Whilst studies on rhythm-keeping and error-related negativity have been conducted, previous studies have given participants auditory or visual cues to indicate the rhythm they are meant to be maintaining. In this electroencephalography study, a novel experiment called the Human Metronome Task was introduced, using healthy university students as participants. The Human Metronome Task tested the participants by having them tap in synchrony with a beat, and then having the beat be removed, with the participants still being supposed to maintain the same beat with their taps, now without any auditory or visual aids. The purpose was to see if deviations in unassisted rhythm keeping are sufficient to elicit error-related negativity. When comparing different deviations of the tap-timing of each participant to their average tap-timing, no significant differences in electroencephalography amplitude were found. It was concluded that the Human Metronome Task is unable to elicit error-related negativity in participants. It seems plausible that this is due to the ambiguity of whether responses are erroneous or accurate. Thus, it seems as if it is necessary for more indications of whether a response is erroneous or not for the elicitation of error-related negativity than was present in the Human Metronome Task.

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Reward expectation and spatial attention both exert powerful control over behaviour and modulate neural activity. The experiments in this thesis aimed to chart the dynamics of reward expectation effects across the time course of information processing and examine the relationship between reward and attention. Experiments 3.1 and 3.2 parametrically manipulated reward magnitude in the presence or absence of attention and demonstrated reward could influence reaction time (RT) under conditions of time pressure. Experiments 4.1 and 4.2 independently varied reward and spatial probabilities and illustrated independent and interactive effects of reward and attention at late stages of cognitive processing (the P300 potential), as well as modulation of detection sensitivity (d') by reward under conditions of uncertainty when reward was able to work through feature-based attention. The experiment of Chapter 5 cued reward and attention trial by trial and showed under these conditions, not only could reward influence late stages of information processing, but expectation of reward reduced peak latency of the visual N1 potential. Reward and attention also modulated motor preparation with both independent and interactive effects. The experiment of Chapter 6 examined the dynamics of reward association with task-relevant targets and irrelevant distracters during visual search and demonstrated that task-irrelevant but motivationally-salient distracter items could capture attentional resources away from the target, guided by endogenous reward association alone. The experiments of this thesis demonstrated the ability of reward expectation to modulate both behaviour and multiple stages of information processing, with effects predominantly independent from those of attention. Reward could influence processing from early visual analysis and target detection stages. Interaction between the two systems occurred at late processing stages, whereby reward and attentional information may have been integrated to provide a cohesive representation of the stimulus given the current environmental conditions.

Les commotions cérébrales d’origine sportive sont fréquentes chez les athlètes professionnels et semblent l’être tout autant chez les jeunes sportifs. Chez l’adulte, les symptômes se résorbent dans la majorité des cas assez rapidement (7-10 jours), mais la récupération peut s’avérer différente chez les jeunes. Plusieurs études utilisant les potentiels évoqués cognitifs ont découvert des anomalies cérébrales en l’absence de symptômes cliniques observables chez l'adulte. Toutefois, peu de données scientifiques sont disponibles sur les répercussions d’un tel impact sur le cerveau en développement. Le but de l’étude était de déterminer s’il existe une relation entre l’âge de survenue au moment de la commotion et la gravité des déficits. Cette étude transversale a évalué le fonctionnement cognitif de sportifs par des tests neuropsychologiques ainsi que les mécanismes neuronaux de l’orientation de l’attention (P3a) et de mise à jour de l’information en mémoire de travail (P3b) à l’aide de potentiels évoqués cognitifs. Les athlètes étaient répartis selon trois groupes d’âge [9-12 ans (n=32); 13-16 ans (n=34); adultes (n=30)], la moitié ayant subi une commotion dans la dernière année. Les comparaisons entre les groupes ont été effectuées par une série d’ANOVAs. Comparativement au groupe contrôle, les adolescents commotionnés présentaient des déficits de mémoire de travail. Les athlètes commotionnés démontraient une réduction de l’amplitude de la P3b comparativement aux non-commotionnés. Les résultats illustrent la présence de déficits neurophysiologiques persistants et ce, au moins six mois suivant l’impact. Les enfants semblent aussi sensibles que les adultes aux effets délétères d’une commotion cérébrale et les conséquences s’avèrent plus sévères chez l’adolescent. / Sport-related concussions are common injuries among professional athletes as well in adolescents and children participating in organized sports. Although the majority of concussions resolve rapidly in adults (7-10 days), recovery could be different in younger athletes. Several studies using event-related potentials show that adult athletes have cerebral anomalies in the absence of clinical symptoms. However, the consequences of a sport-related concussion on the developing brain are less known. The purpose of this study was to determine whether age differences exist with respect to cognitive functioning following a sport-related concussion. This cross-sectionnal study assessed cognitive functioning using standardized neuropsychological tests as well the neuronal mechanisms associated with the re-orienting attention (P3a) and with the update of information in working memory (P3b), using event-related potentials. Athletes were divided into three age groups [9-12 yrs (n=32); 13-16 yrs (n=34); and adults (n=30)] half of whom suffered from a sport-related concussion. Group comparisons were investigated with a series of ANOVAs. Specifically, concussed adolescents showed persistent deficits in working memory compare with their non injured counterparts. Concussed athletes from all age groups had significantly lower amplitude for the P3b component of their ERPs compared to their non injured teammates. No age-related differences for ERP’s were found among the concussed groups. These data suggest persistent neurophysiological deficits that are present at least 6 months following a concussion. Children appear to be as sensitive as adults to the consequences of a concussion and adolescents seem experience the most severe outcomes.

Exposure to interparental conflict has been implicated in children's development. Research suggests that underlying mechanisms, such as neuropsychological indicators of cognitive processes, may shed light on how exposure to interparental conflict differentially influences children's outcomes over time. Event-related potentials (ERP), extracted from electroencephalogram data, allow for examination of neuropsychological markers of cognition based on precise timing and scalp topography of electrical activity in the brain. For example, the late positive potential (LPP) ERP component has been implicated in the timing and magnitude of sustained attention and emotion regulation processes elicited in response to emotionally salient stimuli. LPP amplitudes and peak latencies were compared for a community sample of 23 children (9-11 years of age, 12 females) during an oddball task, which used images of couples looking angry, happy, and neutral toward each other. Linear mixed models were used to analyze whether children's perceptions of interparental conflict, and whether they were from high- compared to low-conflict homes, influenced their level of neuropsychological resources directed toward angry compared to happy emotionally-charged interpersonal images. Significant results were found for when children were directed to respond to angry images. Differences emerged in LPP amplitudes for all children in the sample, with the greatest amplitudes produced for happy images compared to neutral and angry images. Regarding conflict exposure and perceptions of conflict, children from homes with greater levels of conflict and children who blamed themselves for conflicts they witnessed between parents produced greater LPP amplitudes when happy trials were presented compared to neutral trials. Finally, females reached their maximum LPP amplitude faster than males for neutral trials compared to angry trials. Results are discussed in terms of the implications for children's processing of interpersonal emotions as it is related to underlying neuropsychological mechanisms for sustained attention and emotion regulation.

