The purpose of the first portion of this study is to gather feedback from clinicians on the usability of the current system and procedure, so the researchers can make reflex training more useful and usable for improving recovery after spinal cord injury or other nervous system injuries and diseases. The researchers are recruiting 20 therapists who have been actively practicing physical medicine and 30 adults with no known neurological conditions to test system usability and the reflex operant conditioning protocol. For this portion of the study, there are 5 visits. We will also recruit 15 adults with no neurological injuries, 15 adults with neuropathic pain, and 15 adults with non-neuropathic pain to participate in one visit to provide feedback on sensation caused by stimulating electrodes.

The purpose of the second part of the study is to validate the capacity of the system to change the size of the targeted reflex. For this the researchers are recruiting 25 individuals with chronic incomplete SCI who have spasticity in the leg to participate in the reflex training procedure. The study involves approximately 45 visits with a total study duration of about 6 months.

The study team is recruiting 20 adults with spasticity due to chronic stroke and 20 adults with no neurological injuries for a 4 day study over 1 week. In people with chronic stroke, one of the most common and disabling problems is spasticity (increased muscle tone or muscle stiffness). The purpose of this research study is to examine effects of dry needling on the nervous system (pathways between the muscle, spinal cord, and brain) in people with spasticity due to chronic stroke. Dry needling is a procedure in which a thin, stainless steel needle is inserted into your skin to produce a muscle twitch response. It is intended to release a knot in your muscle and relieve pain.

The total study duration is 4 visits over one week. The first visit will take about 1.5 hours, during which the study team will determine the best electrode placement and create a removeable cast of your arm or leg to aid in placing electrodes in the next visits. The second visit will take about 3 hours, during which dry needling will take place, and the fourth and fifth visits will take about 1.5 hour. During all visits you will be asked to participate in examinations of reflexes (muscle responses to non-invasive nerve stimulation) and arm/leg function.

Older adults typically have trouble identifying the speech they hear, especially in noisy environments. Fortunately, compared to younger adults, older adults are better able to compensate for difficulties identifying the speech they hear by recruiting the visual system. However, the extent to which older adults can benefit from visual input, and how this influence relates to age-related changes in brain structure and function, have not been thoroughly investigated. The general purpose of this study is to determine how age-related changes in brain structure and function affect how well people hear and see. This study seeks participants with normal hearing to mild hearing loss, who also have normal or corrected-to-normal vision.