Human-like Robotic Controllers for Enhanced Motor Learning

Inclusion Criteria for Healthy Participants: * Age from 18 to 80 years * No history of a brain and/or skull lesion * Normal hearing and vision, can be corrected * Able to understand and give informed consent * No neurological disorders * Absence of pathology that could cause abnormal movements of extremities (e.g., epilepsy, stroke, marked arthritis, chronic pain, musculoskeletal injuries) * Able to understand and speak English * Height between 3 foot 6 inches (1.1 meters) and 6 foot 2 inches Inclusion Criteria for Participants Post-Stroke: * Age from 18 to 80 years * History of unilateral, supratentorial, ischemic or hemorrhage stroke greater than 6 month * Ability to walk \>10m independently on level ground, allowed to use assistive devices or bracing as needed * Self-selected walking speed is less than 0.8 meters/sec * Medically stable * No concurrent surgeries, medical treatments, participation in research or outpatient therapy * Normal hearing and vision, both can be corrected * Able to understand and give informed consent * Able to understand and speak English * Height between 3 foot 6 inches (1.1 meters) and 6 foot 2 inches Inclusion Criteria for Participants with Spinal Cord Injury: * Age from 18 to 80 years * History of incomplete SCI injury (ASIA C or D) \> 6 months prior * Ability to walk \>10 m independently on level ground, allowed to use assistive devices or bracing as needed * Self-selected walking speed is less than 0.8 meters/sec * Medically stable * No concurrent surgeries, medical treatments, participation in research or outpatient therapy * Normal hearing and vision, both can be corrected * Able to understand and give informed consent * Able to understand and speak English * Height between 3 foot 6 inches (1.1 meters) and 6 foot 2 inches Exclusion Criteria for Healthy Participants: * Weight over 220 lbs * Pregnancy (ruled out by pregnancy questionnaire) * Current presence of wounds or pressure ulcers * Multiple sclerosis, Parkinson's disease or other neurodegenerative disorder, severe dementia, brain injury, spinal cord injury, or cancer of the central nervous system * History of significant head trauma (i.e., extended loss of consciousness, neurological sequelae) * Known structural brain lesion * Significant other disease (heart disease, malignant tumors, mental disorders) * History or peripheral nerve injury * History of sustained non-prescribed drug use or substance abuse (exception: current nicotine use is allowed) * Prior neurosurgical procedures * Inability or unwillingness to perform study-required activities * Prisoners * Unable to meet SRAlab "MRI Pre-Examination Screening Form" requirements Exclusion Criteria for Participants Post-Stroke: * Weight over 220 lbs * Pregnancy (ruled out by pregnancy test) * Botox (botulinum toxin) injection to lower limbs within the prior 3 months, or planned injection during study period. * Current presence of wounds or pressure ulcers * History of sustained non-prescribed drug use or substance abuse (exception: current nicotine use is allowed) * Reduced cognitive function * Severe aphasia * Prisoners * Co-existence of other neurological diseases (e.g., Parkinson's disease or other neurodegenerative disorder, severe dementia, brain injury, spinal cord injury, multiple sclerosis, or cancer of the central nervous system) * History or peripheral nerve injury * Severe hip, knee, or ankle arthritis * Recent fracture or osteoporosis * Significant spasticity in the lower limbs (≥3 on Modified Ashworth Scale) * Medical (cardiac, renal, hepatic, oncological) or psychiatric disease that would interfere with study procedures * Inability or unwillingness to perform study-required activities * Unable to meet SRAlab "MRI Pre-Examination Screening Form" requirements Exclusion Criteria for Participants with Spinal Cord Injury: * Weight over 220 lbs * Pregnancy (ruled out by pregnancy test) * Botox (botulinum toxin) injection to lower limbs within the prior 3 months, or planned injection during study period * Current presence of wounds or pressure ulcers * History of sustained non-prescribed drug use or substance abuse (exception: current nicotine use is allowed) * Prisoners * Co-existence of other neurological diseases (e.g., Parkinson's disease or other neurodegenerative disorder, severe dementia, brain injury, spinal cord injury, multiple sclerosis, or cancer of the central nervous system) * History of peripheral nerve injury * Severe hip, knee, or ankle arthritis * Recent fracture or osteoporosis * Significant spasticity in the lower limbs ( ≥3 on Modified Ashworth Scale) * Medical (cardiac, renal, hepatic, oncological) or psychiatric disease that would interfere with study procedures * Inability or unwillingness to perform study-required activities * Unable to meet SRAlab "MRI Pre-Examination Screening Form" requirements