The field of cognitive neuroscience has benefited greatly from multimodal investigations of the human brain, which integrate various tools and neuroimaging data to understand brain functions and guide treatments for brain disorders. In this dissertation, we present a series of studies that illustrate the use of multimodal approaches to investigate brain structure and function, brain connectivity, and neuromodulation effects. Firstly, we propose a novel landmark-guided region-based spatial normalization technique to accurately quantify brain morphology, which can improve the sensitivity and specificity of functional imaging studies. Subsequently, we shift the investigation to the characteristics of functional brain activity due to visual stimulations. Our findings reveal that the task-evoked positive blood-oxygen-level dependent (BOLD) response is accompanied by sustained negative BOLD responses in the visual cortex. These negative BOLD responses are likely generated through subcortical neuromodulatory systems with distributed ascending projections to the cortex. To further explore the cortico-subcortical relationship, we conduct a multimodal investigation that involves simultaneous data acquisition of pupillometry, electroencephalography (EEG), and functional magnetic resonance imaging (fMRI). This investigation aims to examine the connectivity of brain circuits involved in the cognitive processes of salient stimuli. Using pupillary response as a surrogate measure of activity in the locus coeruleus-norepinephrine system, we find that the pupillary response is associated with the reorganization of functional brain networks during salience processing. In addition, we propose a cortico-subcortical integrated network reorganization model with potential implications for understanding attentional processing and network switching. Lastly, we employ a multimodal investigation that involves concurrent transcranial magnetic stimulation (TMS), EEG, and fMRI to explore network perturbations and measurements of the propagation effects. In a preliminary exploration on brain-state dependency of TMS-induced effects, we find that the propagation of left dorsolateral prefrontal cortex TMS to regions in the lateral frontoparietal network might depend on the brain-state, as indexed by the EEG prefrontal alpha phase. Overall, the studies in this dissertation contribute to the understanding of the structural and functional characteristics of brain network systems, and may inform future investigations that use multimodal methodological approaches, such as pupillometry, brain connectivity, and neuromodulation tools. The work presented in this dissertation has potential implications for the development of efficient and personalized treatments for major depressive disorder, attention deficit hyperactivity disorder, and Alzheimer's disease.

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A limited amount of research exists that addresses low self-esteem, poor self-concept, and distorted self-image in children with Attention-deficit Hyperactivity Disorder (ADHD). The most urgent task is to test assumptions regarding self-perception and to assess the dimensions of self-concept influenced by this disorder. The Self-Perception Profile for Children (Harter, 1985) was used in the present study to assess those dimensions. Participants included 34 boys with ADHD, 27 boys with LD, and 33 boys without any diagnosed psychological or learning problems. Results were analyzed using Pearson's product-moment correlation, analyses of variance (ANOVA), and analyses of covariance (ANCOVA) and did not support the hypotheses.

Bakgrund: Fysisk aktivitet har visat sig ha en positiv effekt för både den psykiska och fysiska hälsan. Den kan minska psykiska problem som oro, stress och depression, samt fysiska åkommor som blodtryck, stroke och diabetes. Fysisk aktivitet är numera en allt mer vedertagen metod för att behandla fysiska och psykiska besvär. Individer med ADHD har vanligen problem med hyperaktivitet, impulsivitet, uppmärksamhet, sociala beteenden och kognitiva förmågor.Syfte: Att undersöka den vetenskapliga litteraturen för att få belägg för vilka effekter fysisk aktivitet kan ha för symptom hos individer med ADHD.Metod: I denna systematiska litteraturstudie återfanns via sökningar i databaserna PubMed, The Cochrane Library, Web of Science, Science Direct och PsycINFO artiklar som sedan granskades utifrån en bedömningsmall.Resultat: Fysisk aktivitet upplevdes ha en positiv effekt för hyperaktivitet och uppmärksamhetsproblem samt visade sig minska risken för sociala beteendeproblem hos individer diagnostiserade med ADHD. Vidare påvisades att oavsett regelbundenhet eller omfattning av fysisk aktivitet en positiv effekt för kognitiva förmågor hos individer diagnostiserade med ADHD.Konklusion: Den vetenskapliga litteraturen visar att fysisk aktivitet troligen har en positiv effekt för ett flertal symptom hos individer med ADHD. Dock krävs ytterligare forskning i ämnet. / Background: Physical activity has been shown to have a positive impact for both mental and physical health. It may reduce psychological problems such as anxiety, stress and depression, and physical issues like high blood pressure, stroke and diabetes. Physical activity is now an increasingly accepted method to treat physical and mental disorders. Individuals with ADHD usually have problems with hyperactivity, impulsivity, attention, social behavior and cognitive abilities.Aim: To investigate the scientific literature for evidence about the effect of physical activity on symptoms in individuals with ADHD.Method: In this systematic literature review articles where found through the databases PubMed, The Cochrane Library, Web of Science, Science Direct and PsycINFO witch was later surveyed based on an assessment template.Results: Physical activity was perceived to have a positive effect for hyperactivity and attention problems and appeared to reduce the risk of social behavior problems in individuals diagnosed with ADHD. Furthermore, it was shown that regardless of frequency or extent of physical activity a positive effect was shown on cognitive abilities in individuals diagnosed with ADHD.Conclusion: The scientific literature shows that physical activity is likely to have a positive effect for a variety of symptoms in individuals with ADHD. However, further research on the subject is required.

