Earlier ages of alcohol initiation have been associated with an increased vulnerability for Alcohol Use Disorder and general risk taking behaviors beyond genetic influence. Reward processes, including reward anticipation (pleasure before receiving alcohol/general reward), reward learning (how quickly one pairs a stimulus with alcohol/general reward), and reward consummation (pleasure when receiving alcohol/general reward), have been implicated as potential mechanisms accounting for this vulnerability. However, no careful bio-behavioral research has been conducted on the effect of age of alcohol initiation on general and alcohol-related reward processes. Using Event Related Potentials (ERPs), the current study addressed this gap in a sample of 123 current alcohol drinkers. The Monetary Incentive Delay-General task and Monetary Incentive Delay-Alcohol task were administered to participants, in which reward learning (quickness of pairing the neutral cue or alcohol cue with monetary feedback), reward anticipation (activity to neutral cue or alcohol cue), and reward consummation (activity to monetary feedback) were examined. Electroencephalography was used to collect ERPs that index reward anticipation (P3) and reward consummation (P3 and Late Positive Potential) during these tasks. Earlier ages of alcohol initiation were associated with increased alcohol-related reward learning and decreased alcohol-related reward consummation (P3 and Late Positive Potential) beyond genetic and environmental covariates. There were no other significant relationships. These findings support and extend alcohol theories by showing that earlier ages of alcohol initiation may foster a greater sensitization in alcohol-specific reward-learning and more pronounced decreases in alcohol-related consummation. Although in need of direct testing, this might explain why earlier ages of alcohol initiation are associated with an increased vulnerability to Alcohol Use Disorder.

Background: Despite the so-called "generalised" nature of many epileptic seizures, patient specific spatio-temporal properties have been shown using imaging data at the macroscopic level of the cortex. Previous computational models have failed to account for spatial heterogeneities at the scale of the entire cortex. Furthermore, one of they key benefits of developing a model is the ability to easily test stimulation protocols. Previous studies of generalised spike-wave (the hallmark of absence epilepsy) have abstracted away from this.METHODSIn this work we develop a set of models of epileptic activity, one of which is at the scale of the entire cortex and incorporates anatomically relevant connectivity from human subjects. A similar model incorporating physiologically relevant thalamocortical circuitry is developed in order to test hypotheses regarding stimulation protocols.RESULTSWe show that the model can account for large-scale spatio-temporal dynamics similar to those seen in epileptic patients. We demonstrate, using the model of thalamocortical interaction, that such a modelling approach can be used for the evaluation of stimulation protocols which are shown to successfully abort the seizure prematurely.CONCLUSIONThis work highlights the importance of computational modelling to support existing data and to make specific predictions regarding testable hypotheses. For example, a stimulus given at the correct time with the correct amplitude will stop the seizure.

