title: Design and validation of a fully implantable, chronic, closed-loop neuromodulation device with concurrent sensing and stimulation.
abstract: Chronically implantable, closed-loop neuromodulation devices with concurrent sensing and stimulation hold promise for better understanding the nervous system and improving therapies for neurological disease. Concurrent sensing and stimulation are needed to maximize usable neural data, minimize time delays for closed-loop actuation, and investigate the instantaneous response to stimulation. Current systems lack concurrent sensing and stimulation primarily because of stimulation interference to neural signals of interest. While careful design of high performance amplifiers has proved useful to reduce disturbances in the system, stimulation continues to contaminate neural sensing due to biological effects like tissue-electrode impedance mismatch and constraints on stimulation parameters needed to deliver therapy. In this work we describe systematic methods to mitigate the effect of stimulation through a combination of sensing hardware, stimulation parameter selection, and classification algorithms that counter residual stimulation disturbances. To validate these methods we implemented and tested a completely implantable system for over one year in a large animal model of epilepsy. The system proved capable of measuring and detecting seizure activity in the hippocampus both during and after stimulation. Furthermore, we demonstrate an embedded algorithm that actuates neural modulation in response to seizure detection during stimulation, validating the capability to detect bioelectrical markers in the presence of therapy and titrate it appropriately. The capability to detect neural states in the presence of stimulation and optimally titrate therapy is a key innovation required for generalizing closed-loop neural systems for multiple disease states.
authors.affiliation: Medtronic Neuromodulation, Minneapolis, MN 55432, USA. scott.stanslaski@medtronic.com
authors.forename: Scott
authors.initials: S
authors.lastname: Stanslaski
authors.forename: Pedram
authors.initials: P
authors.lastname: Afshar
authors.forename: Peng
authors.initials: P
authors.lastname: Cong
authors.forename: Jon
authors.initials: J
authors.lastname: Giftakis
authors.forename: Paul
authors.initials: P
authors.lastname: Stypulkowski
authors.forename: Dave
authors.initials: D
authors.lastname: Carlson
authors.forename: Dave
authors.initials: D
authors.lastname: Linde
authors.forename: Dave
authors.initials: D
authors.lastname: Ullestad
authors.forename: Al-Thaddeus
authors.initials: AT
authors.lastname: Avestruz
authors.forename: Timothy
authors.initials: T
authors.lastname: Denison
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001676:Biofeedback, Psychology / Q000295:instrumentation* / Q000502:physiology; D001921:Brain / Q000502:physiology*; D046690:Deep Brain Stimulation / Q000295:instrumentation*; D004569:Electroencephalography / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D019736:Prostheses and Implants; D012756:Sheep; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation