Daydreaming Styles and Brain Functional Connectivity

"Intrinsic modes of thinking, like daydreaming, are in large part related to more general thinking styles. Through neuroimaging techniques, we are able to identify daydreaming connectivity within brain networks. The brain’s default mode network is typically associated with unintentional thinking, while the fronto-parietal network involves more intentional forms of cognition. In this study, resting brain states were collected, and participants completed the Short Imaginal Process Inventory (SIPI) to ascertain distinctive daydreaming patterns among the individuals, including positive constructive (PC), guilt and fear of failure (GF), and poor attentional control (PA) styles. Connectome-based predictive modeling was used to estimate the pattern of each participant’s daydream connectivity from whole-brain, resting-state functional connectivity. In PC individuals, node connections found within frontal-parietal and default mode networks, which supports previous evidence of default mode activity associated with goal-directed cognition. Limbic network connectivity in GF individuals suggests more emotional qualities within their daydreams. Dorsolateral prefrontal cortex and subcortical/cerebellum activity in PA individuals suggests low maintenance of attention, as previously found in ADHD individuals. By delving into the individual differences of daydreaming styles, our research has contributed to a more comprehensive understanding of overall brain functional connectivity as it pertains to the intentionality and characteristic quality of different daydreamers.

Automatic recognition of personality profiles using EEG functional connectivity during emotional processing

Personality is the characteristic set of an individual’s behavioral and emotional patterns that evolve from biological and environmental factors. The recognition of personality profiles is crucial in making human−computer interaction (HCI) applications realistic, more focused, and user friendly. The ability to recognize personality using neuroscientific data underpins the neurobiological basis of personality. This paper aims to automatically recognize personality, combining scalp electroencephalogram (EEG) and machine learning techniques. As the resting state EEG has not so far been proven efficient for predicting personality, we used EEG recordings elicited during emotion processing. This study was based on data from the AMIGOS dataset reflecting the response of 37 healthy participants. Brain networks and graph theoretical parameters were extracted from cleaned EEG signals, while each trait score was dichotomized into low- and high-level using the k-means algorithm. A feature selection algorithm was used afterwards to reduce the feature-set size to the best 10 features to describe each trait separately. Support vector machines (SVM) were finally employed to classify each instance. Our method achieved a classification accuracy of 83.8% for extraversion, 86.5% for agreeableness, 83.8% for conscientiousness, 83.8% for neuroticism, and 73% for openness

Neurobiological Impact of HIV Infection and Chronic Cannabis Use

Neuroimaging research has identified brain alterations linked with the human immunodeficiency virus (HIV) that contribute to cognitive declines characterizing the disease. Given cannabis’s (CB’s) anti-inflammatory properties, use prevalence among people living with HIV (PLWH), and impact on neurocognition, my dissertation utilizes a between-groups study design to interrogate separate and interactive effects of HIV and CB on fMRI measures of brain activity. We investigate (1) task-based brain activity at the regional-level, (2) insular resting-state functional connectivity (rsFC) at the circuit-level, and (3) large-scale brain network interactions at the systems-level. Participants (N=114) were stratified into four groups (HIV+/CB+; HIV+/CB-; HIV-/CB+; HIV-/CB-) and underwent fMRI scanning while completing an Error Awareness Task (EAT) and while at rest. Participants also completed a battery of instruments including subjective reports of cognitive failures, and objective measures of cognition and medication management abilities. Blood samples quantified disease severity (viral load) and inflammation (tumor necrosis factor alpha [TNF-α]). Regarding task-based brain activity, PLWH displayed a lack of error-related deactivation in two default mode network (DMN) regions (posterior cingulate cortex [PCC], medial prefrontal cortex [mPFC]). Across all participants, reduced error-related PCC deactivation correlated with reduced medication management abilities and mediated the effect of HIV on such abilities. Regarding insular circuitry, we observed interactive HIVxCB effects on rsFC between two anterior insula (aI) subregions and sensorimotor cortices such that, CB use normalized altered rsFC that was observed among non-using PLWH and correlated with decreased somatic complaints and increased inflammation. Finally, regarding large-scale network interactions, PLWH displayed increased salience network (SN)-DMN rsFC that was associated with diminished error-awareness. These results demonstrate that insufficient error-related DMN suppression and heightened SN-DMN rsFC are linked with HIV and have consequences for error-processing and medication management. Additionally, these outcomes suggest a potential normalizing effect of CB on altered insula-sensorimotor neurocircuitries among PLWH and begin to elucidate inflammatory mechanisms through which CB use may impact brain function in the context of HIV