Un des enjeux majeurs de la Psychologie Cognitive est de décrire les grandes fonctions mentales, notamment chez l’humain. Du point de vue neuroscientifique, il s’agit de modéliser l’activité cérébrale pour en extraire les éléments et mécanismes spatio-temporels susceptibles d’être mis en correspondance avec les opérations cognitives. Le travail de cette thèse a consisté à définir et mettre en œuvre des stratégies originales permettant de confronter les modèles cognitifs existants à des données issues d’enregistrements neurophysiologiques chez l’humain. Dans une première étude nous avons démontré que la distinction entre les organisations classiques de la dénomination de dessin sériel-parallèle, doit être adressée au niveau des essais uniques et non sur la moyenne des signaux. Nous avons conçu et mené l’analyse des signaux SEEG de 15 patients pour montrer que l’organisation temporelle de la dénomination de dessin n’est pas, au sens strict, parallèle. Dans une deuxième étude nous avons combiné trois techniques d’enregistrements : SEEG, EEG et MEG pour clarifier l’organisation spatiale des sources d’activité neuronales. Nous avons établi la faisabilité de l’enregistrement sur un patient qui exécute une tâche de perception visuelle. Au delà des corrélations entre les signaux moyens des trois techniques, cette analyse a révélé des corrélations au niveau des essais uniques. À travers deux approches expérimentales, cette thèse propose de nombreux développements méthodologiques et conceptuels originaux et pertinents. Ces contributions ouvrent de nouvelles perspectives à partir desquelles les signaux neurophysiologiques pourront informer les théories des Neurosciences Cognitives. / A major issue in Cognitive Psychology is to describe human cognitive functions. From the Neuroscientific perceptive, measurements of brain activity are collected and processed in order to grasp, at their best resolution, the relevant spatio-temporal features of the signal that can be linked with cognitive operations. The work of this thesis consisted in designing and implementing strategies in order to overcome spatial and temporal limitations of signal processing procedures used to address cognitive issues. In a first study we demonstrated that the distinction between picture naming classical temporal organizations serial-parallel, should be addressed at the level of single trials and not on the averaged signals. We designed and conducted the analysis of SEEG signals from 5 patients to show that the temporal organization of picture naming involves a parallel processing architecture to a limited degree only. In a second study, we combined SEEG, EEG and MEG into a simultaneous trimodal recording session. A patient was presented with a visual stimulation paradigm while the three types of signals were simultaneously recorded. Averaged activities at the sensor level were shown to be consistent across the three techniques. More importantly a fine-grained coupling between the amplitudes of the three recording techniques is detected at the level of single evoked responses. This thesis proposes various relevant methodological and conceptual developments. It opens up several perspectives in which neurophysiological signals shall better inform Cognitive Neuroscientific theories.

Cognition is dynamic and complex, requiring specific sets of brain areas to cooperate for specific tasks. Neural synchronization is a proposed mechanism for transient functional integration of specific neural populations, enabling feature flexible binding and dynamic assignment of functional connectivity in the brain according to task demands. This thesis addresses the role of neural synchronization in selective attention and perceptual consciousness. The goals of this thesis are to test the hypothesis that synchronization between brain regions is relevant to network dynamics in selective attention and for perceptual organization, and to elucidate the function of synchronization in different frequency ranges. Using a selective visuospatial cuing paradigm it is shown that deploying attention to one visual hemifield yields transient long-distance gamma-band synchronization between contralateral visual cortex and other, widespread, brain regions. This is interpreted as a mechanism for establishing anticipatory biasing of communication in the cortex. Long-distance gamma synchrony, moreover, is periodically 'refreshed' at a theta rate, possibly serving to maintain this gamma network. While local alpha-band activity was found to be greater ipsilateral to the attended visual hemifield, alpha-band synchronization between primary visual cortex and higher visual areas was greater contralateral to attended locations. This suggests that local alpha synchrony is relevant for inhibition, while long-range alpha synchronization enacts functional coupling. The onset of a new conscious percept during binocular rivalry coincides with large-scale gamma-band synchronization which recurs at a theta rate. This suggests that gamma synchronization integrates features into a unified conscious percept while the theta cycle maintains that network. Using an audiovisual speech integration paradigm it is shown that large-scale gamma synchronization is greater when incongruence is detected between auditory and visual streams. This highlights an important distinction: neural synchronization reflects neural integration, not perceptual integration. Perceptual integration typically requires neural integration (feature binding), however, in this case detection of audiovisual mismatches requires cooperation within a distributed network, whereas audiovisual speech integration is largely accomplished in superior temporal cortex. These studies indicate that long-distance gamma synchronization establishes neural integration, the theta cycle maintains gamma synchronous networks, and local and long-range alpha synchrony reflect sustained inhibition and functional coupling mechanisms, respectively. / Medicine, Faculty of / Graduate

