The goal of this interventional study is to learn the effects that stimulant medication prescribed to ADHD individuals has in their performance of attentive tasks, as measured by images and data collected through neuroimaging (fMRI) while also implementing new motion-correcting software. The main questions it aims to answer are:

1. How do the use of stimulants affect brain activity and motion in fMRI research in ADHD studies?
2. Can neurofeedback, an attentive task using real-time brain activity, engage the same brain circuits as seen with stimulant medication in individuals with ADHD?

Researchers will compare participant's brain activity from the completion of attentive tasks performed in the scanner while following their regular medication regimen and while abstaining to take medication. Researchers will also compare how the data collected using a more precise motion correction software differs to other previously reported data from ADHD studies who possibly employed more lenient measures of motion correction.

Participants will:

1. Be asked to complete at least 4 fMRI sessions, two of which will include neurofeedback
2. Be asked to abstain from taking stimulant medication on the day of two of these fMRI visits
3. Complete attentive tasks while in the scanner that will activate target brain regions of interest

Inclusion Criteria:

• Age 12 or older
• Able to follow verbal and written instructions in native language
• Pre-existing clinical ADHD diagnosis (with or without comorbid anxiety diagnoses)
• Pre-existing medication regimen of methylphenidate or amphetamine salt derivatives with no changes in the last month

Exclusion Criteria:

• Known visual impairment preventing test administration
• Contraindication of inability to participate in fMRI scanning (per MRI screening form)
• Known, self-reported non-incidental structural brain abnormality
• Autism Spectrum Disorder or Obsessive-Compulsive Disorder
• Non-verbal

The study population will be largely recruited through the Boston Children Hospital's resources, such as a participant registry or from clinical practice, only applicable to individuals who fit the eligibility criteria listed above.