Preliminary validation of an implantable bi-directional neural interface for chronic, in vivo investigation of brain networks
ABSTRACT This paper describes the preliminary technology validation of a bi-directional neural interface in an awake large animal model (ovine). The device addresses the major requirements of a chronic research system, including operation within the implantable environment and electrical stimulation with concurrent bioelectric sensing. Preliminary chronic measurements of network dynamics demonstrate that a chronically stable bi-directional interface to the nervous system is achievable. This was shown through chronic impedance and evoked potential measurements in the thalamo-cortical circuit of Papez. Characterization of bioelectric sensing in the presence of stimulation was also performed through measurements of the noise floor in the presence and absence of stimulation. Further technology validation was performed by using the prototype to correlate activity within and between structures in the circuit of Papez in the presence and absence of stimulation.
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ABSTRACT: The current state of neuromodulation can be cast in a classical dynamic control framework such that the nervous system is the classical "plant", the neural stimulator is the controller, tools to collect clinical data are the sensors, and the physician's judgment is the state estimator. This framework characterizes the types of opportunities available to advance neuromodulation. In particular, technology can potentially address two dominant factors limiting the performance of the control system: "observability," the ability to observe the state of the system from output measurements, and "controllability," the ability to drive the system to a desired state using control actuation. Improving sensors and actuation methods are necessary to address these factors. Equally important is improving state estimation by understanding the neural processes underlying diseases. Development of enabling technology to utilize control theory principles facilitates investigations into improving intervention as well as research into the dynamic properties of the nervous system and mechanisms of action of therapies. In this paper, we provide an overview of the control system framework for neuromodulation, its practical challenges, and investigational devices applying this framework for limited applications. To help motivate future efforts, we describe our chronically implantable, low-power neural stimulation system, which integrates sensing, actuation, and state estimation. This research system has been implanted and used in an ovine to address novel research questions.Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2011; 2011:671-4. DOI:10.1109/IEMBS.2011.6090150