D’importantes faiblesses dans l'expérience, l'expression et la reconnaissance des émotions chez les patients souffrant de schizophrénie ont été relativement bien documentées au fil des années. Par ailleurs, les différences sexuelles dans le comportement et l'activité cérébrale associée aux processus émotionnels ont été rapportées dans la population générale. Il apparaît donc surprenant que si peu ait été publié afin d’améliorer notre compréhension des différences sexuelles dans la schizophrénie. La présente étude vise à comparer les différences dans le mode de fonctionnement d’hommes et de femmes atteints de schizophrénie. Il s’agit, avec cette population, de comprendre la réponse comportementale et électrocorticale associés au traitement des images émotionnelles. Ces données ont été enregistrées à l’aide des potentiels évoqués cognitifs (PÉC), et des temps de réponses lors du visionnement passif d’images émotionnelles. L’activation des composantes P200, N200 antérieure et P300 a été comparée chez 18 patients avec une schizophrénie stabilisée (9 femmes et 9 hommes) et 24 participants formant un groupe contrôle (13 femmes et 11 hommes) sans problème psychiatrique. L’analyse des PÉC a globalement révélé que la valence et l’activation émotionnelle influencent les composantes précoces de même que les composantes tardives de façon indépendante, ce qui prouve l’importance d’investiguer ces deux dimensions émotionnelles sur plusieurs composantes. Une découverte d’intérêt réside dans l’observation de différences sexuelles qui entrent en interaction avec le groupe, à différentes latences et attribuées tant à la valence qu’à l’activation. De plus, les données provenant des hormones gonadiques montrent que la progestérone pourrait avoir un impact fonctionnel sur les processus de traitement des émotions tant chez les femmes que chez les hommes. Cependant, d’autres études sont nécessaires pour pouvoir comprendre davantage le rôle des hormones gonadiques en neuropsychopathologie. / Prominent disturbances in the experience, expression and emotion recognition in patients with schizophrenia have been relatively well documented over the last few years. Furthermore, sex differences in behavior and brain activity associated with emotional processes have been reported in the general population. It is therefore surprising that so little has been done to further our understanding of potential differences between sexes in schizophrenia. In the present study we compared the behavioral and electrophysiological responses related to emotional processes of individuals with schizophrenia and individuals from the general population, while taking into consideration the valence and arousal of presented stimuli, as well as sex of tested participants. These data were measured with the help of event-related potentials (ERP) during passive viewing of emotional pictures. Activation of components P200, N200 and P300 were compared in 18 schizophrenia patients (9 women and 9 men) and 24 controls (13 women and 11 men). The ERP analysis revealed that valence and arousal influences early and late components independently, which demonstrates the importance of investigating these two emotional dimensions. Moreover, several significant differences between groups (i.e. clinical vs. control and men vs. women), attributed to the valence and arousal, were found in the ERP data in the stream of emotional processing. Also, data from gonadal hormones show that progesterone may have a functional impact on emotional processes among women and men. However, further studies are needed to better understand the role of gonadal hormones in neuropsychopathology.

