Design and Evaluation of a Powered Lower-Extremity Exoskeleton
Effective treatment of pathological walking patterns in children with CP is critical to maintaining mobility into adulthood, and powered exoskeletons provide an as-of-yet untapped resource for intervention. While sophisticated wearable robotics and powered exoskeletons are increasingly available to restore function after paralysis in adults, translation of these technologies to children is scarce. The multiple contributors to gait deficits in CP, including spasticity, contracture, muscle weakness and poor motor complicate the design, control, and application of these devices challenging in this population.
The objective of this project is to evaluate a novel exoskeleton designed specifically for use in children with cerebral palsy (CP). The modular exoskeleton is based on the framework of a standard knee-ankle-foot orthosis, yet it provides powered assistance at the knee and a passive assistive device at the ankle. The exoskeleton can also incorporate surface functional electrical stimulation (FES) to aid in muscle activation and timing during walking. We will evaluate the exoskeleton over multiple sessions in our laboratory to assess the effects of robotic assistance on kinematics, kinetics, and muscle activity and to better optimize control strategies for providing gait assistance and rehabilitation to children with CP.
Dopamine and Motor Learning in Cerebral Palsy
The broad objective of this study is to determine the relationship between variations in genes related to dopamine (DA) neurotransmission in areas of the brain associated with motor leaning (e.g. DRD1, DRD2, DRD3, COMT, DAT) and/or to activity-dependent brain plasticity (e.g. BDNF) and differences in motor learning rates and cognitive processing abilities in persons with and without cerebral palsy (CP). We will also explore whether motor and cognitive learning abilities are correlated within individuals which could suggest similar underlying neural mechanisms. Finally we would like to evaluate the effect of rewards on procedural learning in those with and without CP, to preliminarily assess how behavioral manipulations of the DA system may affect learning.
This protocol will consist of an observational trial whereby subjects with and without CP will participate in two different training paradigms, one that involves learning novel working memory tasks and one that involves motor skill learning in the lower extremities. All will have blood draws for genetic analyses at baseline, the results of which will be related to changes in performance (learning) per task after training. A second part will be a within-subjects evaluation on the effects of reward (versus no-reward) during learning, which is presumed to increase dopamine transmission.
Correlation of Cortical Sources and Muscle Synergies during Walking
A prevailing question in human motor control is how the nervous system is able to efficiently and effectively harness the bodies many degrees of freedom to achieve a wide variety of complex movements, such as walking.
One theory is that rather than control individual muscles, the nervous system is able to recruit groups of muscles, termed muscle synergies or modules, to simplify the control problem and create functional building blocks to create complex movements. The objective of this project is utilize noninvasive electroencephalography (EEG) in combination with motion capture and electromyography (EMG) to identify correlations between synergies extracted from peripheral muscles with cortical sources measured by EEG.
Functional Near-Infrared Spectroscopy (fNIRS) to Assess Brain Activity in Children and Adults with Movement Disorders
Neural imaging during movement has become more portable by utilizing an approach termed functional near-infrared spectroscopy (aNIRS) as a means to isolate areas of brain activity. fNIRS is a non-invasive imaging technology that uses low levels of nonionizing red and near-infrared colored light to measure the hemodynamic state of the brain.
Although use of these technologies for assessing cortical activation patterns is increasing, validation of these approaches, particularly in children and those with brain injuries such as cerebral palsy, is in the early stages. In this protocol, our objective is to systematically compare cortical activation patterns associated with specified motor and sensory tasks in healthy children and adults to those with unilateral or bilateral childhood-onset neurological injury; The results of this study are expected to increase knowledge of brain activation patterns across tasks and groups with and without brain injuries and to provide for future clinical studies with these technologies.
User-driven (active) Speed control of Treadmill Walking
We have developed an active treadmill that automatically adjusts to the user’s walking speed in real time, thereby providing a more engaging experience than typical treadmill passive treadmill training.
Using electroencephalography (EEG), we compared cortical activity from healthy individuals during a speed tracking task using the active and passive treadmills. The results showed increased activity during the active treadmill task, not only in the motor cortex but also in the prefrontal and posterior parietal areas, indicating that the active treadmill more fully engaged the user in the task.
We therefore hypothesize that inclusion of active control in gait training can expedite motor recovery. We plan to evaluate this hypothesis in a randomized controlled trial of children with cerebral palsy. We are also continuing development of more interactive active treadmill training paradigms, including integration of virtual reality.
Rigid Body Database
Protocol # 90-CC-0168
The purpose of this study is to develop a novel method utilize motion capture technology to accurately and precisely quantifying the different ways people control limb and whole body movements.
This information will be used to develop a database on normal movements and adaptive movements of people who have diseases that affect the way they move. The database will serve as a tool to improve diagnosis and treatment of patients with movement-related problems.
Electrical activity in the muscles also may be measured, using small metal electrodes attached to the surface of the skin with an adhesive bandage.
Virtual Functional Anatomy
Despite the frequency of reported joint, muscle, and bone pain among athletes and non-athletes alike, there is still a lack of specificity in determining the cause of this pain . This leads to confusion when designing a treatment plan and to difficulty in assessing the efficacy of interventions. Broad categories are often too quickly accepted as a diagnosis without the underlying root causes being fully understood. With the advent of new imaging technologies allowing the non-invasive study of in vivo muscle and skeletal dynamics during volitional tasks, we have an opportunity to revisit these broad classifications in order to develop more specific measurements that can be correlated with specific impaired joint structures. This ability in turn, will allow for improved joint pathology diagnoses, treatments, and eventually clinical outcomes.
This study uses magnetic resonance (MR) and ultrasound imaging to study how muscles, tendons, and bones work together to cause motion. The procedure is one of several tools being developed to characterize normal and impaired joint and muscle function, with the goal of developing improved methods of diagnosis and treatment of movement disorders. Healthy normal volunteers from age 5 to unlimited, with or without joint impairment, may be eligible for this study. The current focusses of this protocol are on the changes to knee joint shape and muscle volume throughout the adolescent years, ACL injury, and patellofemoral (kneecap) pain in both the adolescent and adult.
Muscle Strength Loss and Its Effect on Knee Cap Motion in Volunteers With Anterior Knee Pain
Chronic patellofemoral (kneecap) pain, a potential precursor to osteoarthritis, is one of the most common problems of the knee. It is characterized by pain at, behind, or around the knee cap that is aggravated by deep knee flexion, prolonged sitting, and repetitive flexion/extension. Clinically, it is most often assumed that this pain is due to a muscle force imbalance that leads to knee malalignment and maltracking. In turn, this malalignment and maltracking leads to elevated joint stresses, which ultimately leads to knee cap pain. Recent work has shown that altered force balance around the knee can indeed lead to maltracking. However, the question remains whether correcting an existing force imbalance around the knee can normalize knee cap motion and/or reduce pain. The purpose of this study is to determine how temporary loss of force in the vastus lateralis muscle using a nerve block alters the patellar maltracking in subjects with chronic idiopathic patellofemoral pain.
Individuals between 18 to 55 years of age who have knee cap pain that cannot be explained by a specific injury or disease are welcome to participate. Participants will be screened with a physical exam and medical history. This study requires two visits. Each visit will use standard MRI sequences to take images of the knee in motion and at rest. On the first visit, the MRI scan will look at the knee in its natural state. Participants will move the knee up and down for 1 to 3 minutes at a time during the scan. On the second visit, a local anesthetic agent will be injected into the muscle of the thigh. The anesthetic will block this muscle from generating force for 2 or 3 hours. Participants will move the knee up and down for 1 to 3 minutes at a time during the MRI scan.