Within the last decade, the influence of focus of attention (FOA) instruction on postural control has been an increased interest among researchers (Yeh et al., 2016; McNevin et al., 2013). The general agreement when it comes to the role of FOA has been that adopting an external (EXT) FOA enhances the efficiency of motor programming by strengthening the relationship between movement planning and outcome, when compared to an internal (INT) FOA (see Wulf, 2013). However, increasing evidence suggests that the benefits from an EXT FOA can be mitigated by certain factors (e.g., age, skill level, novelty of the task and task complexity; Becker & Smith, 2013; Emanuel et al., 2008). As such, questions remain as to what form of FOA instruction is best suited for young learners, as FOA research has been criticized for being studied almost exclusively among adults (Agar et al., 2016). Research in this area is particularly sparse as it pertains to FOA in combination with postural control among this younger age group. This is particularly problematic as significant changes in postural control, stability and balance occur during one’s first decade in life (Haas, et al., 1989; Hay & Redon, 1999; Barela et al., 2003). Moreover, there exists some methodological concerns with regard to the lack of consistency of FOA instructions being used during experimentation. This directly influences where participants are guiding their attention and their interpretation of FOA cues (Davids, 2007; Petranek, et al., 2019). Further, the lack of replicability of traditional FOA studies and the increasing number of non-statistically significant findings in this research, calls into question the overall validity, both internal and external, regarding FOA instruction (Becker & Smith, 2013; Lawrence et al., 2011). Therefore, as a series of four complementary studies, the overall aim of this thesis is to further investigate these theoretical as well as procedural gaps. The first study examines which type of FOA instruction is best suited for two groups of young learners (typically developing children between 4-6 and 7-10 years of age) performing a postural control task. Participants will be randomized into either an INT, EXT or CTRL condition, where they will perform a postural control task with different respective visual displays. A force platform will be used to assess participants’ mediolateral centre of pressure (COP) performance, and electromyography (EMG) will be used to assess muscular activation of the participants’ major ankle stabilizers. The primary goal of study one is to investigate the influence of FOA in children by following the most common and traditional of FOA instruction. The second study serves as an extension for the first study. The aim of this study is to specifically investigate the validity and reliability of using FOA instructions, and whether or not the different attentional cues can drive their intended mental focus states. The method of this study is identical to those is Study 1 with a few major exceptions. In this case, two manipulation checks will be added to the procedure in order to assess how participants perceived, comprehended, and acted to their assigned FOA instructional condition. The first manipulation check is embedded in the structure of the trial itself: the comparison of postural control performance with and without visual information, modeled after the technique used in Yeh and colleagues (2016). The second manipulation check will be a retrospective verbal interview inspired by Perreault & French (2016). Finally, the third and fourth studies look to expand the research question from study one and two to different populations of atypically developing young learners who are known to struggle with both attention and postural control. Individuals with ADHD and individuals with DCD have been shown to interpret attentional and postural information differently when compared to age-matched controls. Therefore, the aim of these studies is to compare the differing effects of FOA across neurodiverse populations. Specifically, study three will use a group of young learners (from 4 – 10 years of age) with ADHD and study four will use a group of young learners (from 4 – 10 years of age) with DCD. The only differences in these studies compared to study one will be the lack of an age split and the use of EMG assessment. / Thesis / Master of Science in Kinesiology

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