Abstract The aim of this study was to discover attention- and inhibitory control-related differences in the electrical activity of the brain in 6- to 9-year-old children who stutter (CWS) compared to typically developed children (TDC). For studies I and II, the study group consisted of 11 CWS (mean age 8.1 years, age range 6.3–9.5 years; all boys) and 19 fluently speaking children (mean age 8.1 years, age range 5.8–9.6 years; 7 girls). In study III, the participants were twelve boys who stutter (mean age 7.97 years, range 6.3–9.5 years) and 12 typically developed, fluently speaking boys (mean age 8.01 years, range 5.8–9.6 years). The CWS were recruited through local speech therapists and special teachers and newspaper advertisements, while controls were recruited from schools and preschools and among families of department staff and friends. Electroencephalography (EEG) was recorded during a visual Go/Nogo task, which forms a conflict between the pre-potent Go-response and inhibition of response in the Nogo condition, demanding inhibitory control. This EEG data was investigated with conventional event-related potentials (ERP) analysis, potential map and global field power (GFP) analysis and a time-frequency analysis including the periods between tasks. In the ERP analysis, the CWS had a delayed N2 component in the Go condition and a poorly defined P3 component. The potential maps and GFP waveforms confirmed the findings in the Go condition, but also revealed differences in the Nogo condition, described as a prolonged and excessive N2component and an absent P3 component in the CWS. These results indicate problems in the evaluation and classification of the stimulus and the response preparation and inhibition of the response. In the time-frequency analysis, the CWS showed reduced occipital alpha power in the “resting” or preparatory period between visual stimuli, particularly in the Nogo condition. Therefore, the CWS demonstrate reduced inhibition of the visual cortex in the absence of visual stimuli, which is likely related to problems in attentional gating. This newly discovered lack of occipital alpha modulation indicates elementary differences in the regulation of visual information processing in CWS. These findings support the view of stuttering as part of an extensive brain dysfunction involving also attentional and inhibitory networks. / Tiivistelmä Tutkimuksen tavoitteena oli tunnistaa tarkkaavuuteen ja inhibitiokontrolliin liittyviä eroja aivojen sähköisessä toiminnassa 6–9-vuotiailla lapsilla, jotka änkyttävät verrattuna tavanomaisesti kehittyviin lapsiin. Osatöissä I ja II koeryhmässä oli 11 änkyttävää lasta (iän keskiarvo 8.1 vuotta, ikäjakauma 6.3–9.5 vuotta) ja verrokkiryhmässä 19 sujuvasti puhuvaa lasta (keskiarvo 8.1 vuotta, jakauma 5.8–9.6 vuotta; 7 tyttöä). Osatyössä III koeryhmässä oli 12 änkyttävää poikaa (keskiarvo 7.97, jakauma 6.3–9.5 vuotta) ja verrokkiryhmässä 12 sujuvasti puhuvaa poikaa (keskiarvo 8.01 vuotta, jakauma 5.8–9.6 vuotta). Koehenkilöitä haettiin puheterapeuttien ja erityisopettajien välityksellä sekä lehti-ilmoituksilla. Verrokkiryhmän osallistujat rekrytoitiin kouluista, esikouluista sekä henkilökunnan ja ystävien perheiden joukosta. Elektroenkefalografia (EEG) rekisteröitiin visuaalisen Go/Nogo-tehtävän aikana. Tehtävässä ennakoidun Go-vasteen ja Nogo-tilanteessa vaadittavan reaktiosta pidättäytymisen välille syntyvä ristiriita kuormittaa inhibitiokontrollia. EEG-dataa arvioitiin herätevasteiden avulla, tutkimalla jännitekarttojen ja koko pään jännitevaihteluiden eroja sekä käyttämällä aika-taajuusanalyysia, mihin sisältyi myös tehtävien välinen aika. Herätevasteanalyysissä änkyttävillä lapsilla oli viivästynyt N2-vaste Go-tilanteessa ja huonosti erottuva P3-vaste. Jännitekarttojen ja koko pään jännitevaihteluiden perusteella tämä löydös vahvistui, mutta ryhmät erosivat toisistaan myös Nogo-tilanteessa. Änkyttävillä lapsilla N2-vaste oli pidentynyt ja voimakkaampi ja P3-vaste puuttui. Löydökset viittaavat ongelmiin ärsykkeen arvioinnissa ja luokittelussa sekä reaktion valmistelussa ja inhibitiossa. Aika-taajuusanalyysissa änkyttävillä lapsilla oli okkipitaalialueilla merkittävästi vähemmän alfataajuista toimintaa tehtävien välisen ”lepotilan” tai valmistautumisvaiheen aikana erityisesti Nogo-tilanteessa. Änkyttävillä lapsilla näköaivokuoren inhibitio ärsykkeen puuttuessa on näin ollen heikentynyt, mikä viittaa häiriöön tarkkaavuuden suuntaamisessa. Tämä todettu alfatoiminnan säätelyn puuttuminen ilmentää perustavanlaatuisia eroja näköärsykkeen käsittelyssä änkyttävillä lapsilla. Löydökset tukevat näkemystä änkytyksestä osana laaja-alaista aivojen toiminnan häiriötä, joka käsittää todennäköisesti myös tarkkaavuuteen ja inhibitiokontrolliin liittyviä verkostoja.

