March 2019 issue
March 31, 2019 | Neural engineering professionals from across the globe attended the 9th International IEEE/EMBS Conference on Neural Engineering, held in San Francisco, CA earlier this month. Several neurotech luminaries delivered keynote addresses and featured lectures during the event.
Robert Knight, professor of psychology and neuroscience director emeritus at Helen Wills Neuroscience Institute at UC Berkeley, delivered the opening keynote on March 20. “Neural engineering is going to supplant pharmaceuticals,” he predicted. Knight, a pioneer in interpreting brain signals, stressed the importance of the high-frequency band of about 65 to 250 Hz. “It’s the most salient rhythm in the brain,” he said.
During his talk, Knight challenged several commonly held notions in neuroscience. Urging attendees to “get away from phrenology,” he stressed the significance of communication networks, as opposed to anatomical structures in the brain. He also presented evidence that Broca’s area—once thought to be the locus of articulation—is not actually active during speaking. But neurons there are involved in articulatory planning, which he suggested might be a useful tool for BMI researchers.
Knight mentioned several other significant brain signals, including phase-amplitude coupling between hippocampal theta rhythms and high-frequency bands that has significance during semantic language processing. He also mentioned that theta burst activity from the amygdala drives hippocampal activity during emotional regulation and highlighted a possible biomarker for choice and regret within the orbitofrontal cortex. Looking at memory encoding, Knight highlighted the coupling of signals during slow-wave sleep. Tighter spindles are better, he said, and uncoupling of slow waves from spindles seems to impair memory. He concluded with a discussion of speech prosthesis development. “The more you know about the functioning of the cortex, the better your prosthesis will be,” he said.
In another keynote, Mark George from the Medical University of South Carolina shared his insights from experience getting FDA approval for new neuromodulation therapies, including TMS for treatment-resistant depression. “The brain is an electrochemical organ,” he said. When we remember that we can do amazing things beyond what pharmaceuticals can do.”
George highlighted several keys to successful translation of a new neuromodulation therapy, including knowing the target, knowing whom to enroll in a clinical trial, understanding the placebo effect, and knowing the dosage and the timing of stimulation. He explained the importance of knowing what motor threshold was and advised using 120 percent of that for magnetic stimulation. George also pointed out the value of short theta bursts—50 Hz triplets modulated at 5 Hz—which induce long-term potentiation. This pattern of stimulation can reduce therapeutic TMS sessions from 30 minutes to 5 minutes without any loss of effectiveness. He concluded his talk with a discussion of low-intensity focused ultrasound, which he said could make TMS look “stale and old.”
In a session devoted to neuroprosthetics and neurorehabilitation, Reggie Edgerton from UCLA described his team’s efforts to restore function after SCI using noninvasive spinal stimulation. “Our present dogma about paralysis needs to be thrown out the window,” he said. “There is some fundamental aspect of how we control movement that we have been completely missing.” Drawing a distinction between epidural stimulation and FES, he said the goal was to enable movement, not induce movement. Edgerton’s team uses 10 kHz biphasic stimulation below the spinal cord lesion.
“Our approach has always been broad,” he said. “Spinal cord injury affects all the physiological systems in the body.” He stressed the importance of proprioception and cutaneous sensory information in restoring function.
Other presenters in that session included Richard Weir from the University of Colorado Denver, who presented his work using myoelectric and optogenetic control systems for an upper-extremity motor prosthesis, and Richard O’Donnell from UCSF, who discussed bone-anchored implants in trans-femoral amputees.
In a pre-conference session devoted to entrepreneurship and innovation in neurotechnology, representatives of several commercial firms shared their experiences. Marty Morrell from NeuroPace described her company’s tribulations in the years leading up to FDA approval of their RNS device for epilepsy. “I was the only one in the company who stayed sober,” she said of the day approval finally came.
Morrell stressed the role of data collection in identifying brain biomarkers that are relevant for closed-loop neuromodulation. With more than 4 million ECoG’s NeuroPace has partnered with Google’s cloud platform for storage and analysis. Hinting at future directions for the company, Morrell said NeuroPace has a “huge interest” in episodic diseases, such as depression, addiction, and tic disorders.
Riki Banerjee from Medtronic stressed four key technologies important in her company’s devices: communication, rechargeability, comfort, and MRI compatibility. She described some of the computational models the company uses to factor in variables like posture, coil position, and power.
Daryl Kipke from NeuroNexus Technologies described his company’s new direction after being spun off from Nuvectra earlier this year. “We’re going back to our roots,” he said. “We have the energy of a startup but the capabilities of a long-standing company.” NeuroNexus has 1100 active customers, he said, for probes ranging from thin-film technologies to polymers to optrodes with optical fibers attached to each shank.
Emilio Sacristan from a Cleveland-based startup called Nervive Inc. described his firm’s magnetic stimulation therapy for treating stroke. The device uses bilateral stimulation of the facial nerve to promote vasodilation after CVA.
Asgeir Alexandersson from Ossur in Iceland described some of the current limitations of neuroprosthetic devices. Surface EMG sensors are prone to movement artifacts and sweating. Ossur has been investigating the implanted IMES device as an alternative to EMG.
