The aim of the workshop is to determine the current state of neuroengineering with respect to restoration of movement via peripheral nerve simulation, and to discuss future directions. The main themes will include optimizing stimulation through modeling of the nerves, electrode designs for improved recruitment and selectivity, and testing movement control via musculoskeletal modeling.
|8:00-8:45am||Welcome reception with continental breakfast|
|8:45-9:00am||Welcome and introduction: Avner Friedman and Dawn Taylor|
|Modeling of nerve stimulation|
|9:00-9:15am||Cameron McIntyre: Intro and overview of field|
|9:15-10:05am||Jay Rubenstein: The effects of neural modeling on speech processing research for cochlear implants|
|Strategies in applied perifereal nerve stimulation|
|10:30-10:45am||Ron Triolo: Intro and overview of field|
|10:45-11:30am||Ken Yoshida: Strategies in applied peripheral nerve stimulation I|
|11:45-12:30pm||Dick Normann: Strategies in peripheral nerve stimulation|
|12:30-2:15pm||Discussion (working lunch)|
|2:15-2:45pm||Posters and break|
|Biomechanical modeling for restoration of movement|
|2:45-3:00pm||Bob Kirsch: Intro and overview of field|
|3:00-3:50pm||Rahman Davoodi: Biomechanical modeling for restoration of movement|
|5:00-7:00pm||Reception & posters|
Neural prostheses for restoration of limb movement in paralyzed and amputee patients tend to be complex systems. Subjective intuition and trial and error approaches have been applied to the design and clinical fitting of simple systems with limited functionality. These approaches are time consuming, difficult to apply in larger scale, and not applicable to limbs under development with more anthropomorphic motion and actuation. The field of neural prosthetics is in need of more systematic methods, including tools that will allow users to develop accurate models of neural prostheses and simulate their behavior under various conditions before actual manufacturing or clinical application. Such virtual prototyping would provide an efficient and safe test-bed for narrowing the design choices and tuning the control parameters before actual clinical application. In this talk, I will discuss the need for biomechanical modeling of neural prostheses and review existing biomechanical modeling tools and their applications. Then, I will discuss the challenges to accurate modeling and simulation of neural prostheses and its application to design and fit neural prostheses to paralyzed and amputee patients.
Detailed models of extracellular nerve stimulation have been employed for over 30 years to unlock many of the mysteries of electrically activating the human body. Nerve stimulation models consist of two fundamental features: 1) a model of the electric field generated by the stimulating electrode(s), and 2) a model of the neuron(s) being stimulated. Since their inception nerve stimulation models have progressively evolved to more accurately represent the nuances of bioelectric fields, fiber morphology, and axon membrane dynamics. This presentation will provide a brief overview of the field of nerve stimulation modeling and describe how these models have worked to improve the clinical implementation of neurostimulation technology.
Producing stance, sit-to-stance, and gait as well as other forms of skeletal muscular control in parapalegic individuals requires selective activation of specific muscle groups. In order to achieve this muscle activation in a fatigue resistant fashion, the stimulation should be delivered in as physiological a manner as possible. We have been evaluating the potential of the Utah Slanted Electrode Array (USEA) to achieve such physiological, fatigue-resistant activation of extensor muscles in the ankle, knee, and hip of the anesthetized feline.
Problems we have focused on are: improving and automating characterization of the USEA nerve interface; measuring the kinematics of the sit-to-stand maneuver in the cat; achieving surgical access to the nerves innervating the muscles of the hip, knee, and ankle; automated mapping of implanted electrodes to specific muscles; automated evaluation of electrode-muscle stimulation selectivity; stimulation strategies for recruiting graded force in the extensors of the hind limb; and stimulation strategies for producing tremor-free, fatigue resistant forces in these muscles.
Highlights of the progress made in each of these areas will be described in this presentation.
Supported by NIH RO1 NS039677 and HHSN 265200423621C
Attempts to electrically stimulate the cochlea long preceded attempts to model responses of the auditory nerve to electrical stimulation. Indeed the technology to test neural stimulation models in human subjects is a relatively recent phenomenon despite the fact that it has been over 50 years since the first cochlear implant. Neural modeling predicts a number of observations with cochlear implants that are verified, and several that are not. In this lecture i will review those findings that are consistent with such models and those that defy model-based explanation. Some novel stimulation strategies predicted from neural modeling will be reviewed.
The concept of electrical stimulation of muscles and nerves dates back to a time before that of Galvani (1783). Our current approach of Functional Electrical Stimulation (FES) has been significantly refined to a technique that restores function and control to limbs and organs paralyzed as a result of stroke, spinal cord injury, or traumatic injury to the nervous system. With the goal of achieving reliable control over muscle activation, or more generally, reliable control of restored function, the focus becomes selectivity and stability of neural interfaces in the peripheral nerves.
Although advanced stimulation waveforms and feedback control systems can be devised to improve the functional outcome of FES, ultimately the quality and controllability of the FES system is fundamentally limited by the selectivity and stability of the neural prosthesis interface. To address these challenges, we have developed a flexible, thin-film multi-channel, intra-fascicular neural prosthetic interface, the thin-film Longitudinal Intra-Fascicular Electrode (tfLIFE). Our current work ranges from computer simulations of electrode selectivity, through electrode platform design and modifications to animal testing and validation of the technique. The intrafascicular technique will be compared and contrasted with other available peripheral nerve stimulation strategies, such as multi-channel cuff electrodes, intra-muscular electrodes, and inter-fascicular approaches.