of individuals modified the orthographic priming effect. The results are interpreted in an Interactive Activation model extended to affective processing.

Les troubles des tics, comme le syndrome de Gilles de la Tourette et le trouble de tics chroniques, sont des conditions neuropsychiatriques impliquant des tics moteurs et/ou phoniques. En plus de nombreuses comorbidités, les patients qui en sont atteints ont aussi des difficultés neuropsychologiques, notamment au niveau de l’inhibition et des fonctions motrices. La thérapie cognitivo-comportementale permet d’améliorer les tics et la condition générale de ces patients. Nous avons donc enregistré, durant une tâche de compatibilité stimulus-réponse, les potentiels évoqués cognitifs et les potentiels de latéralisation motrice (lateralized readiness potential; LRP) chez 20 patients atteints de trouble des tic avant et après une thérapie cognitivo-comportementale, et chez 20 participants contrôles. Chez les patients atteints de trouble des tics, nos résultats ont révélé une apparition plus tardive de l’amorce du LRP moyenné par rapport au stimulus, une amplitude plus élevée du LRP moyenné par rapport à la réponse, et une suractivation frontale liée aux processus d’inhibition. Suite à la thérapie, le retard au niveau de la latence de l’amorce du LRP moyenné par rapport à la réponse est comblé et l’amplitude du LRP moyenné par rapport à la réponse est normalisée, mais pas la suractivation frontale liée à l’inhibition. Cela suggère donc que la thérapie induit une modification des processus prémoteurs de sélection et de préparation de la réponse, ainsi que des processus d’exécution motrice, mais n’altère pas la suractivation frontale reliée aux fonctions inhibitrices. Étant donnés ces résultats, nous suggérons que la thérapie cognitivo-comportementale induit une modification du fonctionnement des aires motrices du cerveau. / Gilles de la Tourette syndrome and chronic tic disorder are two neuropsychiatric condition involving motor and/or phonic tics. In the DSM, these two conditions are characterized as “tic disorders”. Patients with such diagnoses face numerous comorbidities, and also show multiple neuropsychological impairments, especially concerning inhibition and motor processing. Tic symptoms, as well as general condition, can be improved with a cognitive-behavioural therapy (CBT). To this end, we recorded, during a stimulus-response compatibility task, event-related potentials and lateralized readiness potentials in 20 patients with tic disorder and 20 healthy controls. Patients and controls were paired on age, sex and hand dominance. Our result revealed a delay in stimulus-locked lateralized readiness potential (LRP) onset latency, higher response-locked LRP peak amplitude and a frontal overactivation related to stimulus inhibition in GTS and CTD patients. Following CBT, stimulus-locked LRP onset latency and response-locked LRP peak amplitude were normalized, but the frontal overactivation related to inhibition processing remained unchanged. These results suggest that CBT induces a modification of pre-motor processes such as response selection and preparation, as well as motor processes like response execution, but does not affect cortical activation related to stimulus inhibition. Since we found a reduction in tic symptoms, as well as a normalization of stimulus-locked LRP onset latency and response-locked LRP peak amplitude, and because LRPs are partly generated by the supplementary motor area, we suggest that CBT leads to a modification of this structure’s functioning.

