Neural Engineers Convene in Long Beach for Neural Inferfaces Conference

by James Cavuoto, editor

Nearly 500 neural engineers, clinicians, and researchers attended the 2010 Neural Interfaces Conference in Long Beach, CA in June 2010. The event is the offshoot of the NIH’s Neural Prosthesis Workshop and also incorporates the DBS Consortium meeting.

Terry Hambrecht, the first head of the NIH Neural Prosthesis Program, led the conference off with a keynote presentation on the history of neural prostheses. The bulk of the first day was devoted to deep brain stimulation, and Jaimie Henderson of Stanford University chaired several interactive sessions.

The first session dealt with targeting for Parkinson’s disease. Clement Hamani from the University of Toronto spoke about the pedunculopontine nucleus in the brainstem as a potential DBS target for PD. He reported that incidents of falls and “freezing” both declined with PPN stimulation and sleep and cognition also seemed to improve.

William Marks from UCSF summarized a new study published in the New England Journal of Medicine that reported comparable long-term benefit from both GPi and STN stimulation [NBR Jun10 p5]. Cameron McIntyre from the Cleveland Clinic reviewed some of his computational models of DBS, which graphically and interactively depict the volume of tissue directly activated by DBS. He uses finite element analysis to predict the effect of changing stimulation parameters or lead location.
McIntyre reported that using the model allowed for a 66 percent reduction in electrical power requirements compared to typical clinical settings. “When you’re running blind, you tend to err on the side of more [stimulation] is better,” he explained.

In an afternoon session on closed-loop control of DBS, Martha Morell from Stanford and NeuroPace summarized trials of the NeuroPace RNS device. In addition to the reduction in seizure frequency reported earlier, Morell noted that response rate grows over time from 30 percent to 60 percent.

The second day of the conference was devoted to neural prostheses and neural implants. James Weiland of USC moderated a session on retinal prostheses that was highlighted by the presence of two users of Second Sight’s Argus implant. The users shared their experiences with their devices and fielded questions from attendees.

Mark Humayun from USC and Second Sight gave attendees an update on the Argus II implant, which features 60 electrodes. He showed positive results from users navigating a room who could successfully find a randomly placed door. Shelley Fried from Massachusetts General Hospital spoke about the use of sinusoidal stimulation, as opposed to pulses, in order to improve selectivity in retinal stimulation. He noted that low-frequency stimulation targets presynaptic neurons while high-frequency stimulation targets retinal ganglion cells directly. Daniel Palanker from Stanford spoke on the use of pulsed infrared light and a photovoltaic retinal prosthesis. His lab has constructed a microelectrode array of 512 elements in an area of 1.7 square millimeters.

In a later session, Robert Chow from USC spoke about optogenetic approaches to retinal prostheses using channel Rhodopsin2 and stimulation with light of wavelength 470 nm. Frank Werblin from UC Berkeley went into more detail about optogenetic stimulation, facetiously advising attendees to “throw away all the electrodes and come with me.” His lab targets cell bodies using ChR2 to excite and dendrites using halorhodopsin for inhibition.

In an afternoon session on activity-dependent plasticity, John Marting of Columbia University reported that stimulation of cortico-spinal tract fibers spared after an injury makes them denser, stronger, and more effective in controlling movements. Reggie Edgerton from UCLA spoke about rehabilitation after spinal cord injury using epidural stimulation. He noted that proprioceptive information associated with weight-bearing stepping could serve as a control for functional locomotion. Edelle Field-Fote from the University of Miami spoke of detrimental plasticity that can occur after spinal cord injury.

On the third day of the conference, Ted Berger from USC updated attendees on his work on a microchip-based hippocampus prosthesis. Gregory Worrell from the Mayo Clinic gave a review of recent brain stimulation clinical trials for treatment of epilepsy, including the Medtronic SANTE trial and the Neuro­Pace RNS trial. He also mentioned the first patient in NeuroVista’s epilepsy prediction system recently implanted in Australia.

Exhibitors at the conference included Medtronic, Quallion, Blackrock Microsystems, Plexon, and NeuroNexus.