This study's objective is to determine if electrical stimulation can safely reduced atrial fibrillation, which is an abnormal heart rhythm that begins in the top chambers of the heart. Electrical stimulation will be delivered to the wrists or in the ear. Participation will last about 6 weeks and require 3 clinic visits. Participants will be asked to wear a heart monitor and patch to monitor the heart rate and rhythm, keep a diary to collect information on atrial fibrillation, undergo randomization (being randomly assigned, like drawing straws) and use the study device per randomization assignment. Participants are randomized in a 1:1:1 fashion to a wrist worn study device, an ear piece study device or a sham wrist worn study device. A sham device looks like the real wrist worn device but does not deliver any electrical stimulation.

The purpose of this study is to examine the relationship between reflexes in the leg and the presence of neuropathic pain. The researchers are recruiting 30 individuals with spinal cord injury (SCI) total, 15 individuals with neuropathic pain due to SCI and 15 individuals without neuropathic pain. For this portion of the study, there are 2 visits. The first visit will examine cutaneous reflexes in the leg. During the second visit, the study team will assess sensation in the leg and administer questionnaires about pain, functioning, and quality of life.

The purpose of the second part of the study is to examine the effect of reflex training in the leg to decrease neuropathic pain. For this, the researchers are recruiting 15 individuals with neuropathic pain due to spinal cord injury to participate in the reflex training procedure. The study involves approximately 50 visits with a total study duration of about 6.5 months (3 months for baseline and training phases followed by 1 month and 3 month follow-up visits).

Rehabilitation interventions including resistance training, functional and task-specific therapy, and gait or locomotor training have been shown to be successful in improving motor function in individuals with neurologic disease or injury. Recent investigations conducted in our laboratory indicate that intense resistance training coupled with task-specific functional training lead to significant gains in functional motor recovery. Similarly, gait rehabilitation involving intense treadmill training and/or task-specific locomotor training has been shown to be effective in improving locomotor ability. However, the underlying neural adaptations associated with these therapeutic approaches are not well understood. Our primary goal is to understand the motor control underpinnings of neurologic rehabilitation in order to apply this knowledge to future generations of therapeutic interventions.