Neurocognitive models of speech comprehension generally outline either the spatial or temporal organisation of speech processing and rarely consider combining the two to provide a more complete model. Simultaneous EEG-fMRI recordings have the potential to link these domains, due to the complementary high spatial (fMRI) and temporal (EEG) sensitivities. Although the neural basis of speech comprehension has been investigated intensively during the past few decades there are still some important outstanding questions. For instance, there is considerable evidence from neuropsychology and other convergent sources that the anterior temporal lobe (ATL) should play an important role in accessing meaning. However, fMRI studies do not usually highlight this area, possibly because magnetic susceptibility artefacts cause severe signal loss within the ventral ATL (vATL). In this thesis EEG and fMRI were used to refine the spatial and temporal components of neurocognitive models of speech comprehension, and to attempt to provide a combined spatial and temporal model. Chapter 2 describes an EEG study that was conducted while participants listened to intelligible and unintelligible single words. A two-pass processing framework best explained the results, which showed comprehension to proceed in a somewhat hierarchical manner; however, top-down processes were involved during the early stages. These early processes were found to originate from the mid-superior temporal gyrus (STG) and inferior frontal gyrus (IFG), while the late processes were found within ATL and IFG regions. Chapter 3 compared two novel fMRI methods known to overcome signal loss within vATL: dual-echo and spin-echo fMRI. The results showed dual-echo fMRI outperformed spin-echo fMRI in vATL regions, as well as extra temporal regions. Chapter 4 harnessed the dual-echo method to investigate a speech comprehension task (sentences). Intelligibility related activation was found in bilateral STG, left vATL and left IFG. This is consistent with converging evidence implicating the vATL in semantic processing. Chapter 5 describes how simultaneous EEG-fMRI was used to investigate word comprehension. The results showed activity in superior temporal sulcus (STS), vATL and IFG. The temporal profile showed that these nodes were most active around 400 ms (specifically the anterior STS and vATL), while the vATL was consistently active across the whole epoch. Overall, these studies suggest that models of speech comprehension need to be updated to include the vATL region, as a way of accessing semantic meaning. Furthermore, the temporal evolution is best explained within a two-pass framework. The early top-down influence of vATL regions attempt to map speech-like sounds onto semantic representations. Successful mapping, and therefore comprehension, is achieved around 400 ms in the vATL and anterior STS.

The master´s thesis presents the problems of EEG biofeedback and its application to relax people. The first part discusses the properties of EEG signal , the requirements of the standard EEG and also distribusion signal into different frequency bands. The main essence of the work is the design and realization of Alfa Monitor – a device for relaxation , that for implamanting EEG biofeedback uses acoustic form and sensing of electrical activity of brain in the region of alpha waves. The second half of the work is t focused on circuit design, using integrated circuits with component values of relevant calculations . Further, it analyzes the practical implementation of alfa monitor. The last chapter is devoted to the testing the functionality of this device.

Im unter Ruhebedingungen abgeleiteten Elektroenzephalogramm (Ruhe-EEG) können Episoden niedergespannter EEG-Aktivität sowohl mit Schläfrigkeit, als auch mit geistiger Aktivität assoziiert sein. Aus diesem Grunde stellt niedergespannte EEG-Aktivität eine potentielle Fehlerquelle bei der Interpretation des Ruhe-EEGs dar. Wird niedergespannte EEG-Aktivität jedoch von für das Einschlafen charakteristischen, langsamen Augenbewegungen (Slow horizontal eye movements, SEM) begleitet, ist eine Assoziation mit geistiger Aktivität ausgeschlossen. Ziel dieser Dissertation ist die Untersuchung der Frage, ob niedergespannte EEG-Aktivität im Ruhe-EEG, welche von SEM begleitet wird (B1+), sich von solcher ohne begleitende SEM (B1-) hinsichtlich ihrer spektralen und räumlichen Zusammensetzung unterscheidet. Hierzu wurden 35 Ruhe-EEGs gesunder Probanden analysiert, welche jeweils mindestens 10s B1-, B1+ sowie 10s niedergespannter EEG-Aktivität während der Bearbeitung einer Kopfrechenaufgabe (calc) präsentierten. Unter Verwendung der Methode der standardized low resolution brain electromagnetic tomography (sLORETA) wurden für calc, B1- und B1+ die kortikalen Stromdichteverteilungen in vier verschiedenen, individuell angepassten Frequenzbändern berechnet. Die statistische Auswertung ergab signifikante Unterschiede zwischen B1- und B1+: Es zeigte bei B1- sowohl im Delta- als auch im Theta-Band eine geringere Aktivität im Bereich des Cingulums sowie benachbarten Teilen der Frontal-, Parietal- und Okzipiallappen. Zusätzlich zeigte sich eine erhöhte Aktivität im Frequenzbereich des Beta-Bandes in den Temporallappen für B1- verglichen mit B1+. Der Vergleich von calc mit B1+ erbrachte ähnliche Resultate. Die Befunde lassen eine Zugehörigkeit von B1- zu einem, verglichen mit B1+ höheren Vigilanzniveau vermuten und liefern Evidenz für die Einteilung niedergespannter Episoden im Ruhe-EEG in solche mit und ohne begleitende SEM.