Les tics affectent 1% des individus et sont associés avec une diminution de la qualité de vie. L’importante hétérogénéité phénoménologique retrouvée chez ceux-ci représente un obstacle majeur pour l’évaluation et le traitement de ces symptômes, et explique potentiellement la présence de données neurobiologiques contradictoires. Certaines variables rarement contrôlées, comme la complexité des tics et la demande motrice des tâches pourraient expliquer l’hétérogénéité de ces résultats. Une meilleure compréhension des processus cognitifs affectés pourrait être atteinte par l’étude de la chronométrie des événements cérébraux. Ainsi, notre objectif était d’évaluer l’impact de la complexité des tics et du type de réponse sur les potentiels électrocorticaux liés à l’inhibition, à l’attention et à la mémoire de patients tics. Nous avons comparé 12 patients présentant des tics simples avec 12 patients atteints de tics complexes, qui furent appariés à 15 participants contrôles sains. Deux tâches oddball furent accomplies, dont l’une exigeait une réponse motrice et l’autre une réponse non-motrice (compter le nombre de stimuli). Durant ces tâches, nous avons enregistré des composantes électrocorticales indexant des processus d’attention (P200), d’inhibition (N200) et de mémoire (P300). Pour la tâche non-motrice, nos résultats révélèrent une N200 plus ample chez les deux groupes de patients tics et une P300 réduite seulement chez ceux avec des tics simples. Quant à la tâche motrice, les deux groupes de patients tics présentaient une P300 réduite. Selon nos résultats, la complexité des tics et la demande motrice des tâches peuvent affecter les mécanismes neuronaux sous-tendant les différentes étapes du traitement de l’information. / Tic disorders affect up to 1% of individuals worldwide and are associated with social stigma. A major obstacle to these disorders’ evaluation and treatment is the large heterogeneity of phenotypes, which could explain the important number of conflicting neurobiological data. Certain variables, like tic complexity and tasks’ cognitive demand, could explain these heterogeneous results. We propose that a better understanding of cognitive impairments often seen in tic disorders could be obtained by studying the chronometry of electrocortical activity underlying inhibition, attention, memory and motor processes. Our aim was to evaluate the impact of tic complexity as well as task response demand on tic patients’ electrocortical profiles. Thus, we compared 12 patients exhibiting simple tics to 12 patients showing complex tics, and matched them to 15 healthy control participants. All participants performed two Oddball tasks in which one required a motor response (button press) and the other a non-motor response (counting). During both tasks, electrophysiological components were recorded, serving as indices of processes underlying attention (P200), inhibition (N200) and memory (P300). Our results revealed that for the non-motor task, both groups of tics patients had an enhanced N200, while only those with simple tics showed a reduced P300. For the motor task, both groups of tics patients exhibited a decreased P300. According to our results, both tic complexity and motor demand can affect neural mechanisms of the processing stream. Conflicting results found in previous studies might have been confounded by tic complexity as well as task motor requirements.

In this dissertation the effects of variations in stimulus properties and CTOA, in auditory attention tasks were explored using recently developed approaches to EEG analysis including LIMO. The last experiment was structured using information theory, designing an effective experiment. Four studies were carried out using a number parity decision task, that employed different combinations of cueing Tone (T), Novel (N) and the Goal (G) stimuli. In the first EEG study, contrary to previous findings (Polich 2002, 2007) in control participants, no correlation between the time of a novel condition to the next novel condition and P300 amplitude was found. Therefore single trial across-subject averaging of participants’ data revealed significant correlations (r > .3) of stimulus properties (such as probability, frequency, amplitude and duration) on P300, and even r > .5 was found when N was an environmental sound in schizophrenic patients. In the second EEG study, simultaneously with fMRI recordings, the participants that showed significant behavioural distraction evoked brain activations and differences in both hemispheres (similar to Corbetta, 2002, 2008) while the participants, as a whole, produced significant activations mainly in left cortical and subcortical regions. A context analysis was run in distracted participants contrasting the trials immediately prior to the G trials, resulting in different prefrontal activations, which was consistent with studies of prefrontal control of visual attention (Koechlin 2003, 2007). In the third EEG study, the distractor noise type was manipulated (white vs environmental sounds) as well as presence or absence of scanner background noise in a blocked design. Results showed consistent P300, MMN and RON due to environmental noise. In addition, using time constants found in MEG results (Lu, Williamson & Kaufman, 1992) and adding the CTOA to the analysis, an information theory framework was calculated. After the simulation of the information of the experiment, a saddle indentation in the curve of the information measure based on the states of the incoming signal at around 300 ms CTOA was found. This saddle indentation was evident in more than 60 novel trials. In the fourth study, the CTOA and stimulus properties were manipulated in a parametric experiment. Based on the three studies, reducing complexity if the task (first study), using more than 60 stimuli in the novel conditions (third study). The CTOA randomly varying between 250 ms or 500 ms. Thirty-eight ANCOVA with 2 categorical and 1 continuous regressors were conducted and determined which time and channels elicited reliably signatures (p <.05) in the whole participants at short CTOA. Results revealed differences for the waveforms of current condition by depending on which condition appeared previously as well in terms of frequency and duration in scalp frontal electrodes (such as the second study). These results were interpreted as a consequence of switching between modes of attention and alerting states which resulted in the activation of frontal areas. Moreover, contextual analyses showed that systematic manipulation of stimulus properties allowed the visualization of the relationships between CTOA, executive function and orienting of attention.

