Supraspinal control of human locomotion stability

Supraspinal control of human locomotion using mobile electroencephalography (EEG) during terrain negotiation 
  • Led a large study on investigating brain activity during negotiation over uneven terrain using mobile imaging with EEG in young and older adults.​
  • Compared to flat walking, walking over uneven terrain increased theta band power (synchronization), and decreased alpha and beta-band power (desynchronization) near sensorimotor and parietal posterior areas, indicating increased level of visuospatial attention to the environment and greater alertness to balance threat with terrain unevenness.
  • These results will serve as a benchmark for evaluating cortical contribution to mobility deficits in older adults.​
Comparison of EEG source localization using simplified and anatomically accurate head models in younger and older adults [paper]
  • Aim to improve the source localization accuracy for EEG studies by determining the error caused by using simplified head models without individual-specific MRIs in both younger and older adults

Mechanics of locomotion stability

Reactive Balance Control Strategies in Non-Disabled and Post-Stroke Gait [paper]
  • We designed lab-based experiments to understand the mechanics of reactive control strategies in controlling whole-body dynamics in response to trips or slips during walking in both neurotypical and post-stroke individuals.
  • I found that people post-stroke primarily relied on their non-paretic limb to restore balance rather than coordinate both limbs to recover from the forward fall as was observed in neurotypical participants. Proper modulation of ground reaction forces is needed at the paretic side for people post-stroke to reduce the forward rotation of the body. 
Gait Asymmetry and Dynamic Balance 
  • We aims to establish the association between step length asymmetry and dynamic balance. Step length asymmetry is a hallmark of hemiparetic gait in stroke survivors, and alleviating this asymmetry is often a goal of rehabilitation.
  • When people post-stroke walked more symmetrically with biofeedback, their body rotation in the sagittal plane increased rather than decreased.
  • This research may inform existing clinical approaches to reduce heightened destabilization resulting from the reduction of gait asymmetries and further opens the area of research why people post-stroke choose asymmetrical walking patterns.
Foot-placement control strategies during unperturbed and perturbed gait 
  • ​I utilizes system identification techniques to infer the control strategies during loss of balance. I found that people were more sensitive to backward versus forward disturbances.
  • The results could improve the characterization of balance control problems and inform the design of controllers for balance-assisting devices. 

Mechanical assistance for rehabilitation efforts

Dissociating Sensorimotor Recovery and Compensation During Exoskeleton Training Following Stroke [paper]
  • We investigated the interaction between human and robotic assistive devices after brain injury. We found that when using an exoskeleton for upper-extremity training post-stroke, approximately 2/3 of the stroke survivors developed compensatory strategies at the joint level while improving movement smoothness at the end-effector. The work developed novel methods to dissociate true recovery from compensations in subacute stroke survivors by analyzing longitudinal both end-effector and joint kinematic data.