Gait Mate: Examining Neural Networks Engaged During Lower Extremity Movement in the MRI

Less than 50% of stroke survivors progress to independent community ambulation. Even among the stroke survivors who achieve independent ambulation, significant residual deficits persist in balance and gait speed, with 60% of persons post-stroke reporting limitations in mobility related to walking.Consequently maximizing recovery of locomotor function is the focus of neurorehabilitation efforts worldwide. A recently completed clinical trial from members of this investigative team demonstrated that 6 weeks of treadmill training elicits substantial improvements in over ground walking speed and symmetry in persons following stroke. Consistent with the goals of the South Carolina Stroke Rehabilitation Research Center (SCSRRC) and NIH Brain Initiative, the investigators now plan to investigate the effects treadmill-assisted gait training have on cortical control of bipedal movement in chronic stroke patients. Although previous investigators have assessed neural activity during simulated walking using motor imagery, motor imagery does not simulate the typical sensory feedback associated with active movement. To move the field forward, it is necessary to measure active bipedal movement in the MR-environment in healthy volunteers, before moving forward in stroke patients.

The overarching goal of this Discovery Proposal is to evaluate neural activity during unipedal and bipedal movement in a cohort of healthy individuals (Aim 1).

The rigor and reproducibility will be evaluated by comparing the results of 1) active movement -Bipedal with 2) active movement -unipedal 4 and 3) imagined movement.

Dependent measures include: 1) head motion during the fMRI task, 2) BOLD signal in the ipsilateral and contralateral motor cortex during the fMRI task, 3) force applied during the fMRI task, and 4) participant feedback using a modified version of the Presence Questionnaire (a standard tool to assess ecological validity of virtual environments.

Each Aim has a development and evaluation aspect. Through this 1 year proposal the investigators will determine if the bipedal fMRI protocol (active movement) is able to engage neural networks more robustly (e.g. greater effect size) than bipedal imagery alone in Healthy Volunteers.

Specific Aim #1: Healthy volunteers: The investigators will test the hypothesis that with active bipedal movement there will be 1) no difference in head movement, but 2) greater motor cortex BOLD signal, 3) smoother force exchange between the feet, 4) higher participant satisfaction than unipedal movement or motor imagery alone. This sample size was selected based on a prior publication of imagined movement. The outcome of this aim may result in the first publication in the field to evaluate bipedal movement in an MR-environment.

Eligibility Criteria:
Inclusion criteria:

* Age 21-65
* Right hand dominant
* Able to read and understand questionnaires and informed consent

Exclusion criteria:

* Self reported history of cardiac disease, COPD or oxygen dependence, neurological and psychiatric disorders, dementia or previous stroke, major head trauma, severe visual impairment, osteoarthritis, orthopedic problems that limit passive range of motion, illegal drug or alcohol dependence, claustrophobia
* Non-mri compatible metal implants in the body
* Pregnant females