The purpose of this research was to explore the effects of small monetary or economic gains and/or losses on choice behavior through the use of a computerized game and to determine gain/loss ratio differences using both behavioral and electrophysiological measures. Participants (N=53) played the game in several 36 minute sessions. These sessions operated with concurrent variable-interval schedules for both rewards and penalties. Previously, asymmetrical effects of gains and losses have been identified through cognitive studies, primarily due to the work of nobel laureates Daniel Kahneman and Amos Tversky (1979). They found that the effect of a loss is twice (i.e., 2:1) that of a gain. Similar results have been observed in the behavioral laboratory as exemplified by the research of Rasmussen and Newland (2008), who found a 3:1 ratio for the effect of losses versus gains. The asymmetry of gains and losses was estimated behaviorally and through event-related brain potentials (ERPs) and the cognitive (Kahneman and Tversky) and behavioral (Rasmussen and Newland) discrepancy elucidated. In the game, the player moves an animated submarine around sea rocks to collect yellow coins and other treasures on the sea floor. Upon collecting a coin, one of three things can happen: The player triggers a penalty (loss), the player triggers a payoff (gain), or there is no change. The behavioral measures consisted in counting the number of clicks, reinforces, and punishers and then determining ratio differences between punished (loss) and no punished condition (gain) conditions. The obtained gain/loss ratio corresponded to an asymmetry of 2:1. Similarly ratio differences were found between male and female, virtual money and cash, risk averse versus risk seeking, and generosity versus profit behavior. Also, no ratio difference was found when players receive information about other player's performances in the game (players with information versus players without information). In electroencephalographic (EEG) studies, visual evoked potentials (VEPs) and ERPs components (e.g., P300) were examined. I found increased ERP amplitudes for the losses in relation to the gains that corresponded to the calculated behavioral asymmetry of 2:1. A correlational strategy was adopted that sought to identify neural correlates of choice consistent with cognitive and behavioral approaches. In addition, electro cortical ratio differences were observed between different sets of electrodes that corresponded to the front, middle, and back sections of the brain; differences between sessions, risk averse and risk seeking behavior and sessions with concurrent visual and auditory stimuli and only visual were also estimated.

人們對於錯誤訊息處理經由自我覺察或外在回饋之管道，可藉由事件關聯電位分別測得ERN (error-related negativity) 及FRN (feedback-related negativity)。過去研究曾指出雙側作業(Flanker task)中錯誤所引發的ERN會受到以圖片呈現的短期情緒所調節，然而對於回饋誘發的FRN與個體情緒調節的關係則未曾被探討過。過去FRN的研究認為唯有當受試者所進行的作業為增強學習作業時，受試者對於回饋結果的預期狀態才能反映於FRN的反應強度。本研究利用兩個實驗分別採用非增強學習作業及增強學習作業，其中並以IAPS情緒圖片進行短期情緒的引發，在受試者於實驗中對其反應結果的不同預期狀態，探測受試者FRN受短期情緒調節的效果。 實驗一利用非增強學習作業，結果顯示FRN的強度可以反映受試者對於回饋結果的預期狀態，其中以非預期時FRN的強度為最大，預期時FRN的強度為最小；另外，正向情緒圖片對於FRN具有調節效果，正向情緒下FRN反應強度小於中性以及負向情緒下FRN反應強度。