Neuroprosthetics and Solutions for Spinal Cord Dysfunctions/DoD/Army

Principle Investigator: Doug Weber, Ph.D.

Co-Investigators: Michael Boninger, MD, Rory Cooper, Ph.D.

2008-2010

The overall goal of this proposal is to integrate the neuroprosthetic limb as a natural component of the user’s sensorimotor apparatus.  This will be accomplished in four primary project objectives:

            1. Develop a somatosensory neural interface (SSNI)

            2. Establishment of Neural interface stability and optimization

            3. Utilization of a virtual reality environment for prosthetic training and testing

            4. Prosthetic hardware testing

PROJECT 1:   Develop a somatosensory neural interface (SSNI)

The overall goal of project 1 is to restore natural sensations of limb posture and movement through multichannel microstimulation of the normal afferent pathways involved in proprioception. To achieve this goal, we must first identify an appropriate location to apply microstimulation. In months 1-9 of this project, we will do experiments to evaluate the somatotopic organization of 3 candidate sites. The ideal site is one in which the neurons for each body location and afferent modality are colocated, allowing a single electrode to activate multiple neurons of a similar class (i.e. homonymous afferents). In months 3-12, we will do experiments to quantify the amount of information that can be transmitted to the brain by multichannel afferent microstimulation.

PROJECT 2:  Establishment of Neural interface stability and optimization

The implanted neural interface must remain stable throughout the lifespan of the user, but immune and inflammatory reactions at the implant site are known to degrade the performance of implanted microelectrodes. Since tissue reactions vary in different parts of the nervous system, our first objective is to compare the responses in the DRG, dorsal root nerve, and spinal cord. Our second objective is to test whether surface coating, with agents that encourage specific neuronal survival and growth and reduce inflammation, will be effective in improving the biocompatibility. In months 1-6, we will implant surface-treated and untreated microelectrode arrays. Histological analysis of the implant sites will be performed in months 3-12 to characterize the tissue response around the implant site.

PROJECT 3:  Utilization of a virtual reality (VR) environment for prosthetic training and testing

A virtual environment will be created that will allow amputees to: 1) test simulated neuroprosthetics and control algorithms, and 2) practice using the neuroprosthetic in a virtual training environment. During months 1-6 of FY06, we will acquire and assemble the hardware and software for creating a VR system. In months 3-12, we will develop the VR applications needed for neuroprosthetic training and begin testing of the VR system with upper extremity amputees. The main question that will be addressed is: does placing an upper limb amputee into an environment with a virtual arm increase the EMG signal content of residual limb muscles? If so, VR training will improve the performance of myoelectrically controlled prosthetic arms.     

PROJECT 4:  Prosthetic hardware testing

Little objective or validated information exists about the quality and functional reliability of prostheses. We will develop a system for life-cycle testing of a variety of prosthetic limbs. Data provided by this testing will be used to establish performance and construction standards for prosthetic design and manufacturing. In months 1-6, we will design and construct a testbed for evaluating a range of commercially available prosthetic feet. In months 3-12, we will develop the data acquisition system and complete pilot testing on a small number of prosthetic feet.