Frontal-limbic brain processes in healthy individuals : environmental, epigenetic and behavioral correlates

Des altérations au niveau du cerveau ont été observées dans le circuit fronto-limbique (incluant le cortex préfrontal, le cortex cingulaire antérieur, hippocampe et amygdale), densément innervé avec la sérotonine, chez les individus souffrant de troubles affectifs. La relation entre les processus fronto-limbiques et le bien-être émotionnel peut être influencée par la génétique et l’environnement, ainsi que par leur interaction (GxE). Toutefois, les mécanismes spécifiques sous-tendant cette relation ne sont pas connus à ce jour. Un mécanisme physiologique sous-jacent l’effet GxE sur l’expression des gènes est la méthylation de l’ADN. Le but de cette thèse était, donc, d'étudier les effets environnementaux sur et la pertinence de la méthylation de l'ADN pour les processus fronto-limbiques chez des individus en bonne santé. Dans la première étude, l'association entre l'humeur au quotidien (évaluée à l’aide de la méthode de journal quotidien) et les processus cérébraux a été étudiée. Dans la deuxième étude, l'association entre la méthylation périphérique du gène du transporteur de la sérotonine [SLC6A4] (liée au fonctionnement émotionnel), provenant de différents tissus, et les processus cérébraux a été étudiée. Dans la troisième étude, nous avons examiné si l'association entre la méthylation périphérique du gène SLC6A4 et les processus cérébraux était indépendante de la variation génétique (en utilisant un échantillon de jumeaux homozygotes). Sommairement, l'humeur négative et positive était positivement associée à la connectivité fonctionnelle au repos entre le cortex cingulaire postérieur et antérieur. La méthylation du gène SLC6A4 était positivement associée au volume cortical préfrontal lorsqu'elle était dérivée du sang, de la salive et des cellules buccales. La méthylation du gène SLC6A4 dérivée des cellules buccales était également positivement associée au volume cortical antérieur cingulaire et à la connectivité fonctionnelle au repos entre les régions pariétales et le cortex cingulaire antérieur. Aussi, la méthylation périphérique du gène SLC6A4 était positivement associée à l'activité corticale orbitofrontale ainsi qu'à la connectivité fonctionnelle entre l’amygdale, le cortex orbitofrontal et le cortex cingulaire antérieur en réponse à des stimuli émotionnels négatifs, indépendamment de la séquence d'ADN des individus. Dans l'ensemble, les résultats actuels pourraient indiquer que la fonction et la structure cérébrale dans les régions fronto-limbiques, particulièrement dans le cortex cingulaire antérieur et préfrontal, sont positivement associées à l'humeur dans la vie quotidienne et à la méthylation périphérique du gène SLC6A4 chez des individus en bonne santé. En outre, la relation entre ces processus fronto-limbiques et la méthylation périphérique du gène SLC6A4 serait largement sous influence de l’environnement. Aussi, les résultats actuels suggèrent que les cellules buccales constitueraient un tissu préférable pour étudier la méthylation du gène SLC6A4 et les processus neuraux apparentés. Des études supplémentaires sont nécessaires pour valider ces résultats auprès de populations cliniques ou chez les individus exposés à des conditions environnementales différentes.Neural alterations have been observed in the frontal-limbic circuitry (including the prefrontal cortex, the anterior cingulate cortex, the hippocampus and the amygdala), densely innervated with serotonin, in the individuals with affective disorders. Relationship between the frontal-limbic processes and emotional well-being is affected by the genetics and the environment as well as by their interaction (GxE). Yet, the specific mechanisms are not known to this day. The aim of the present thesis was to study the environmental effects on and the relevance of DNA methylation (a physiological mechanism underpinning the GxE influences on gene expression) for the frontal-limbic brain processes in healthy individuals. In the first study, association between the daily-life mood (assessed using a daily diary method) and the brain processes was studied. In the second study, association between the peripheral DNA methylation in the serotonin transporter [SLC6A4] gene (linked to emotional functioning), derived from different tissues, and the brain processes was examined. In the third study, we examined whether the association between the peripheral SLC6A4 gene methylation and the brain processes was independent of the genetic variation (using a monozygotic twin sample). Briefly, daily-life negative and positive mood was positively associated with the resting-state functional connectivity between posterior and anterior cingulate cortices. The SLC6A4 gene methylation was positively associated with the prefrontal cortical volume when derived from blood, saliva and buccal cells; buccal-derived SLC6A4 gene methylation was also found to be positively associated with the anterior cingulate cortical volume and the resting-state functional connectivity between parietal areas and the anterior cingulate cortex. The peripheral SLC6A4 gene methylation was also positively associated with the orbitofrontal cortical activity as well as with the functional connectivity between the amygdala, the orbitofrontal and the anterior cingulate cortices in response to negative emotional stimuli, regardless of individuals’ DNA sequence. Overall, current findings might indicate that brain function and structure in the frontal-limbic regions, particularly in the anterior cingulate and the prefrontal cortices, are positively associated with the daily-life mood and the peripheral SLC6A4 gene methylation in healthy individuals. Additionally, the relationship between these frontal-limbic processes and peripheral SLC6A4 gene methylation appear to be largely driven by the environmental influences. Also, current results suggest that buccal cells may be a suitable peripheral tissue for studying the SLC6A4 gene methylation and its related neural processes. Future studies are necessary to validate these results in the clinical population as well as in the individuals exposed to differential environmental conditions