實驗二利用增強學習作業，前述的FRN強度反映受試者對回饋結果的預期效果，只有在實驗前半段的嘗試次中被觀測到，此效果未見於全部嘗試次納入分析；另外，實驗二中沒有觀察到情緒對於FRN的調節效果。 綜合而言，本研究發現受試者唯有持續處於學習的情形下，FRN才能反映受試者對於回饋結果的預期狀態，情緒對FRN的調節效果也僅於此情況下才能被觀測到。 / Error-related information in human can be processed via self-awareness and/or feedback given externally, which are measurable by the use of event-related potential (ERP) and termed error-related negativity (ERN) and feedback-related negativity (FRN) respectively. Previous studies showed that short-term affective stimuli would modulate the magnitude of ERN elicited by Flanker task. However, such modulation effect has not been tested on FRN. Furthermore, the magnitude of FRN is indicated to be related to the expectancy states toward feedback when the subject is undergoing a reinforcement learning task. Present study, thus, was designed to test the affective modulation effect on FRN in two separate tasks. In which, emotional pictures adopted from IAPS were used as the short-term affective stimuli, and different expectancy states in both non-reinforcement learning task (Experiment1) and reinforcement learning task (Experiment 2) were manipulated. In the results of Experiment 1, the magnitude of FRN was larger under the unexpected condition in comparing to the expected one. Modulation effect of short-term affective stimuli on FRN was obtained when positive emotion pictures were presented in non-reinforcement learning task, which FRN amplitude was significantly smaller in comparing to those measured after the presentation of neutral and negative pictures. In the results of Experiment 2, FRN elicited in the unexpected condition was only obtained from analyzing the dada collected in the first half of trails. Such effect was not confirmed when the data from all trials were analyzed. A lack of modulation effect of short-term affective stimuli on FRN appeared in Experiment 2. In conclusion, it is indicated that the expectancy depended FRN is most apparent when the subject is undergoing a continuous learning-demanded process. Meanwhile, short-term affective stimuli can modulate such FRN.

研究目的 失眠的過度激發假說是目前最廣為接受的失眠病因之一，失眠者通常可觀察到具有身心過度激發的狀態，其中認知神經過度激發假說更由中樞神經的角度探討失眠者的過度激發現象，且已有許多證據支持此觀點。然而過度激發因素在失眠病程上的影響仍不明確，不論在前置因子或是持續因子的層面，激發因素皆經常被提及與討論。本研究以未失眠但具有高睡眠脆弱特質之族群作為研究對象，企圖模擬失眠者在失眠初發之前的狀態，另加入睡前及早晨的自主神經系統與主觀激發狀態之測量，比較其與低睡眠脆弱特質組在有無壓力誘發狀態下，兩組的睡眠中訊息處理程度、睡前及早晨的自主神經系統激發程度與主觀激發狀態，藉以了解（1）壓力是否會引發個體進入較高的主、客觀激發狀態；(2)睡眠脆弱特質在不同的激發程度下，是否會對於個體的睡前、睡眠中及早晨的激發程度造成影響，以初步推論激發狀態因素在失眠病程中所扮演之角色。 方法 以壓力下失眠反應量表（Ford Insomnia Response to Stress Test, FIRST）區分出高睡眠脆弱特質組（HV）13位（6男、7女）、低睡眠脆弱特質組（LV）14位（6男、8女），年齡為19-32歲之健康成人。每位受試者均需在睡眠實驗室進行3個夜晚之夜間睡眠記錄，包含第一晚的PSG測量以排除個案有其他睡眠疾患，並讓受試者習慣實驗環境；第二晚及第三晚則交互平衡操弄基礎情境或壓力情境，在壓力情境下，受試者被告知將進行即席演講，需在睡前抽出演講題目，並於隔天早晨喚醒後10分鐘內發表一篇內容充實、呼應主題之演說，隨後測量心跳變異率（heart rate variability，HRV）、平均心跳間距（r-r interval，RRI）、主觀身心激發狀態（Pre sleep arousal scale，PSAS）等主客觀激發程度，入睡後進行整夜的ERP（事件相關電位[Event-related potential，ERP]）測量，誘發ERPs之實驗流程以oddball典範為主，並於早晨起床後再次進行HRV、RRI及PSAS之測量。 結果 以2（組別）x 2（情境）之混和設計二因子變異數分析比較各組在不同情境下的主客觀激發程度指標是否有所不同。結果顯示壓力確實能引發受試者進入較高的主客觀激發狀態，包含睡前及早晨有較快的平均心跳速率、較高的主觀身心激發程度，而在NREM睡眠中可發現HV在有壓力的情境下，對外界的訊息處理程度顯著較LV組增加，包含較快的N1與較慢的N350出現，但HV在壓力下亦有較快的P2與較強的P900，顯示對外界訊息的抑制功能上升，且隨著睡眠更深，進入慢波睡眠時，P2及P900亦顯著較LV強，表現出更多的抑制外界訊息能力。 