This research project is examining the effects of noninvasive brain stimulation on human memory. This study will help to better understand noninvasive brain stimulation techniques that may have the potential to aid in memory dysfunction. Subjects will undergo a magnetic resonance imaging (MRI) and a computed tomography (CT) scan, to take pictures of their brain and skull. They will receive noninvasive brain stimulation using low-intensity focused ultrasound (LIFU) sound waves, to temporarily change brain activity. Their brain signals (MRI or EEG) will be monitored to measure changes in their brain signals. Their heart rate, blood pressure, respiratory rate, eye movement and skin moisture will be monitored as well. They will complete neuropsychological batteries and memory tasks. They will complete questionnaires.

This study employs a two-arm, sham-controlled, repeated measures design conducted across eight sessions:

Overall Structure

• Session 1: Baseline Assessment and Imaging
• Session 2-8: LIFU Stimulation *The order of Sessions 2-8 is ideally randomized to control for order effects. The study design allows for flexibility to accommodate varying levels of participant completion while maintaining scientific validity.

Detailed Session Breakdown Session 1: Baseline Assessment and Imaging

• Structural & Functional imaging: MRI and CT anatomical scans
• Administration of questionnaire battery Session 2-8: LIFU Stimulation or Sham
• Memory task performance
• Neuropsychological battery administration
• EEG recording
• Collection of physiological measures (HR, BP, RR, and EDR)

Design Considerations: There will be at least one week between Session 1 and Session 2, and at least 48 hours between each subsequent session. This design allows for within-subject comparisons across stimulation conditions, as well as between-subject comparisons if the full protocol is completed. The study protocol is designed to accommodate potential variability in participant availability. While full completion of all sessions is ideal, partial completion can still yield valuable data.

Inclusion Criteria:

• Subjects of all ethnicities, who understand and speak English.

Exclusion Criteria:

• The exclusion criteria below are regularly implemented in MRI, CT, and EEG experiments for the safety of the subjects and for data quality assurance.

  1. Claustrophobia (scanning environment may be uncomfortable).
  2. Contraindications to MRI: including pacemaker, aneurysm clips, neurostimulators, cochlear implants, metal in eyes, steel worker, or other implants.
  3. Contraindications to CT: pregnancy
  4. Active medical disorder or treatment with potential CNS effects (e.g. Alzheimer's)
  5. History of neurologic disorder. (e.g. Parkinson's, Epilepsy, or Essential Tremor)
  6. History of head injury resulting in loss of consciousness for >10 minutes.
  7. History of alcohol or drug dependence (through self-report).