Research

I have a broad range of interests that ultimately aim to improve the lives of people with disabilities using neural interfaces and prostheses. I am also interested in the mechanisms of how neural interfaces influence the nervous system.

Control of Walking

I am interested in both natural and artificial control of walking. Much of my PhD work aimed to restore walking in a model of spinal cord injury using a spinal cord implant and machine learning. I am also interested in sensorimotor systems and spinal control of walking.

I would like to pursue more research aimed at restoring walking in various injury models, as well as using different neural interfaces and prostheses. I would also like to pursue the control of skilled walking using machine learning.

Images from Dalrymple and Mushahwar 2020,
Dalrymple et al 2020

Implanted Neural Interfaces

I am interested in using implanted neural interfaces to restore function and improve lives. I enjoy characterizing the function of implanted neural interfaces in animal models, but am now working in humans as well. I have experience with intraspinal microstimulation in the lumbar spinal cord, cochlear implants with various electrode coating materials, nerve cuffs, and injectable electrodes.

I am currently working with injectable electrodes (InjectrodesTM) for stimulation of the dorsal root ganglia for pain treatment. I am also part of an early feasibility study for the Stentrode, a stent-based vascular brain-computer interface for communication in locked-in patients. I would like to continue pursuing testing implanted neural interfaces in animal models and humans to assist rehabilitation after neural injury or disease.

Images from Dalrymple and Mushahwar 2020, modified from Shepherd et al 2021, and original artwork.

Neuromodulation

There is a lot of movement in the field of neuromodulation for pain and restoring motor function. I am currently working on a project that uses epidural spinal cord stimulation to restore sensation in lower limb amputees. I am also pursuing non-invasive neuromodulation methods for reducing phantom limb pain in lower limb amputees. Additionally, I am exploring different stimulation waveforms to explore the mechanisms of changes in spinal cord excitability with neuromodulation.

Images from BioRender, TMSi, Axelgaard, and original artwork.

Machine Learning

I aim to continue to use machine learning, where appropriate, throughout my research. I believe that machine learning has an important role to play for controlling neural interfaces and prostheses, medical diagnostics, as well as for characterizing biosignals. I have used supervised machine learning to classify neural activity recorded from the spinal cord of neonatal mice, and supervised and reinforcement learning to control stimulation in the spinal cord for speed adaptable and personalized walking. I am currently funded to explore the use of machine learning to find a biomarker for phantom limb pain in electromyography signals recorded from the residual limb.

Images modified from Dalrymple 2019, Dalrymple and Mushahwar 2020, Dalrymple et al 2020

Current Projects – Carnegie Mellon University
(Continued from University of Pittsburgh)

  • Transcutaneous spinal cord stimulation to reduce phantom limb pain
    • Primary role, funded by NC NM4R pilot grant; NIH
    • Research team: Doug Weber, Lee Fisher
  • Recruitment properties and discomfort of high-frequency transcutaneous spinal cord stimulation
    • Primary role, internally funded
    • Research team: Charli Ann Hooper, Minna Kuriakose, Doug Weber
  • Recruitment of sensory fibers with dorsal root ganglia stimulation using the Injectrode®
    • Primary role, funded by NIH HEAL Initiative
    • Collaboration with Neuronoff, Inc., University of Wisconsin, Case Western Reserve University
    • Research team: Doug Weber, Kip Ludwig, Andrew Shoffstall, Manfred Franke, Stephan Nieuwoudt, Lee Fisher, Jordyn Ting, Rohit Bose
  • Restoring sensation in lower limb amputees using epidural spinal cord stimulation
    • Secondary role, funded by NIH U18
    • Research Team: Lee Fisher, Doug Weber, Eric Helm, Michael Boninger, Marco Capogrosso, Ameya Nanivadekar, Bailey Petersen, Rohit Bose, Dev Sarma, Beatrice Barra
  • Communication and functional independence using the Stentrode Brain-Computer Interface – an early feasibility study
    • Primary role, funded by NIH UG3/UH3
    • Collaboration with Synchron, Mount Sinai University, and the University of Pittsburgh
    • Research Team: Doug Weber, Tom Oxley, David Putrino, Jennifer Collinger, David Lacomis, Adam Fry, Nikole Chetty, Dailyn Despradel, Edward Karst, and others
  • Mechanisms of DRG stimulation
    • Secondary role, supported by Abbott
    • Research Team: Jordyn Ting, Doug Weber, Hyun-Joo Park, Erika Ross
  • Wireless stimulation of the spinal cord using miniature magnetoelectric implants
    • Secondary role
    • Research Team: Jacob Robinson, Joshua Woods, Amanda Singer, Jordyn Ting, Doug Weber

Groups and Collaborators

Former: University of Pittsburgh, Current: Carnegie Mellon University (*Same group)

Current: Carnegie Mellon University, University of Pittsburgh, Case Western Reserve University, University of Wisconsin, University of Michigan, Mount Sinai University, Neuronoff, Inc., Synchron

Former: Bionics Institute

Former: University of Alberta

Former: University of Calgary