May 2016 issue
May 31, 2016 | About 250 neural engineers, clinicians, and neuromodulation industry professionals attended the Neuromodulation: The Science conference in San Francisco, CA earlier this month. The meeting was put on by Neurovations and Elliot Krames, the former president of the International Neuromodulation Society. The conference was a follow-on to the Mechanisms of Action Conference, which took place in Orlando, FL in 2014 [NBR Mar14 p7].
The conference began with an overview of the National Institute of Health’s Stimulating Peripheral Activity to Relieve Conditions (SPARC) program, by program manager Gene Civillico. He described the program as a common fund program reporting directly to the NIH director and with a life of less than 10 years. Civillico said the program seeks to produce go-to resources for developers of new strategies in therapeutic nerve modulation. But he stressed that he wasn’t interested in turning the NIH into DARPA.
Joe Pancrazio from the University of Texas, Dallas, spoke about new polymeric materials used in neural interfaces. The goals are to create less stiff microelectrode arrays and to lower the impedance at the neural interface. Pancrazio’s lab has investigated the conductive polymer PEDOT deposited with counter-ions tetrafluoroborate or polystyrenensulfonate. PEDOT:TFB coated electrodes exhibit a slower decline than PEDOT:PSS coated electrodes, he said.
Dominique Durand from Case Western Reserve University described a novel technique of grafting nanowires into a peripheral nerve. He said it produced a flexible and biocompatible interface. Durand created a carbon nanotube “yarn” made up of many nanotubes. The larger surface area produced impedance an order of magnitude less than platinum electrodes, he said.
Warren Grill from Duke University discussed the attributes of particular stimulation waveforms and described a novel use of computational evolution techniques to find the most beneficial waveforms. He also discussed electrode-neuronal topography, comparing selectivity in parallel vs. perpendicular configurations. He noted that there is a significant difference in stimulating axons of passage as opposed to axons terminating in a nucleus.
Daryl Kipke from NeuroNexus described his firm’s new Buz256 array, an 8 x 32 neural probe intended for high-fidelity neural interfacing. NeuroNexus uses steerable thin film electrode materials.
Dustin Tyler from CWRU described his recent work in sensory neuroprosthetics. His team doubled the number of contacts to 16 in an effort to gain a finer understanding of how touch is coded in the nervous system. His interface produced 19 localizable points of sensation in subjects. Tyler found that increasing the stimulation frequency produced more intense sensations, while increasing the amplitude increased the population of activated sensors.
In a session devoted to functional electrical stimulation, Hunter Peckham, Robert Kirsch, and Kevin Kilgore from CWRU described recent progress in upper extremity neuroprosthetics. Kirsch showed video from two C4 quadriplegics who regained arm and hand function, as well as trunk control. One of the subjects made use of a device combining FES with a robotic exoskeleton.
Another session at the conference examined the science of brain stimulation, looking at potential mechanisms of action for neuromodulation therapies. Cameron McIntyre from CWRU described his recent efforts at constructing a human connectome map. He has worked with Helen Mayberg from Emory University to compare electrode location in responders vs. non-responders to DBS for treatment-resistant depression. McIntyre built a finite element analysis model of activated pathways using DTI tractography techniques. Nonresponders turned into responders when they were reprogrammed using this information, he said.
Andres Lozano from the University of Toronto described his work on DBS of the fornix for treatment of Alzheimer’s disease. He said that the hippocampus can grow after DBS therapy. Lozano said he is considering a new study restricted to patients over the age of 65, who seemed to perform better in the recent ADVANCE clinical trial, which failed a futility analysis last year.
Brain Kopell from Mount Sinai Health described a thalamocortical loop that appears to be a basic building block in all behaviors. He said that the field of cortical stimulation needs more field modeling tools like the DTI tractography techniques used for DBS. He also argued for the development of new stimulation devices spcifically for cortical stimulation. “No more SCS hand me downs,” he pleaded.
Stephen Carcieri from Boston Scientific described his firms’ directional leads for DBS. Directional leads with current steering enable a better therapeutic window, he said, though he stressed that current steering is not a substitute for accurate lead placement.
Exhibitors at the meeting included Nuvectra, Ripple, FemPulse, Nevro, and the Cleveland FES Center.
