Dorsolateral prefrontal cortex (DLPFC) has been found to be involved in cognitive functions such as executive function, response selection, and working memory. By applying transcranial magnetic stimulation (TMS) or transcranial focused ultrasound (FUS), which is a technology to temporally alter brain state in the stimulation site, the investigators aim to find supporting evidence for the causal relationship between the targeted stimulation site and motor learning improvement or response selection.

The purpose of this study is to test the functions of dorsolateral prefrontal cortex in human motor learning. Dorsolateral prefrontal cortex (DLPFC) has been found to be involved in cognitive functions such as executive function, response selection, and working memory. Recent Findings hint potential involvement of dorsolateral prefrontal cortex in motor learning. Rare studies provided supporting evidence on its involvement and functions. This study aims to examine the functional roles of dorsolateral prefrontal cortex in human motor learning. By applying transcranial magnetic stimulation (TMS) or transcranial focused ultrasound (FUS), which is a technology to temporally alter brain state in the stimulation site, the investigators aim to find supporting evidence for the causal relationship between the targeted stimulation site and motor learning improvement or response selection.

Young healthy adults will be recruited and randomly assigned to one of four experimental groups. If randomized into one of the TMS groups, participants will learn to adapt to two visual rotations (20 and 60 degrees) when reaching for a virtual target, subjects will receive repetitive TMS (rTMS) stimulation over the targeted location, left DLPFC, or right DLPFC depending on the study group. How rTMS stimulation influencing the acquisition and retention of motor memory will be assessed based on group comparison of behavioral measures such as reaching accuracy. If randomized into the FUS group, participants will complete a flanker task to focuses on the assessment of response selection and inhibitory control.

Inclusion Criteria:

• Healthy, adult subjects
• 18 to 35 years of age
• Right-handed
• Have no any type of metal in the body
• Provide written informed consent

Exclusion Criteria:

• Presence of a significant medical, psychiatric, or neurologic illness
• History of loss of consciousness of more than ten minutes in the past year or loss of consciousness in a lifetime that required rehabilitation services
• Personal or family history of seizure
• Any history of stroke/transient ischemic attack (TIA) or severe traumatic brain injury
• Taking any medications that may decrease the threshold for seizure
• Pregnancy (self-reported)
• Affirmative answers to one or more questions of the provided attached safety questionnaires. These are not absolute contraindications to this study but the risk/benefit ratio will be carefully balanced by the PI
• Failure to follow laboratory or study procedures

Participants receiving ultrasound stimulation will be blinded to the type of ultrasound stimulation they are receiving.