Neuroengineering tools/applications for bidirectional interfaces, brain-computer interfaces, and neuroprosthetic implants - a review of recent progress

Abstract

The main focus of this review is to provide a holistic amalgamated overview of the most recent human in vivo techniques for implementing brain-computer interfaces (BCIs), bidirectional interfaces, and neuroprosthetics. Neuroengineering is providing new methods for tackling current difficulties; however neuroprosthetics have been studied for decades. Recent progresses are permitting the design of better systems with higher accuracies, repeatability, and system robustness. Bidirectional interfaces integrate recording and the relaying of information from and to the brain for the development of BCIs. The concepts of non-invasive and invasive recording of brain activity are introduced. This includes classical and innovative techniques like electroencephalography and near-infrared spectroscopy. Then the problem of gliosis and solutions for (semi-) permanent implant biocompatibility such as innovative implant coatings, materials, and shapes are discussed. Implant power and the transmission of their data through implanted pulse generators and wireless telemetry are taken into account. How sensation can be relayed back to the brain to increase integration of the neuroengineered systems with the body by methods such as micro-stimulation and transcranial magnetic stimulation are then addressed. The neuroprosthetic section discusses some of the various types and how they operate. Visual prosthetics are discussed and the three types, dependant on implant location, are examined. Auditory prosthetics, being cochlear or cortical, are then addressed. Replacement hand and limb prosthetics are then considered. These are followed by sections concentrating on the control of wheelchairs, computers and robotics directly from brain activity as recorded by non-invasive and invasive techniques.

Keywords: bidirectional interface; biocompatibility; bioelectronics; brain–computer interface; brain–machine interface; multielectrode array; neuroengineering; neuroprosthetics.

Figure 1

Schematic description for a BMI that relies on the real-time sampling and processing of large-scale brain activity to control a robotic prosthetic arm. Multiple, chronically implanted, intracranial microelectrode arrays are used to sample the activity of large populations of single cortical neurons simultaneously. The combined activity of these neural ensembles is then transformed by a mathematical algorithm into continuous three-dimensional arm-trajectory signals that can be used to control the movements of a robotic prosthetic arm. A closed control loop is then established by providing the subject with both visual and tactile feedback signals generated by movement of the robotic arm. Reprinted with permission from Macmillan Publishers Ltd: Nature 409, 403–407 (Nicolelis, 2001), copyright 2001.

Figure 2

Example images of MEAs. (A) Cyberkinetics silicon-based 100-channel MEA. (B) View of recordings sites on the Cyberkinetics array. (C) NeuroNexus silicon-based MEA shanks. (D) Tucker-Davis Technologies (TDT) microwire MEA. (E) View of recording sites on the TDT microwire array. (F) Moxon thin-film ceramic-based MEA. (G) View of bond pads on a 36-channel Cyberkinetics array. Reprinted with permission from Elsevier: Brain research 1282, 183–200 (Ward et al., 2009), copyright 2009.

Figure 3

The BrainGate neural interface system created by Cyberkinetics Neurotechnology Systems Incorporated. (A) The BrainGate sensor resting on an American penny, 13 cm ribbon cable and percutaneous titanium pedestal which is attached to the skull. (B) Scanning electron micrograph of the 100 electrode Utah array. (C) Spin-lattice relaxation time (T₁) weighted magnetic resonance image (MRI) of a tetraplegic subject showing the approximate site of sensor implantation. (D) The first participant of the BrainGate system directing a computer cursor toward the orange square on the PC monitor solely by neural signals. Reprinted with permission from Macmillan Publishers Ltd: Nature 442, 164–171 (Hochberg et al., 2006), copyright 2006.