結論 本研究探討睡眠脆弱特質在不同激發狀態下對於睡眠的影響，結果顯示壓力能引發個體較高的激發狀態，然而在未失眠族群中，高睡眠脆弱特質對於認知激發狀態下的睡眠中訊息處理程度雖有提高，但可發現高睡眠脆弱特質組亦有較高的抑制外界訊息能力，而不致於使得激發狀態過度影響其睡眠，此結果部分支持失眠的認知神經過度激發假說，過度激發因素可能在持續因子的部分影響性較大，造成個體產生對睡眠的抱怨。另一方面，本研究結果亦彰顯失眠的高危險群的及早介入預防之重要性。 / Introduction: Conditioned hyperarousal has been theorized to be a major etiological factor in chronic insomnia patients. It has been suggested that insomniacs showed more arousal than non-insomniacs in many psychological and physiological measures, including enhanced information processing during sleep as measured by NREM ERPs. However, the role of hyperarousal on the course of development of insomnia remained unclear, it has been considered as a predisposing trait and/or perpetuating factor in the cause of insomnia. The present study compared arousal levels around sleep onset, during sleep and in the morning between non-insomniac individuals with low and high vulnerability to stress-related sleep disturbance, as high vulnerable individuals were proposed to be predisposed to chronic insomnia. The objectives of the study are therefore to investigate: 1) the effect of an acute stressor on arousal level prior, after, and during sleep, and 2) the differences in stress reactivity between individual with high and low vulnerability to stress-related sleep disturbances. Method: Fourteen healthy individuals scoring low (LV) and thirteen healthy individuals scoring high (HV) on the Ford Insomnia Response to Stress Test (FIRST) were studied. All subjects had to sleep in the lab for three nights: a screening/ adaptation night, then a baseline night and a stress night. The sequences of the later two nights were counterbalanced across subjects. During the stress night, subjects were informed that they would be required to give a speech immediately after waking up. Heart rate variability (HRV), r-r interval (RRI) of EKG and subjective arousal level (Pre sleep arousal scale, [PSAS]) was accessed before lights off and in the morning. Then sleep ERP was recorded during the night. An odd-ball paradigm was conducted to evoke ERPs throughout the night. Result: Mixed two-way ANOVAs were used to compare the differences between vulnerabilities and conditions. Both HV ans LV showed higher subjective arousal level and smaller RRI under the stress condition than the baseline condition. During NREM sleep, HV showed increased information processing under stress condition than LV as shown by faster N1, slower N350. Also, HV showed increased inhibition under stress condition than LV, with faster P2 and higher P900. Stronger P2 and P900 were also observed in HV when reached slow-wave sleep stage, comparing to LV. Conclusion: Both groups showed more arousal under stress condition than baseline condition, indicating an acute stress can lead to a higher arousal level. Moreover, high vulnerable individuals showed increased information processing during NREM sleep than low vulnerable individuals, but also showed more inhibition to prevent sleep from being disturbed by external stimulus. The results suggest that increased information processing in reacting to stress may be a predisposing trait for sleep disturbances. However, sleep may be protected by a compensatory inhibitory process in those who have not developed a long-term insomnia.

