Modulation of Frontoparietal Dynamics Underlying Adolescent Working Memory Deficits

Patient Arm: We will enroll a sample of adolescents (age 13-18 years) with working memory deficits and ADHD. Participation in this study will not require any adjustments to their clinical care. There are no costs to this study (participants compensated) and there are no expected long-term benefits to the participants. Participants will be compensated for each session. Participants can withdraw from the study at any time. Inclusion Criteria 1. Ability to provide assent and have parent provide parental permission 2. English fluency of the participant and the legal guardian/parent 3. 13-18 years 4. Parent rating on BRIEF-2 Working Memory: Greater than 1.0 SD above normative mean. 5. IQ \> 80 6. Clinical diagnosis of attention deficit hyperactivity disorder (ADHD): predominantly inattentive type, predominantly hyperactive/impulsive type, combined type, or unspecified type. Diagnostic criteria will be confirmed with NICHQ Vanderbilt Assessment Scales-Parent. Healthy Control Arm: We will target a sample of healthy, young adults. Inclusion Criteria 1. Ability to provide consent 2. English fluency of the participant 3. 18-25 years 4. Never diagnosed or meets current criteria for a psychiatric disorder, as measured by self-report of prior diagnoses and formal completion of the diagnostic interview. Exclusion Criteria: For patient and healthy control participants Participants will be screened to exclude individuals with neurological or medical conditions that might confound the results, as well as to exclude participants in whom MRI or TMS might result in increased risk of side effects or complications. Common contraindications include metallic hardware in the body, cardiac pacemaker, patients with an implanted medication pumps or an intracardiac line, or prescription of medications known to lower seizure threshold. These account for the majority of the exclusion criteria listed below: 1. Intracranial pathology from a known genetic disorder (e.g., NF1, tuberous sclerosis) or from acquired neurologic disease (e.g. stroke, tumor), cerebral palsy, history of severe head injury, or significant dysmorphology 2. History of fainting spells of unknown or undetermined etiology that might constitute seizures 3. History of seizures, diagnosis of epilepsy, or immediate (1st degree relative) family history epilepsy 4. Any progressive (e.g., neurodegenerative) neurological disorder 5. Chronic (particularly) uncontrolled medical conditions that may cause a medical emergency in case of a provoked seizure (cardiac malformation, cardiac dysrhythmia, asthma, etc.) 6. Contraindicated metal implants in the head, brain or spinal cord (excluding dental implants, braces or fillings) 7. Non-removable makeup or piercings 8. Pacemaker 9. Implanted medication pump 10. Vagal nerve stimulator 11. Deep brain stimulator 12. TENS unit (unless removed completely for the study) 13. Ventriculo-peritoneal shunt 14. Signs of increased intracranial pressure 15. Intracranial lesion (including incidental finding on MRI) 16. History of head injury resulting in prolonged loss of consciousness 17. Substance abuse or dependence within past six months (i.e., DSM-5 substance use disorder criteria) 18. Chronic treatment with prescription medications that decrease cortical seizure threshold, not including psychostimulant medication if deemed to be medically safe as part of the medical review process. 19. Active psychosis or mania 20. Current suicidal intent 21. Current pregnancy 22. Significant visual, hearing or speech impairment 23. Current wards of the state