The present study aims to explore the relationship between proficiency level and semantic retrieval in the second language. A group of Korean bilinguals who speak English with high proficiency performed semantic relatedness judgement tasks of two hundred English word pairs. Unbeknownst to the participants, half of the words in both the related and the unrelated categories contained a "hidden prime"—a common first syllable shared by the two words, if translated into Korean. Each participant's event-related potential (ERP) was recorded while reading the words. While a former study by Thierry and Wu (2007) found that Chinese-English bilinguals were affected by the hidden primes, thus causing a "N400 reduction effect" in their averaged ERP, the bilingual group of the present study was unaffected by the hidden primes. The difference between the bilingual groups' performance between Thierry and Wu's study and the present study is likely caused by the higher English proficiency of the bilingual group in the present study. This provides additional evidence supporting the Revised Hierarchical Model of semantic retrieval proposed by Kroll and Steward (1994), which suggests that increased proficiency leads to reduced reliance on the first language during second language semantic retrieval.

This study examined the effect of an 8-week, progressive exercise intervention on neural responses, specifically N2 amplitude as a measure of inhibitory control, to pictures of food. Healthy women ages 18-44 years were randomized to a morning (AM) exercise group or evening (PM) exercise group. The AM group did moderate-to-vigorous intensity exercise on 4 days per week between 6:30 and 9:30 a.m. while the PM group had the identical volume of exercise between 6:30 and 9:30 p.m. Neural responses, eating behaviors, cardiovascular fitness outcomes, and body weight/composition were measured at baseline and after the 8-week intervention. The N2 amplitude in response to pictures of high- and low-calorie foods was assessed using electroencephalography during a go/no-go task. Dietary restraint, emotional eating, and external eating were assessed using the Dutch Eating Behavior Questionnaire. VO2peak, HRmax, and time to completion were measured during a maximal treadmill test. Body weight was measured on a digital scale, and body composition was measured using dual-energy x-ray absorptiometry. There was not a significant task (go, no-go) × group (AM, PM) × period (baseline, 8 weeks) interaction (F = 0.18; p = 0.677), but there was a main effect of exercise over 8 weeks (F = 6.26; p = 0.017) with increased N2 amplitude following the intervention. There was not a significant interaction as a function of picture type (high-calorie, low-calorie), task, group, and period (F = 0.52; p = 0.478). Changes in body weight and neural outcomes were not significantly associated with changes in eating behaviors for either group (ps < 0.05). There was a significant group × period interaction for body weight (F = 4.90; p = 0.032). Body weight increased by 0.79 ± 1.16 kg in the AM group and decreased by 0.21 ± 1.46 kg in the PM group (effect size = 0.77; CI = 0.15-1.35). There was not a significant group × period interaction for body fat percentage, total body fat or fat-free mass (ps < 0.05). When examining the main effect of exercise on cardiovascular fitness outcomes, VO2peak was not different (F = 1.80; p = 0.187), time-to-completion on treadmill increased (F = 6.51; p = 0.014), and HRmax during the treadmill test was significantly lower (F = 5.49; p = 0.025). This study suggests that 8 weeks of exercise training may increase the inhibitory response to pictures of both high- and low-calorie foods. However, time of day of exercise did not influence this response. Eight weeks of exercise training did not change self-reported dietary restraint, external eating, or emotional eating, and there was no correlation between these eating behaviors and inhibitory control. However, evening exercise was more beneficial for body weight than morning exercise. Given the novelty of this study and its results, additional studies on the influence of time of day of exercise on weight management are needed.

My objectives are twofold: 1/ investigating the cognitive and electrophysiological mechanisms of response inhibition in healthy or ADHD adults, 2/ providing a training program to reduce impulsivity. According to Braver (2012), action regulation permits to control impulsivity in two ways: proactive inhibition, effected before motive commands and reflected in an event related potential (ERP) in the N2 wave, and reactive inhibition, a rapid correction mechanism interrupting a motor process already well underway, reflected by the P3 wave. / My objectives are twofold: 1/ investigating the cognitive and electrophysiological mechanisms of response inhibition in healthy or ADHD adults, 2/ providing a training program to reduce impulsivity. According to Braver (2012), action regulation permits to control impulsivity in two ways: proactive inhibition, effected before motive commands and reflected in an event related potential (ERP) in the N2 wave, and reactive inhibition, a rapid correction mechanism interrupting a motor process already well underway, reflected by the P3 wave.