L'être humain est pourvu des multiples canaux sensoriels par lesquels il appréhende le monde. Un critère fondamental à notre adaptation est notre capacité à établir des relations entre les différentes informations que nos sens perçoivent. Cette capacité est notamment cruciale dans nos interactions sociales puisque nous devons constamment intégrer en une représentation unifiée les informations visuelles (telles que les visages), auditives (telles que les voix) et verbales (telles que le discours ou le nom) afin de pouvoir identifier nos interlocuteurs. Sachant que le traitement des principales informations qui nous permettent d'identifier les personnes (visages, voix et nom de famille) est sous-tendu par l'activation de régions cérébrales spécifiques et distinctes les unes des autres, la question qui se pose est de savoir comment le cerveau opère pour créer une représentation unifiée des personnes que nous connaissons. Dans la première partie de cette thèse, nous passerons en revue différentes études qui ont tenté de cerner les régions cérébrales impliquées dans le traitement (perception et reconnaissance) de chaque type d'information. Le premier chapitre sera consacré aux corrélats cérébraux du traitement des visages, le second à ceux impliqués dans le traitement des noms propres, le troisième à ceux impliqués dans le traitement des voix. Ces processus seront chaque fois abordés sous l'angle de la neuropsychologie cognitive, de l'imagerie cérébrale fonctionnelle et de l'électrophysiologie. Un quatrième chapitre théorique sera consacré à l'étude des processus associatifs entre ces trois types d'informations, et nous verrons que rares sont les études qui ont directement examiné les activités cérébrales spécifiques à la récupération d'associations entre informations relatives à l'identité des personnes. L'approche expérimentale sera abordée dans la seconde partie de cette thèse. Les quatre études décrites dans cette partie se basent sur les résultats de l'étude de Campanella et al. (2001) qui, par PET-scan, ont examiné les régions cérébrales activées par la récupération d'associations entre visages et noms propres. Utilisant la méthode soustractive, consistant en la soustraction de deux conditions unimodales d'une condition bimodale, ces auteurs ont montré une activation d'un réseau d'aires cérébrales latéralisé dans l'hémisphère gauche et incluant notamment le lobule pariétal inférieur, interprété comme étant une région de convergence multimodale où s'opère l'intégration des différentes informations perçues par les sujets. La méthode soustractive sera utilisée dans toutes les expériences décrites dans cette section. La première étude de cette thèse, utilisant la même méthodologie appliquée à la méthode électrophysiologique des potentiels évoqués, aura pour but d'examiner le décours temporel des activités observées par Campanella et al. (2001). La seconde étude en potentiels évoqués aura pour but d'examiner si les activités observées dans les deux études pré-citées sont spécifiques aux processus associatifs entre visages et noms propres, ou s'ils reflètent des processus plus généraux permettant de lier tout objet visuel à son nom. Les études 3 et 4 viseront quant à elles à définir si le lobule pariétal inférieur gauche est impliqué dans l'intégration de stimulations exclusivement visuelles, ou si il est impliqué dans le « binding » de tout type d'information relative aux personnes, quelle que soit les modalités de présentation. Dans ce cadre, l'étude 3 examinera les corrélats cérébraux impliqués dans la récupération d'associations entre visages et voix. L'étude 4 examinera cette question au moyen de l'imagerie par résonance magnétique fonctionnelle. La dernière partie de cette thèse sera consacrée à l'interprétation de l'ensemble des résultats des 4 expériences décrites précédemment. L'accent y sera mis sur la latence d'apparition des ondes spécifiques aux conditions associatives, apparaissant en même temps que les activités propres au traitement de chaque type d'information, ainsi que sur le rôle du gyrus pariétal inférieur gauche dans l'intégration des représentations des différents attributs par lesquels nous identifions les personnes.

