Ongoing Research Projects

Cortical mechanisms underlying postural control in chronic stroke survivors.

According to the Center for Disease Control and Prevention, there are nearly 7 million stroke survivors in the United States. About 30% of stroke survivors experience falls. Up to 75% of individuals experience a fall in the 6 months following discharge from hospital. In addition to the financial burden, falls and the resulting fear of new falls tend to reduce physical activity, restrict participation in social activities, and reduce independence in activities of daily living (ADLs), thus negatively influencing the quality of life. Therefore, it is important to reduce the incidence of falls in stroke patients to improve their quality of life. Balance control is an important factor contributing to falls in stroke patients. Importantly, balance control has been found to be an indicator of mobility and independence in ADLs. Therefore, there is a critical need to design novel and effective interventions to improve balance control in stroke patients. We study the neural network underlying balance control in individuals with stroke using high resolution electroencephalography and determine whether this network can be modulated using non-invasive brain stimulation in these patients. Our findings could lead to effective neuromodulation strategies and innovative closed-loop BMI-robotics to improve balance control in stroke patients, thus leading to a reduce rate of falls.

An objective assessment of hand function in children.

Current clinical tests of dexterity in children focus on assessing the time or speed to complete a functional task and/or provide a subjective information on the quality of movement. However, such measures fail to quantify the quality of movement. Mainly, these measures fail to provide information on the sensorimotor control of forces exerted on an object. We have developed a new pediatric dexterity test, the Bead Maze Hand Function test, that provides an objective assessment of manual performance that depends on the integration between sensory information and motor command.

Cortical mechanisms underlying conditional visuomotor learning in young and older adults.

Certain assistive strategies such as the use of color coding, e.g. color-coded burners and knobs, could effectively enhance independence, self-sufficiency, and quality of life of older individuals, thus prolonging care at home. These color cues have been found to be more effective than pharmacological interventions in reducing physical and cognitive impairment in older adults. However, the effectiveness of color coding as an assistive strategy relies on the ability of older adults to learn to associate color cues to motor responses through arbitrary rules, i.e., conditional learning. Older adults have been found to be impaired in forming new arbitrary sensorimotor mappings. Thus, impaired conditional learning can interfere with the use of color coding as an assistive strategy, and lead to using of alternative, but costlier interventions such as drugs. To assist older adults in gaining independence in performing ADL, it is important to understand the sensorimotor and cognitive mechanisms underlying conditional learning and how these mechanisms change with age.In order to determine the fundamental mechanisms underlying conditional learning and how these mechanisms are affected with aging, we developed a novel conditional visuomotor task. By combining this novel task with transcranial magnetic stimulation (TMS), we found that PMd is involved with the monitoring the object tilt following the application of digit forces. Our current work is looking at the contributions of primary motor cortex and dorsolateral prefontal cortex to specific stages of conditional learning. Our findings will elucidate the contribution of cortical areas to conditional visuomotor learning and the mechanisms underlying impaired conditional visuomotor learning in older adults. This new knowledge will lay the foundation for future studies geared at improving conditional learning in neurological conditions whose occurrence is a function of aging, e.g. Alzheimer’s disease.

Variability in neural activity during motor planning.

While holding a coffee mug filled to the brim, we strive to avoid spilling the coffee. This ability relies on the interaction between the control of finger forces on a moment-to-moment basis and the visual information about the object. Such sensorimotor interaction is affected in patients with stroke, Parkinson’s disease, and cerebral palsy. Studies investigating force control have shown that fluctuations in the exerted force are not mere noise but arise from systematic physiological processes. Most recent evidence points toward a link between neural activity within the fronto-parietal brain regions including primary motor cortex (M1) and the fluctuations in grip force. We are understanding specific contributions of the cortical activity to regulation of grip force.