The term cognitive control refers to a variety of mental processes that support goal-directed behavior. In the current dissertation, I focus on the role of cognitive control in situations where a weaker (but task-relevant) source of information must be selected over a stronger (but task-irrelevant) source of information. The efficiency with which individuals select information in the face of distraction has classically been viewed as a function of static control settings tied to task instructions. Recent evidence suggests, however, that variations in the efficiency of cognitive control can be induced by variations in stimulus experience and that multiple control settings may be maintained for a single task. To date, little is known about the mechanisms that support this more flexible form of control. Across six experiments, I find evidence for the formation of multiple control settings that are relatively long lasting but fragile. Multiple control settings can be maintained within a single experiment and can last over relatively long periods of time, however, without the proper contextual support these control settings fall apart. These results emphasize the important role of stimulus experience in studies of cognitive control.

Cognitive control-e.g. the abilities to pay attention, to ignore irrelevant input, and to switch between tasks- has received much attention in recent literature. Since both of their languages are activated in parallel, bilinguals have been suggested to have improved cognitive control skills in both the linguistic and non-linguistic domain (e.g., Bialystok, 2017), but inconsistent results (e.g., Hilchey, Saint-Aubin, & Klein, 2015) have lead to a heated debate in the field. However, when found, the effects of bilingualism on cognitive control appear to be generally positive (Valian, 2015). Furthermore, earlier bilingualism has been linked to greater cognitive benefits (Yow & Li, 2015), and Green and Abutalebi's (2013) Adaptive Control Hypothesis (ACH) suggests that the bilingual environment also plays a role. The aim of the current study is to investigate the role of the Age of Acquisition (AoA) of the second language on cognitive control in young adult bilinguals in two different linguistic environments, as well as to examine the underlying processes of cognitive control via event-related brain potentials (ERPs). Two research questions are focused on: 1) Which, if any, cognitive control abilities are enhanced by bilingualism? and 2) Does the type of bilingual experience modulate observed effects? The present study uses the non-linguistic Attention Network Test (ANT; Fan et al., 2002), in which sets of arrows appear with a central target arrow in either a congruent (e.g. ← ← ← ) or incongruent (e.g. ← → ← ) condition, to examine Alerting, Orienting, and Executive Control networks, and a linguistic Stroop task (Stroop, 1935), in which colour terms appear in congruent (i.e. the word "red" presented in red font) and incongruent (i.e. the word "red" presented in green font) conditions, to examine language processing of English-French bilinguals in Canada and in Japanese-English bilinguals in Japan. In addition, Canadian participants also completed an ERP version of the Stroop task to examine possible underlying differences. The results of this series of experiments revealed a complex, yet interesting picture of bilingual cognitive control: although bilingual advantages were not consistent, there was support for earlier bilingualism being more beneficial to cognitive control. Particularly, results show Executive Control advantages for Simultaneous bilinguals, and significant differences between Simultaneous and Early Sequential bilinguals (typically grouped together as "early") in the Stroop task, demonstrating that balanced, proficient bilingualism enhances both linguistic and non-linguistic control. Interestingly, these effects only become apparent when both languages are mixed in the task, in line with suggestions that young adults’ cognitive resources need to be maximally taxed before advantages become apparent. Indeed, ERP results confirmed a greater engagement of cognitive resources in the more difficult version of the task. Although AoA and environment turned out to be confounded, there were still differences between Canadian and Japanese participants. Most notably, Canadian participants appeared to have better Executive Control. Taken together, the current work concludes that despite increased processing load, bilingual cognition does not suffer. Instead, cognition may receive a boost from dual language experience in some cases. Several rarely-explored factors were examined, and the complex results suggest possible areas that would benefit from further exploration, as well as raise interesting questions for future research.

