Design of a Closed-loop-ready High-channel-count Implant-scale System for Neural Sensing and Stimulation

Speaker: Vahagn Hokhikyan
Affiliation: Ph.D. Candidate - UCLA

Abstract:  According to a report by World Health Organization, neuropsychiatric disorders affect about one billion people worldwide. It’s estimated that about 50 million of those affected suffer from epilepsy, and 24.3 million suffer from Alzheimer disease and other dementias. To address this global epidemic, neuroscientific initiatives are being developed worldwide.

Many neurological disorders do not have cures but are rather chronically managed by different treatment modalities during the patients’ lifespan. Neuromodulation – a process of regulating neuronal populations through electrical stimuli is one of these treatment modalities. Neural implants have come a long way since their introduction in 1960’s and are currently FDA approved to treat Parkinson’s disease, essential tremor, and dystonia. However, the hardware delivering DBS hasn’t changed substantially during these years. Standard DBS probes (Medtronic DBS 3387/3389) have four (4) large ring-shape stimulation sites which result in pea-size or larger activation volumes. In most cases, only one of these sites is being utilized delivering fixed rectangular constant voltage or constant current stimulation pulses in an open-loop fashion ignoring disease state, medication status, or side effects. While the open-loop stimulation paradigm improves patients’ quality of life in most cases, it may cause side effects. Hallucinations, manic responses, low mood, anger, and even suicidal thoughts are some of the side effects of DBS. Thus, sending continuous electrical impulses without any mechanism to detect the effectiveness of therapy may be detrimental to patient’s mental and physical well-being. The two main reasons why stimulation is not applied automatically based on the disease state are 1) the lack of sensing capability in IPGs, and 2) the knowledge gap about the disease biomarkers.

Recent studies conducted to test the effectiveness of higher density probes (eight sites vs four) show that the increase in spatial resolution can improve the therapeutic index and potentially result in less power consumption to achieve the same therapeutic benefits. The status quo of the traditional rectangular stimulation waveforms is also being challenged – some non-rectangular waveforms seem to be more energy efficient. Taking all these recent developments into account in this work we present a more advanced neural implant which, while being backward compatible with traditional DBS therapy, is capable of simultaneously sensing during stimulation, has high-channel-count (64), and can deliver arbitrary stimulation waveforms.

Biography:  Vahagn Hokhikyan received the B.S. degree in computer engineering and the M.S. degree in electrical engineering in 2008 and 2010 respectively from the California State University of Northridge. He is currently working toward the Ph.D. degree in biomedical engineering in University of California, Los Angeles, where he is directing his efforts on further miniaturization and optimization of implantable medical devices. Prior to joining UCLA, he worked in Microsys, Inc. as an embedded hardware and software engineer for four years.  Vahagn Hokhikyan is a licensed professional electrical engineer (PE) in the state of California since December 2011.

For more information, contact Prof. Dejan Markovic ()  

Date(s) - Apr 14, 2017
9:00 am - 12:00 pm

E-IV Tesla Room #53-125
420 Westwood Plaza - 5th Flr., Los Angeles CA 90095