This study examined quantitative EEGs of six individuals with chronic pain and compared them to an age- and gender-matched normative database of healthy control subjects in an attempt to discern whether a particular pattern of resting state EEG activity is associated with chronic pain. In the chronic pain group, significantly reduced absolute power was seen in delta and theta bandwidths at frontal sites in the eyes-closed condition. In the eyes-open condition, significantly reduced absolute power was seen in delta, theta, and alpha bandwidths at frontal, central, and temporal sites, and increased relative high beta power was seen in the parietal region. Reduced theta/high beta and delta/high beta ratios were seen in the parietal region. Quantitative EEG neuromarkers of chronic pain are suggested.

Repressors, defined as individuals possessing an increased cortical sensitivity to anxiety-provoking stimuli combined with the tendency to avoid such stimuli, may be differentiated from low- and high-anxious individuals. This study investigated behavioral performance, electrophysiological reactivity (EEG), and cardiovascular reactivity (heart rate, systolic and diastolic blood pressure) in three major coping style groups (repressors, low-anxious, and high-anxious) during low and high stressful conditions. Conditions were rest, cognitive stress (computerized Stroop Interference Task, with and without negative emotional stimuli), and physiological stress (cool water vs. ice cold water left hand immersions). Participants were 49 healthy, right handed university undergraduate women, chosen with Weinberger et al.'s (1979) criteria according to their differentially extreme scores on the Marlowe-Crowne Social Desirability Scale and the Spielberger Trait Anxiety Scale. Although mixed, findings supported the proposal that these three groups utilize differential attentional strategies and interpretive biases during both neutral and negative stimuli. In the word interference Stroop condition, reaction times (RTs) were longer for negative than neutral stimuli. Unexpected RT differences occurred in low and high error groups across the three coping styles. High error scoring repressors had longer RTs than low error/low-anxious; high-anxious/low error and high-anxious/high error groups did not differ. Repressors perceived the cold water as being less distressful and painful than the low- and high-anxious groups. No heart rate differences occurred. Diastolic and systolic blood pressure increased following cool and cold water immersion. Unexpectedly, the high-anxious group exhibited significantly lower diastolic blood pressure than the other groups, both at rest and following the stressors. EEG activation pattern differences were observed. During anticipation for cool immersion, in comparison to the high-anxious group, repressor and low-anxious groups showed less right parietal involvement suggestive of less arousal (Heller, 1993). During cool water immersion, frontal and parietal differences were observed across groups. During the Stroop Interference Task, repressors showed greater right frontal involvement than other groups. The data are most supportive of Eysenck and Derakshan's (1997) four-factor theory that proposes differential and attentional biases for these three groups. Suggestions for future research and practical applications in health fields are discussed. / Ph. D.

ADHS-Patienten im Alter von 8-12 Jahren wurde ein Ruhe-EEG von 10 Minuten jeweils mediziert sowie medikamentennüchtern abgeleitet und mittels des Vigilanzalgorithmus Leipzig von Hegerl und Hensch (2012) ausgewertet und den bei gesunden Kontrollkindern gleichen Alters gemessenen EEG-Frequenzen nach Auswertung durch die gleiche Methode gegenübergestellt. / Comparison of EEG-vigilance stages of children and youth from 8 to 12 years with ADHD (with and without medication)and healthy controls.