The main idea of this thesis is to define and formulate the role of cognitive control in cognitive dynamic systems and complex networks in order to control the directed flow of information. A cognitive dynamic system is based on Fuster's principles of cognition, the most basic of which is the so-called global perception-action cycle, that the other three build on. Cognitive control, by definition, completes the executive part of this important cycle. In this thesis, we first provide the rationales for defining cognitive control in a way that it suits engineering requirements. To this end, the novel idea of entropic state and thereby the two-state model is first described. Next, on the sole basis of entropic state and the concept of directed information flow, we formulate the learning algorithm as the first process of cognitive control. Most importantly, we show that the derived algorithm is indeed a special case of the celebrated Bellman's dynamic programming. Another significant key point is that cognitive control intrinsically differs from the generic dynamic programming and its approximations (commonly known as reinforcement learning) in that it is stateless by definition. As a result, the main two desired characteristics of the derived algorithm are described as follows: a) it is convergent to optimal policy, and b) it is free of curse of dimensionality. Next, the predictive planning is described as the second process of cognitive control. The planning process is on the basis of shunt cycles (called mutually composite cycles herein) to bypass the environment and facilitate the prediction of future global perception-action cycles. Our results demonstrate predictive planning to have a very significant improvement to the functionality of cognitive control. We also deploy the explore/exploit strategy in order to apply a simplistic form of executive attention. The thesis is then expanded by applying cognitive control into two different applications of practical importance. The first one involves cognitive tracking radar, which is based on a benchmark example and provides the means for testing the theory. In order to have a frame of reference, the results are compared to other cognitive controllers, which use traditional Q-learning and the method of dynamic optimization. In both cases, the new algorithm demonstrates considerable improvement with less computational load. For the second application, the problem of observability in stochastic complex networks has been picked due to its importance in many practical situations. Having known cognitive control theory and its significant performance, the idea here is to view the network as the environment of a cognitive dynamic system; thereby, cognitive dynamic system with the cognitive controller plays a supervisory role over the network. The proposed methodology differs from the state-of-the-art in the literature in two accounts: 1) stochasticity both in modelling as well as monitoring processes, and 2) complexity in terms of edge density. We present several examples to demonstrate the information processing power of cognitive control in this context too. The thesis will finish by drawing line for future research in three main directions. / Thesis / Doctor of Philosophy (PhD)

Exerting cognitive self-control leads to subsequent decrements in muscular and cardiovascular endurance performance. According to the Process Model of self-control, affective feeling states may account for later self-control impairments. Affective feeling states are sensitive to exercise and show a pronounced negative shift in valence at the ventilatory threshold (VT). The purpose of this study was to investigate feeling states in response to a challenging cognitive control task (stop-signal task; SST) followed by a graded exercise task to exhaustion (GXT). Recreationally active participants (N = 20; Mage = 20.25) completed two testing sessions separated by one week. Sessions were counterbalanced, with either a control (SST-C) or experimental (SST-E) task performed prior to each GXT. Feeling states were measured using the Feeling Scale (FS) and Felt Arousal Scale (FAS) throughout both tasks. Time to exhaustion on the GXT was significantly shorter following the SST-E than the SST-C (p < .05; d = .49). Repeated measures MANOVA showed similar within-task changes in FS in both conditions, but no significant differences between conditions during the SST tasks; however, FAS scores were significantly higher during the SST-E compared to the SST-C (p < .01). There were no significant differences in feeling states prior to, or upon completion of, the GXTs. However, FS was significantly less positive at iso-time corresponding to predicted VT in the SST-E condition (p < .05). Results show feeling states during exercise are altered by prior cognitive control exertion. Decreases in positive valence in concert with increased activation may prime a negative shift in affect as exercise becomes more strenuous and thereby reduce self-control (exercise tolerance), as predicted by the Process Model. Alternatively, shifts in affect may reflect responses to physiological manifestations of fatigue that carry over from cognitive to physical tasks and become salient at moderate exercise intensities. / Thesis / Master of Science (MSc)

As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory, cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. Abstract As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. Abstract As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. / Thesis / Doctor of Philosophy (PhD) / Cognitive control refers to our ability to direct our actions in accordance with our goals. Traditionally, the construct of cognitive control was assumed to be synonymous with the construct of free will. In recent years, cognitive psychologists have questioned the volitional nature of cognitive control. Generally speaking, this thesis investigates the following question; to what extent is control over the allocation of our attentional resources governed by our conscious intentions, or, to what extent are such processes recruited automatically? The results suggest that controlled and automatic processes are not dichotomous in nature, but rather, contribute to performance interactively. While conscious intentions may play a role in the establishment of control procedures in novel contexts, once established these control procedures can be brought online automatically. Decisions regarding the need for effortful processing, given the current context, likely shape the construction of these automatized routines.

