Project Summary Attention deficit hyperactivity disorder (ADHD) stands as the most prevalent neurodevelopmental disorder, affecting between 5-10% of children worldwide. Over the past two decades, the diagnosis rate for childhood ADHD have surged, resulting in a substantial societal and economic burden on those impacted individuals, their families, and the broader community. ADHD is characterized by compromised cognitive control, yielding adverse life-long consequences for academic and social functioning. Cognitive theories of ADHD have hypothesized that deficiencies in cognitive control and motivational systems might underlie behavioral problems in ADHD. Modern perspectives in neuroscience underscore the latent dynamics of brain as pivotal for comprehending both functional and dysfunctional cognitive processes. The proposed research undertakes the investigation of intricate interplay between intrinsic brain mechanisms, task-modulated brain dynamics, and behavioral and clinical symptoms associated with ADHD. The study has three main aims. The first aim is to examine the intrinsic brain dynamics within the cognitive control and reward systems in children with ADHD, and how aberrant intrinsic brain dynamics might be linked to deficits in functional circuitry when affected children are engaged in cognitively demanding task. The second aim focuses on studying how intrinsic and task-modulated brain dynamics are associated with cognitive control deficits and clinical symptoms in children with ADHD. The third aim involves testing reproducibility and generalizability of the association between brain dynamics and symptoms using datasets collected independently in the United States and Japan. The proposed research significantly augment the scope of the funded parent grant (MH124816) by unveiling the intricate relationship between intrinsic and task-modulated brain dynamics mechanism and their interplay with childhood ADHD. The study capitalizes on multidisciplinary expertise in psychiatry, computational sciences, statistics, cognitive neuroscience, psychology, brain imaging and neurology. Moreover, it builds on our recent studies in developing advanced computational methodologies to solve important problems in cognitive, systems and clinical neuroscience. The ultimate goal of the supplement proposal is to propel our understanding of the foundational neural mechanisms underpinning childhood ADHD. The findings will facilitate developing more targeted and efficient interventions for childhood ADHD in the future. Our cognitive, neuroscience and computational framework developed here can be widely applied to study many psychiatric disorders that manifest similar cognitive deficits, such as schizophrenia and autism.