The role of emotions and physiological arousal in modulating impulsive behaviour.

Impulsivity received considerable attention in the context of drug misuse and certain neuropsychiatric conditions. Because of its great health and well-being importance, it is crucial to understand factors which modulate impulsive behaviour. As a growing body of literature indicates the role of emotional and physiological states in guiding our actions and decisions, we argue that current affective state and physiological arousal exert a significant influence on behavioural impulsivity. As 'impulsivity' is a heterogeneous concept, in this paper, we review key theories of the topic and summarise information about distinct impulsivity subtypes and their methods of assessment, pointing out to the differences between the various components of the construct. Moreover, we review existing literature on the relationship between emotional states, arousal and impulsive behaviour and suggest directions for future research

Resting-State Functional Connectivity between Fronto-Parietal and Default Mode Networks in Obsessive-Compulsive Disorder

Background: Obsessive-compulsive disorder (OCD) is characterized by an excessive focus on upsetting or disturbing thoughts, feelings, and images that are internally-generated. Internally-focused thought processes are subserved by the ‘‘default mode network’ ’ (DMN), which has been found to be hyperactive in OCD during cognitive tasks. In healthy individuals, disengagement from internally-focused thought processes may rely on interactions between DMN and a frontoparietal network (FPN) associated with external attention and task execution. Altered connectivity between FPN and DMN may contribute to the dysfunctional behavior and brain activity found in OCD. Methods: The current study examined interactions between FPN and DMN during rest in 30 patients with OCD (17 unmedicated) and 32 control subjects (17 unmedicated). Timecourses from seven fronto-parietal seeds were correlated across the whole brain and compared between groups. Results: OCD patients exhibited altered connectivity between FPN seeds (primarily anterior insula) and several regions of DMN including posterior cingulate cortex, medial frontal cortex, posterior inferior parietal lobule, and parahippocampus. These differences were driven largely by a reduction of negative correlations among patients compared to controls. Patients also showed greater positive connectivity between FPN and regions outside DMN, including thalamus, lateral frontal cortex, and somatosensory/motor regions

Multimodal MRI of grey matter, white matter, and functional connectivity in cognitively healthy mutation carriers at risk for frontotemporal dementia and Alzheimer's disease

Background: Frontotemporal dementia (FTD) and Alzheimer's disease (AD) are associated with divergent differences in grey matter volume, white matter diffusion, and functional connectivity. However, it is unknown at what disease stage these differences emerge. Here, we investigate whether divergent differences in grey matter volume, white matter diffusion, and functional connectivity are already apparent between cognitively healthy carriers of pathogenic FTD mutations, and cognitively healthy carriers at increased AD risk. Methods: We acquired multimodal magnetic resonance imaging (MRI) brain scans in cognitively healthy subjects with (n=39) and without (n=36) microtubule-associated protein Tau (MAPT) or progranulin (GRN) mutations, and with (n=37) and without (n=38) apolipoprotein E ϵ4 (APOE4) allele. We evaluated grey matter volume using voxel-based morphometry, white matter diffusion using tract-based spatial statistics (TBSS), and region-to-network functional connectivity using dual regression in the default mode network and salience network. We tested for differences between the respective carriers and controls, as well as for divergence of those differences. For the divergence contrast, we additionally performed region-of-interest TBSS analyses in known areas o