It is well established that childhood adversity is associated with long lasting effects on development including both negative physical and mental health outcomes. Research demonstrates that adverse childhood experiences influence neurodevelopment and propose that this may be a mechanism linking adversity and psychopathology. However, little is known how the timing and type of maltreatment experiences may differentially impact longitudinal changes in neural processes of risk-related decision making. Using conditional growth curve modeling, we examined how abuse and neglect across three developmental periods (early childhood, school age, and adolescence) are associated with longitudinal changes in task-based functional connectivity during risk-processing and cognitive control. The current sample included 167 adolescents (13-14 years old at Time 1; 53% male), assessed annually for six years. At each of the six time points, adolescents completed a lottery choice task and a cognitive control task while blood-oxygen-level-dependent (BOLD) responses were monitored with functional magnetic resonance imaging (fMRI). Adolescents reported on maltreatment experiences occurring during ages 1 to 18. Generalized psychophysiological interactions (gPPI) was used to examine task- based functional connectivity in the insula and dACC (dorsal anterior cingulate cortex) during both risk processing and cognitive control, respectively. Although no sensitive periods emerged for the effects of abuse or neglect on functional connectivity during risk processing, chronic abuse (abuse occurring in more than one developmental period) significantly predicted weaker insula-dACC connectivity in late adolescence. For functional connectivity during cognitive control, adolescence emerged as a potential sensitive period for neglect, such that those with neglect experiences occurring during ages 13 to 18 showed slower improvements in dACC- insula connectivity across adolescence. Chronic neglect was also associated with slower improvements in dACC-insula connectivity. Additionally, chronic abuse was significantly associated with stronger improvements in dACC-insula connectivity across adolescence. Collectively, these results suggest that abuse may be linked to a delayed maturation in neural connectivity associated with valuation, but an accelerated maturation in neural connectivity associated with cognitive control. Furthermore, neglect may be linked to a delayed maturation in neural connectivity associated with cognitive control. Both sets of findings involved functional connectivity in both the dACC and insula, important regions involved in salience processing. These findings elucidate the distinct effects of abuse and neglect on connectivity in regions involved in risk-related decision making, including valuation and cognitive control. Future work will benefit from examining how these different pathways may lead to outcomes such as health risk behaviors and psychopathology. / M.S. / Childhood adversity is associated with long lasting effects on development including both negative physical and mental health outcomes. Research shows that adverse childhood experiences influence brain development. However, little is known how the timing and type of maltreatment experiences may differentially impact changes in brain processes of risky decision making across adolescence. We examined how abuse and neglect across three developmental periods (early childhood, school age, and adolescence) are associated with changes in functional connectivity during risk-processing and cognitive control. The current sample included 167 adolescents (13-14 years old at Time 1; 53% male), assessed annually for six years. At each of the six time points, adolescents completed a lottery choice task and a cognitive control task while blood-oxygen-level-dependent (BOLD) responses were monitored with functional magnetic resonance imaging (fMRI). Adolescents reported on maltreatment experiences occurring during ages 1 to 18. Generalized psychophysiological interactions (gPPI) was used to examine task- based functional connectivity in the insula and dACC (dorsal anterior cingulate cortex) during both risk processing and cognitive control, respectively. Results showed that chronic abuse (abuse occurring in more than one developmental period) significantly predicted weaker insula- dACC connectivity in late adolescence. For functional connectivity during cognitive control, those with neglect experiences occurring during ages 13 to 18 showed slower improvements in dACC-insula connectivity across adolescence. Chronic neglect was also associated with slower improvements in dACC-insula connectivity. Additionally, chronic abuse was significantly associated with stronger improvements in dACC-insula connectivity across adolescence. Both sets of findings involved functional connectivity in both the dACC and insula, important regions involved in salience processing. These findings elucidate the distinct effects of abuse and neglect on connectivity in regions involved in risk-related decision making, including valuation and cognitive control. Future work will benefit from examining how these different pathways may lead to outcomes such as health risk behaviors and psychopathology.

Indiana University-Purdue University Indianapolis (IUPUI) / Problematic alcohol consumption develops concurrently with deficits in decision-making. These deficits may be due to alterations in dorsal medial prefrontal cortex (dmPFC) neural activity, as it is essential for the evaluation and implementation of behavioral strategies. In this study, we hypothesized that differences in cognitive control would be evident between Wistars and alcohol-preferring P rats. Cognitive control can be split into proactive and reactive components. Proactive control maintains goal-directed behavior independent of a stimulus whereas reactive control elicits goal-directed behavior at the time of a stimulus. Specifically, it was hypothesized that Wistars would show proactive control over alcohol-seeking whereas P rats would show reactive control over alcohol-seeking. Proactive control in our rodent model is defined as responding to distal task cues whereas reactive control is responding to proximal cues. This was tested in rodents performing a 2-way Cued Access Protocol (2CAP) that facilitates measurements of alcohol seeking and drinking. Congruent sessions were the typical, default 2CAP sessions that consisted of the CS+ being on the same side as alcohol access. These were compared with incongruent sessions where alcohol access was opposite of the CS+. Wistars exhibited an increase in incorrect approaches during the incongruent sessions, which was not detectable in P rats. A trial-by-trial analysis indicated that the increases in incorrect responses was explained by Wistars utilizing the previously learned task-rule, whereas the P rats did not. This motivated the subsequent hypothesis that neural activity patterns corresponding to proactive control would be observable in Wistars but not P rats. Principal Component Analysis indicated that neural ensembles in the dmPFC of Wistars exhibited decreased activity to the cue light in incongruent sessions whereas P rat ensembles displayed increased activity at timepoints associated with the onset and end of alcohol access. Overall, it was observed that P rats showed the most differences in neural activity at times relevant for alcohol delivery; specifically, when the sipper came into the apparatus and left. Conversely, Wistars showed differences prior to approach as evidenced by both differences in cue-related activity as well as differences in spatial-strategies. Together, these results support our hypothesis that Wistars are more likely to engage proactive cognitive control strategies whereas P rats are more likely to engage reactive cognitive control strategies. Although P rats were bred to prefer alcohol, differences in cognitive control phenotypes may have concomitantly occurred that are of clinical relevance.