In reading, word frequency is commonly regarded as the major bottom-up determinant for the speed of lexical access. Moreover, language processing depends on top-down information, such as the predictability of a word from a previous context. Yet, however, the exact role of top-down predictions in visual word recognition is poorly understood: They may rapidly affect lexical processes, or alternatively, influence only late post-lexical stages. To add evidence about the nature of top-down processes and their relation to bottom-up information in the timeline of word recognition, we examined influences of frequency and predictability on event-related potentials (ERPs) in several sentence reading studies. The results were related to eye movements from natural reading as well as to models of word recognition. As a first and major finding, interactions of frequency and predictability on ERP amplitudes consistently revealed top-down influences on lexical levels of word processing (Chapters 2 and 4). Second, frequency and predictability mediated relations between N400 amplitudes and fixation durations, pointing to their sensitivity to a common stage of word recognition; further, larger N400 amplitudes entailed longer fixation durations on the next word, a result providing evidence for ongoing processing beyond a fixation (Chapter 3). Third, influences of presentation rate on ERP frequency and predictability effects demonstrated that the time available for word processing critically co-determines the course of bottom-up and top-down influences (Chapter 4). Fourth, at a near-normal reading speed, an early predictability effect suggested the rapid comparison of top-down hypotheses with the actual visual input (Chapter 5). The present results are compatible with interactive models of word recognition assuming that early lexical processes depend on the concerted impact of bottom-up and top-down information. We offered a framework that reconciles the findings on a timeline of word recognition taking into account influences of frequency, predictability, and presentation rate (Chapter 4). / Wortfrequenz wird in der Leseforschung als wesentliche Bottom-up Determinante für die Geschwindigkeit des lexikalischen Zugriffs betrachtet. Darüber hinaus spielen Top-down Informationen, wie die kontextbasierte Wortvorhersagbarkeit, in der Sprachverarbeitung eine wichtige Rolle. Bislang ist die exakte Bedeutung von Top-down Vorhersagen in der visuellen Worterkennung jedoch unzureichend verstanden: Es herrscht Uneinigkeit darüber, ob ausschließlich späte post-lexikalische, oder auch frühe lexikalische Verarbeitungsstufen durch Vorhersagbarkeit beeinflusst werden. Um ein besseres Verständnis von Top-down Prozessen und deren Zusammenhänge mit Bottom-up Informationen in der Worterkennung zu gewährleisten, wurden in der vorliegenden Arbeit Einflüsse von Frequenz und Vorhersagbarkeit auf ereigniskorrelierte Potentiale (EKPs) untersucht. Die Ergebnisse aus mehreren Satzlesestudien wurden mit Blickbewegungen beim natürlichen Lesen sowie mit Modellen der Worterkennung in Beziehung gesetzt. Als primärer Befund zeigten sich in EKP Amplituden konsistent Interaktionen zwischen Frequenz und Vorhersagbarkeit. Die Ergebnisse deuten auf Top-down Einflüsse während lexikalischer Wortverarbeitungsstufen hin (Kapitel 2 und 4). Zweitens mediierten Frequenz und Vorhersagbarkeit Zusammenhänge zwischen N400 Amplituden und Fixationsdauern; die Modulation beider abhängigen Maße lässt auf eine gemeinsame Wortverarbeitungsstufe schließen. Desweiteren signalisierten längere Fixationsdauern nach erhöhten N400 Amplituden das Andauern der Wortverarbeitung über die Dauer einer Fixation hinaus (Kapitel 3). Drittens zeigten sich Einflüsse der Präsentationsrate auf Frequenz- und Vorhersagbarkeitseffekte in EKPs. Der Verlauf von Bottom-up und Top-down Prozessen wird demnach entscheidend durch die zur Wortverarbeitung verfügbaren Zeit mitbestimmt (Kapitel 4). Viertens deutete ein früher Vorhersagbarkeitseffekt bei einer leseähnlichen Präsentationsgeschwindigkeit auf den schnellen Abgleich von Top-down Vorhersagen mit dem tatsächlichen visuellen Input hin (Kapitel 5). Die Ergebnisse sind mit interaktiven Modellen der Worterkennung vereinbar, nach welchen Bottom-up und Top-down Informationen gemeinsam frühe lexikalische Verarbeitungsstufen beeinflussen. Unter Berücksichtigung der Effekte von Frequenz, Vorhersagbarkeit und Präsentationsgeschwindigkeit wird ein Modell vorgeschlagen, das die vorliegenden Befunde zusammenführt (Kapitel 4).