R.J. Vetter

University of Michigan, Ann Arbor, MI, United States

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Publications (12)11.17 Total impact

  • Chemical Senses 01/2006; 31(5):A14-A14. · 3.22 Impact Factor
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    ABSTRACT: Cortical recording devices hold promise for providing augmented control of neuroprostheses and brain-computer interfaces in patients with severe loss of motor function due to injury or disease. This paper reports on the preliminary in vitro and in vivo results of our microscale implantable neural interface (MINI) probe system. The MINI is designed to use proven components and materials with a modular structure to facilitate ongoing improvements as new technologies become available. This device takes advantage of existing, well-characterized Michigan probe technologies and combines them to form a multichannel, multiprobe cortical assembly. To date, rat, rabbit, and non-human primate models have been implanted to test surgical techniques and in vivo functionality of the MINI. Results demonstrate the ability to form a contained hydrostatic environment surrounding the implanted probes for extended periods and the ability of this device to record electrophysiological signals with high SNRs. This is the first step in the realization of a cortically-controlled neuroprosthesis designed for human applications.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2005; 7:7341-4.
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    ABSTRACT: Delivering drugs directly to the brain tissue opens new approaches to disease treatment and improving neural interfaces. Several approaches using neural prostheses have been made to deliver drugs directly with bypassing the blood-brain barrier (BBB) [1, 2]. In this paper, we propose a new polymer-based flexible microelectrode with drug delivery capability. The probe was fabricated and tested for electrical and fluidic functionality in early stage design. In vivo chronic recording experiments succeeded in demonstrating the in vivo reliability of the probe. Successful in vivo experiments confirm the suitability of the probes as implantable chronic recording devices with robust fluid delivery function.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2005; 5:5272-5.
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    ABSTRACT: An important aspect of the development of cortical prostheses is the enhancement of suitable implantable microelectrode arrays for chronic neural recording. The objective of this study was to investigate the recording performance of silicon-substrate micromachined probes in terms of reliability and signal quality. These probes were found to consistently and reliably provide high-quality spike recordings over extended periods of time lasting up to 127 days. In a consecutive series of ten rodents involving 14 implanted probes, 13/14 (93%) of the devices remained functional throughout the assessment period. More than 90% of the probe sites consistently recorded spike activity with signal-to-noise ratios sufficient for amplitudes and waveform-based discrimination. Histological analysis of the tissue surrounding the probes generally indicated the development of a stable interface sufficient for sustained electrical contact. The results of this study demonstrate that these planar silicon probes are suitable for long-term recording in the cerebral cortex and provide an effective platform technology foundation for microscale intracortical neural interfaces for use in humans.
    IEEE Transactions on Biomedical Engineering 07/2004; 51(6):896-904. · 2.35 Impact Factor
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    ABSTRACT: Advances in BioMBMS have provided researchers with the capabilities to look at a myriad of things with more detail and precision than ever before, and the brain is no exception to this. The brain is becoming more accessible and controllable on almost every level; the challenge lies in increasing the quality of the interface with the brain. To address this challenge, we must begin by optimizing to the best of our capabilities the implantable devices used. One method to help optimize these devices is to integrate active electronics on the microelectrode that will enhance the quality of the signals being extracted from brain. This paper describes a chronic silicon-substrate microelectrode with integrated analog-front end electronics capable of recording from nearby neurons in active and passive modes of operation. Six-channel 2-D arrays have been chronically implanted into barrel cortex of two rats and have recorded chronic unit activity with SNRs up to 8:1.
    Engineering in Medicine and Biology Society, 2003. Proceedings of the 25th Annual International Conference of the IEEE; 10/2003
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    ABSTRACT: This study investigated the use of planar, silicon-substrate microelectrodes for chronic unit recording in the cerebral cortex. The 16-channel microelectrodes consisted of four penetrating shanks with four recording sites on each shank. The chronic electrode assembly included an integrated silicon ribbon cable and percutaneous connector. In a consecutive series of six rats, 5/6 (83%) of the implanted microelectrodes recorded neuronal spike activity for more than six weeks, with four of the implants (66%) remaining functional for more than 28 weeks. In each animal, more than 80% of the electrode sites recorded spike activity over sequential recording sessions during the postoperative time period. These results provide a performance baseline to support further electrode system development for intracortical neural implant systems for medical applications.
    IEEE Transactions on Neural Systems and Rehabilitation Engineering 07/2003; 11(2):151-5. · 3.26 Impact Factor
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    ABSTRACT: A chief concern in the pursuit of controlling a neuroprosthetic device using direct brain signals is the question of how many bits of information are achievable through a direct brain-machine interface (BMI) via implantable microelectrode devices. This experiment begins to address this issue with implementation of a simple, software based decoding algorithm that allows the brain to adapt to the rules imposed upon it, To test this algorithm, two chronic 16-channel Michigan silicon microelectrode arrays were implanted into the primary motor cortex of two rats to record simultaneous unit spike activity. The animals were trained to perform an auditory detection task by modulating the recorded cortical spike activity in a prescribed manner. Both non-adaptive and adaptive neural decoding algorithms were evaluated. With the implementation of a non-adaptive decoding algorithm, the rats' behavioral (cortical) responses plateaued at approximately 75% correct; however, with the implementation of an adaptive algorithm, the rats' behavioral responses relatively quickly increased to 91% correct. The neural recordings suggest that the brain is able to modulate detailed cortical responses in accordance with the prescribed operant conditioning rules.