No description available.

Exerting cognitive control can lead to mental fatigue and impair self-regulation of subsequent physical performance. However, current understanding is limited due to a number of factors. First, studies have employed manipulations involving either high or low cognitive demands, failing to test whether a dose-response relationship exists between mental fatigue and physical performance. Second, the role of several psychological variables among the mental fatigue – physical performance relationship remains unclear. Third, current literature lacks generalizability in that existing findings have largely been derived from studies involving active samples performing physical tasks that the general population may not commonly engage in for health and fitness benefits. Lastly, there has been little research examining intervention strategies that may attenuate the effects of mental fatigue on physical activity behaviour. This dissertation aimed to advance our understanding of self-regulation of physical activity behaviour in response to mental fatigue by addressing shortcomings within the literature discussed above. Study 1 examined whether a dose-response relationship exists for mental fatigue and physical performance. Results showed a performance threshold exists between 4 and 6 minutes of exposure to a mentally fatiguing cognitive control task. Beyond this threshold, task self-efficacy also showed uniform reductions which mediated the mental fatigue – physical performance change relationship. Findings are consistent with previous research and reveal self-efficacy is a key variable that accounts for the negative effects of mental fatigue on physical performance. Study 2 investigated the hypothesis that offering a performance contingent monetary incentive would attenuate the negative carryover effects of mental fatigue on physical performance. Findings showed mental fatigue caused characteristic declines in physical performance; however, incentives countered the effects of mental fatigue and led to performances equal to those witnessed in a non-fatigued state. Interestingly, incentives did not provide any additional benefit for performance when not fatigued. Findings support motivational accounts of self-regulation, although incentives may lack practicality and may not be a cost-effective means to alter exercise behaviour. Study 3 examined the effect of mental fatigue on intended physical exertion and exercise performance reflective of current public health guidelines for physical activity in a sample comprised of insufficiently active university students. Findings showed mental fatigue alters the amount of physical effort people are willing to invest in an exercise workout and follow through with those intentions by doing less work and exercising at a lower heart rate intensity. These are the first results showing people may deliberately adjust their physical effort to cope with mental fatigue. Study 4 investigated whether heart rate biofeedback moderates the effects of mental fatigue on vigorous-intensity exercise reflective of current public health physical activity guidelines and the effects of mental fatigue on pre-exercise motivational cognitions. Results showed mental fatigue was associated with decreases in intended physical effort and commitment to vigorous-intensity exercise goals which corresponded with reductions in exercise intensity (i.e., HRAVE) and total work performed when people exercised without feedback. However, HR biofeedback attenuated the negative carryover effects of mental fatigue on exercise behaviour, restoring exercise intensity and performance to levels witnessed in a non-fatigued state. Similar to incentives, biofeedback offered no further benefits for performance when not fatigued. Findings align with predictions of Control Theory and suggest biofeedback using widely available physical activity monitors in combination with goals can improve intensity-based physical activity guideline adherence when confronted with barriers such as mental fatigue. / Thesis / Doctor of Philosophy (PhD) / Effortful cognitive control exertion can lead to mental fatigue and impair self-regulation of subsequent physical performance. However, current understanding is limited due to a number of factors. This thesis addressed several gaps in the literature through a systematic examination of potential mediators and moderators of the mental fatigue - physical performance relationship. Findings revealed downstream physical performance impairments are dependent on exceeding a critical mental fatigue threshold. Reductions in pre-exercise cognitions including self-efficacy, intended physical exertion and goal commitment all correspond with negative changes in exercise performance. Evidence also highlights the generalizability of fatigue-induced effects by demonstrating that insufficiently active people engaging in exercise for health and fitness benefits down-regulate exercise performance in the face of mental fatigue. Incentives and heart rate biofeedback can attenuate the effects of mental fatigue on physical performance. Collectively, evidence provides insight for theories of self-control and can be interpreted within Muller and Apps (2018) neurocognitive framework of motivational fatigue.

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