Multifocal HD-tDCS and Motor Function

The purpose of this study is to understand how the brain controls movement and how Non-invasive Brain Stimulation (NIBS) with a technique called High-density transcranial direct current stimulation (HD-tDCS) can alter brain processes to improve behavior. Participants in this study will be randomized to either HD-tDCS with standard intervention or personalized dose-controlled multifocal network-targeted HD-tDCS. The hypothesis is that dexterous hand function will improve after a standard HD-tDCS dose and increase even more after personalized dose-controlled multifocal network-targeted HD-tDCS.

Inclusion Criteria: * Participants should be in good health with normal or corrected-to-normal visual acuity * Right handed * No history of neurological disorder * English speaker * Able to provide written consent prior to admission Exclusion Criteria: * Left-handed * Participants are pregnant, suspect pregnancy or are attempting to become pregnant * Have a pacemaker, intracardiac lines or any other medically implanted device or medicine pump * Have cochlear hearing implants * Taking drugs known to influence neural receptors that facilitate neuroplasticity (see protocol) * Have non removable body piercings or have foreign objects in body * Have metal anywhere in the head that could increase risk of serious injury (not including braces, dental fillings, etc.) (see protocol) * Have a personal or family history of seizure/epilepsy * Taking prescription drugs that lower the threshold for seizures * Recent history of excessive alcohol consumption * History of alcohol addiction/dependence * Recent history of recreational drug use * History of drug addiction/dependence * Recent history of recreational drug use * History of drug addiction/dependence * Diagnosed with a stroke, brain hemorrhage, brain tumor, encephalitis. * Diagnosed with multiple sclerosis * Diagnosed with Parkinson's disease or Alzheimer's disease * Diagnosed with depression in the past 6 months * Diagnosed with attention deficit disorder, schizophrenia, manic depressive (bipolar) disorder * Diagnosed with normal pressure hydrocephalus or increased intra-cranial pressure * Diabetes requiring insulin treatment * Any serious heart disorder or liver disease