Engineers Penetrate the Nervous System at NIH Neural Prosthesis Workshop
by James Cavuoto, editor
The 32nd NIH Neural Prosthesis Workshop, held in Bethesda, MD, Oct. 17-19, lived up to its legacy as the annual gathering of researchers funded by the NIH Neural Prosthesis Program and other NIH Institutes. Over 200 biomedical engineers, neuroscientists, clinicians, and device manufacturers attended this year’s event, despite heightened security at the federal agency.

The workshop kicked off with a panel discussion featuring current users of neural prostheses, including recipients of a cochlear implant, deep-brain stimulation system for treatment of Parkinsons’ disease, the Freehand hand grasp stimulator, and an experimental standing prosthesis for paraplegics developed at the Cleveland Functional Electrical Stimulation Center. The users offered feedback on their devices and suggestions for improvements in next-generation products. High on several users’ wish list is smaller components and power supplies, and simpler surgeries for implanting their devices. But mostly, the users expressed extreme satisfaction with their neural prostheses, and each said they would not want to do without them.

A panel of neural prosthesis users offered feedback on their devices during the workshop.

There was general agreement that despite the tremendous success of the different devices, there is still a lack of awareness and appreciation for the prostheses within patient communities. In part this is because many clinicians are either unaware of the progress that has been made or reluctant to recommend neural prostheses because of reimbursement or other financial issues. A bigger factor, however, is the attitude among many patients and clinicians that a cure for their particular disease or disorder is imminent and that neural prostheses represent a form of rehabilitation, and not a cure.

One of the trends in this year’s workshop was a significant amount of work in implanting electrodes in the brain and spinal cord. Several presenters described electrode arrays implanted in the cerebral cortex for potential neural control or neural prosthetic applications [see sidebar]. Several other researchers, including teams from the University of Alberta, Massachusetts Institute of Technology, Case Western Reserve University, and Huntington Medical Research Institutes, discussed direct stimulation of the spinal cord as a potential method of eliciting “motor primitives” for walking and other activities, an approach that may prove to be much simpler than current strategies of patterned stimulation of multiple lower limb muscles.

Advances in technology were also preeminent at the workshop. Richard Normann from the University of Utah described the advantages of the Utah Slanted Electrode Array, which he said offers greater selectivity of fibers within a nerve fascicle since different electrodes in the array reach different depths within the nerve. In a comprehensive overview presentation, David Martin from the University of Michigan highlighted several recent advances in biomaterials used in brain electrodes. Martin argued for rough, as opposed to smooth, electrode surfaces in order to improve biocompatibility, electrical responsiveness, cellular interactions, and mechanical stress characteristics. The Michigan group has worked with a number of promising new bioactive conducting polymers such as polypyrole and a Bristol-Myers compound called PEDOT that enrich the neural-electrode interface.

Hunter Peckham from the Cleveland FES Center proposed a “networked neuroprosthetic system” that would consist of multiple small implantable modules that communicate with each other via an open architecture hub-based network. Each hub would supply self-contained power to multiple stimulators and/or sensors, each with multiple channels. The communication medium would be wireless or possibly the body tissue itself. Not to be outdone, Joe Schulman from the Alfred Mann Foundation proposed a network of battery-powered BIONs that communicate using a star topology.

Gerald Loeb from the University of Southern California/Alfred Mann Institute reported results from clinical trials of BIONs used for therapeutic stimulation. In stroke patients, stimulation for an hour a day, shoulder subluxation was reduced and preliminary results from patients with knee osteoarthritis look similarly promising. Another BION team reported results from urinary incontinence trials. BION stimulation for 8 to 14 hours per day produced an increase in maximum bladder volume and a decrease in daily and nocturnal voids.

More than three dozen poster presentations complemented the oral presentations, in six areas: auditory prostheses, biomaterials, brain-computer interfaces, functional electrical stimulation, and responses to neural prosthesis insertion.

Click here for editors' pick of top three presentations.

Click here for a list of companies at the workshop.