    Neural Engineering, 2003. Conference Proceedings. First International IEEE EMBS Conference on; 04/2003
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    ABSTRACT: Surgical techniques are a critical contributor to the level of success achieved with chronically implanted cortical neuroprosthetic devices. Many different factors contribute to the amount of irritation the tissue is exposed to from the implanted device. Factors include mechanical irritations, infectious pathogens, dural regrowth, etc. In this paper we describe a novel application of the hydrogel polymer, ALGELĀ® (Neural Intervention Technologies, Ann Arbor, MI), in conjunction with an implanted Michigan probe (CNCT, University of Michigan). This polymer contains many inherent properties that are beneficial to this type of procedure. Properties include: 1) ease of application, 2) biocompatibility, 3) exemplary mechanical properties, and 4) translucent clarity. We believe that ALGEL has been a large contributor to the high level of success achieved with our chronic electrode implantations.
    Neural Engineering, 2003. Conference Proceedings. First International IEEE EMBS Conference on; 04/2003
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    ABSTRACT: Construction of a direct brain-machine interface (BMI) for neuroprosthetic purposes is at the forefront of many current neural engineering thrusts. Due to recent breakthroughs in device technology and implantation techniques, a basic framework is now sufficiently developed to allow design of systems level interface strategies producing robust, scalable BMIs that adapt quickly to optimize information transfer at the interface. It has been postulated that knowledge of the underlying neural coding is mandatory for further BMI development. In this preliminary report we use an adaptive algorithm requiring limited knowledge of the underlying neural coding to allow naive rats implanted with Michigan silicon microelectrode arrays in motor cortex to perform a tone discrimination task via differential modulation of the recorded signals. One subject was able to perform the task consistently above chance, despite minor daily fluctuations in recording populations and signal quality. The brain rapidly changed response strategies to facilitate performance of the task, and the algorithm subsequently adapted to accommodate improved BMI operation.
    Neural Engineering, 2003. Conference Proceedings. First International IEEE EMBS Conference on; 04/2003
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    ABSTRACT: The desire to perform chronic recordings from many channels in cortex is high among both neuroscientists and neural prosthesis researchers. The Michigan probe with integrated silicon ribbon cable has been used successfully for obtaining chronic cortical recordings in rodents. As these silicon devices are applied in larger animals and potentially in humans, however, a more mechanically robust, scalable system is required. Here we present a device that takes advantage of several existing, well-characterized technologies and methods and combines them to form a hybrid cortical assembly. The components of the assembly include thin-film multichannel silicon probes and polyimide cables that are electrically and mechanically coupled using thermocompression ball bonding. The resulting probe/cable assembly is low profile (<500 microns) and can be combined with other assemblies to form a 3-D array. Sixteen channel 2-D arrays have been implanted into rat motor cortex and have recorded chronic unit activity.
    Neural Engineering, 2003. Conference Proceedings. First International IEEE EMBS Conference on; 04/2003
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    D.R. Kipke, D.S. Pellinen, R.J. Vetter
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    ABSTRACT: BioMEMS devices can be designed to provide viable neural interfaces for long-term, high-density, two-way communication with selected areas of cerebral cortex. Prototype thin-film polymer implantable microelectrode arrays were developed to extend the microelectrode design space in several ways, including enhanced flexibility, engineered surfaces and coatings, and new types of microchannels. Prototype MEMS silicon microdevices were developed as microsurgical tools for reliably inserting the flexible polymer electrodes into the cerebral cortex. Hybrid polymer microdevices were also developed for neural recording and stimulation combined with micro-drug delivery.
    Circuits and Systems, 2002. ISCAS 2002. IEEE International Symposium on; 02/2002
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    ABSTRACT: The promise of advanced neuroprosthetic systems to significantly improve the quality of life for a segment of the deaf, blind, or paralyzed population hinges on the development of an efficacious, and safe, multichannel neural interface for the central nervous system. The candidate implantable device that is to provide such an interface must exceed a host of exacting design parameters. The authors present a thin-film, polyimide-based, multichannel intracortical Bio-MEMS interface manufactured with standard planar photo-lithographic CMOS-compatible techniques on 4-in silicon wafers. The use of polyimide provides a mechanically flexible substrate which can be manipulated into unique three-dimensional designs. Polyimide also provides an ideal surface for the selective attachment of various important bioactive species onto the device in order to encourage favorable long-term reactions at the tissue-electrode interface. Structures have an integrated polyimide cable providing efficient contact points for a high-density connector. This report details in vivo and in vitro device characterization of the biological, electrical and mechanical properties of these arrays. Results suggest that these arrays could be a candidate device for long-term neural implants.
    IEEE Transactions on Biomedical Engineering 04/2001; · 2.35 Impact Factor