Influence of Brain Oscillation-Dependent TMS on Motor Function

* INCLUSION CRITERIA: * Healthy younger adults: * Ages 18 years to less than 50 years. (18 to 49) * Willingness/ability to provide informed consent. * Ability to induce a motor evoked potential in the muscle target of the upper extremity, as evaluated during the TMS Screening. * Healthy older adults: * Age 50 and over * Willingness/ability to provide informed consent. * Ability to induce a motor evoked potential in the muscle target of the upper extremity, as evaluated during the TMS Screening. * Stroke patients: * Age 18 and over. * Unilateral or bilateral upper limb paresis with the ability to voluntarily contract a finger, hand, wrist, or elbow muscle in the affected arm(s). * Stroke onset \> 6 months prior to participation. * Intact M1 sufficient to induce motor evoked potentials in the affected upper extremity following ipsilesional TMS, as evaluated during the TMS Screening. * Willingness/ability to provide informed consent. * If the investigator feels the individual s capacity to provide informed consent is questionable, the NIH Human Subjects Protection Unit (HSPU) will be requested to determine the individual s ability to consent. EXCLUSION CRITERIA: * Healthy younger and older adults: * Presence of severe neurological or medical disorder (e.g., Parkinson s disease or multiple sclerosis). * History of seizures. * Chronic use of antipsychotic drugs (e.g., chlorpromazine or clozapine), tri-cyclic or other anti-depressants, benzodiazepines, or prescription stimulants. * TMS contraindications, such as: * Pacemaker, implanted pump, stimulator, cochlear implant, or metal objects inside the eye or skull. * Diagnosed severe hearing loss. * Current pregnancy. * Staff from our section. * Stroke patients: * Presence of severe neurological or medical disorder, other than stroke (e.g., Parkinson s disease or multiple sclerosis). * History of brainstem stroke. * History of seizures. * Chronic use of antipsychotic drugs (e.g., chlorpromazine or clozapine), benzodiazepines, or prescription stimulants. * TMS contraindications, such as: * Pacemaker, implanted pump, stimulator, cochlear implant, or metal objects inside the eye or skull. ---Diagnosed severe hearing loss. * Current pregnancy. * Staff from our section.