BME Seminar Series: Dr. Wilsaan Joiner, University of California

Wilsaan M. Joiner, PhD
Associate Professor
Department of Neurobiology, Physiology and Behavior, College of Biological Sciences
Department of Neurology, School of Medicine
University of California, Davis

Abstract: 

"Dynamic sonomyographic imaging provides potential control signals for upper-extremity prosthetics"

Patients with upper limb differences often cite difficulty of use as a key contributing factor for abandoning their prosthesis, creating a pressing need for an improved control methodology. A major challenge of using traditional surface electromyography electrodes has been the difficulty in achieving intuitive and robust proportional control of multiple degrees of freedom. To address this problem, our group is refining a control method (sonomyographic control) that senses muscle mechanical deformations using ultrasound. In this way the resulting control signals can directly control the position of the end effector. Compared to myoelectric signals which control end-effector velocity, sonomyographic control is more congruent with the remaining proprioception within the residual limb. In addition, ultrasound imaging can non-invasively resolve individual muscles, including those deep inside the tissue, and detect dynamic activity within different functional compartments in real-time. This alignment between activation and proprioception, as well as the ability to distinguish small, but significant differences in deep muscle tissue activations (e.g., different grasp patterns) may collectively provide more intuitive control signals for prosthetic devices. Recently, we tested our control method with upper-extremity amputees and able-bodied subjects. Both amputee and control subjects with no prior experience of using a sonomyography-based interface were able to demonstrate fine graded control of an end-effector controlled by muscle activation patterns in the forearm. In a subsequent study with control subjects we tested the extent vibrotactile haptic feedback improved this control. The results show that subjects made large errors when visual feedback was removed, but precision improved in the presence of haptic feedback, almost reaching the performance level observed when visual feedback was available. Together, our results demonstrate the potential of using sonomyographic signals for intuitive dexterous control of multiarticulated prostheses. In addition, this method may have potential basic science applications including fundamental investigations of motor learning and control.

Bio:

Dr. Wilsaan Joiner’s research group conducts translational research in healthy individuals and clinical conditions such as Schizophrenia, Alzheimer's Disease, and patients with upper limb differences. The group uses various experimental techniques (e.g., fMRI, eye tracking, motion capture, human psychophysics) and approaches (e.g., robotics, behavioral neuroscience and computational modeling) to investigate the integration of sensory and motor signals, and the role these signals play in guiding goal-directed movements, visual perception, motor adaptation and memory consolidation. Dr. Joiner obtained his PhD in Biomedical Engineering from the Johns Hopkins University School of Medicine, and was a postdoctoral fellow at Harvard University and the National Eye Institute. He was awarded the NIH Pathway to Independence Award (K99/R00) from the National Eye Institute and was the recipient of an NSF CAREER Award under the Biomedical Engineering Program. Before joining the departments of Neurobiology, Physiology and Behavior; and Neurology at UC Davis, Dr. Joiner was an assistant professor in the Bioengineering Department at George Mason University. At George Mason Dr. Joiner was the recipient of a Mentoring Excellence Award and the Emerging Researcher/Scholar/Creator Award. His current research is funded by several grants from the Alzheimer's Association, National Science Foundation and the National Institutes of Health.