Impact of Sensory Electrical Stimulation on Sensation and Tremor

The purpose of this study is to understand the acute, short-term and long-term impact of transcutaneous and/or percutaneous electrical stimulation with afferent-specific electrical stimulation (asES) on proprioception and fine motor control in the upper extremity. For this purpose, the researchers will use transcutaneous and/or percutaneous asES, high-density electromyography (HD-EMG), arm kinematic measurements, and standardized clinical assessments. This study will be conducted in healthy able-bodied individuals and patients with essential tremor (ET).

Inclusion Criteria for Healthy Participants: * Age from 18 to 80 years, inclusive * No history of a brain and/or skull lesion * Normal hearing and (corrected) vision * Able to understand and give informed consent * No neurological disorders * No tremor * Able to understand and speak English Exclusion Criteria for Healthy Participants: * History of significant head trauma (i.e., extended loss of consciousness, neurological damage) * Known structural brain lesion * Prior neurosurgical procedures * Tremors (as determined by study team) * Co-existence of other neurological diseases * Parkinsonism * Medical (e.g., cardiological, renal, hepatic, oncological) or psychiatric disease that would interfere with study procedures * Pathology that could cause abnormal movements of extremities (e.g., epilepsy, stroke, marked arthritis, etc.) * Inability to perform study tasks or assessments (e.g., follow instructions to stay still during asES procedures) or unable/unwilling to complete study forms * Non-prescribed drug use or recreational marijuana use * History of current substance abuse (exception: current nicotine use is allowed) * Pregnancy * Prisoners Inclusion Criteria for ET Patients: * Age from 18 to 80 years, inclusive * No prior history of skull lesions or craniotomy * Normal hearing and (corrected) vision * Able to understand and give informed consent * Diagnosis of ET (Tremor Research investigation Group criteria) by a physician * At least moderate-severe tremor (based on the TETRAS Tremor Rating Scale) in an upper limb with pure flexion-extension wrist tremor during posture * Stable medication doses for at least 30 days prior to study enrollment and during entire study period * Able to understand and speak English Exclusion Criteria for ET Patients: * History of significant head trauma (i.e., extended loss of consciousness, neurological damage) * Known structural brain lesion * Prior neurosurgical procedures * Mixed or complex tremors (as determined by study team) * Co-existence of other neurological diseases * Parkinsonism * Medical (e.g., cardiological, renal, hepatic, oncological) or psychiatric disease that would - interfere with study procedures * Pathology that could cause abnormal movements of extremities (e.g., epilepsy, stroke, marked arthritis, etc.) * Inability to perform the study tasks or assessments (e.g., follow instructions to stay still during asES procedures) or unable/unwilling to complete study forms * Non-prescribed drug use or recreational marijuana use * History of current substance abuse (exception: current nicotine use is allowed) * Pregnancy * Prisoners