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. 2013 Apr;10(2):026010.
doi: 10.1088/1741-2560/10/2/026010. Epub 2013 Feb 21.

An implantable wireless neural interface for recording cortical circuit dynamics in moving primates

David A Borton  1 , Ming Yin, Juan Aceros, Arto Nurmikko
Affiliations

An implantable wireless neural interface for recording cortical circuit dynamics in moving primates

David A Borton et al. J Neural Eng. 2013 Apr.

Abstract

Objective: Neural interface technology suitable for clinical translation has the potential to significantly impact the lives of amputees, spinal cord injury victims and those living with severe neuromotor disease. Such systems must be chronically safe, durable and effective.

Approach: We have designed and implemented a neural interface microsystem, housed in a compact, subcutaneous and hermetically sealed titanium enclosure. The implanted device interfaces the brain with a 510k-approved, 100-element silicon-based microelectrode array via a custom hermetic feedthrough design. Full spectrum neural signals were amplified (0.1 Hz to 7.8 kHz, 200× gain) and multiplexed by a custom application specific integrated circuit, digitized and then packaged for transmission. The neural data (24 Mbps) were transmitted by a wireless data link carried on a frequency-shift-key-modulated signal at 3.2 and 3.8 GHz to a receiver 1 m away by design as a point-to-point communication link for human clinical use. The system was powered by an embedded medical grade rechargeable Li-ion battery for 7 h continuous operation between recharge via an inductive transcutaneous wireless power link at 2 MHz.

Main results: Device verification and early validation were performed in both swine and non-human primate freely-moving animal models and showed that the wireless implant was electrically stable, effective in capturing and delivering broadband neural data, and safe for over one year of testing. In addition, we have used the multichannel data from these mobile animal models to demonstrate the ability to decode neural population dynamics associated with motor activity.

Significance: We have developed an implanted wireless broadband neural recording device evaluated in non-human primate and swine. The use of this new implantable neural interface technology can provide insight into how to advance human neuroprostheses beyond the present early clinical trials. Further, such tools enable mobile patient use, have the potential for wider diagnosis of neurological conditions and will advance brain research.

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Figures

Figure 1
Figure 1
Wirelessly recorded data from implanted neural interface in non-human primate. Each line (a) contains 10 seconds of unprocessed, raw data (a, top), offline extracted spike raster data (a, middle), and externally computer running firing rate histogram (a, bottom). Channel 6 is expanded (b) to show examples of neural spikes in the data, and further, (c) shows example extracted waveform.
Figure 2
Figure 2
A wireless neural interface, hermetically sealed, for untethered neuroscience and clinical use. An image of the device after hermetic closure (a) and ready for implant. In a view through the single crystal sapphire window (b), used for electromagnetic transparency, the receiving power coil (red) and the wide band data telemetry chip antenna (blue) can be seen. The intracortical neurosensor, manufactured at Blackrock Microsystems (c), and a reference wire can be seen in relation to the subcutaneous enclosure. Individual wires enter the enclosure through Pt/Ir and ceramic feedthroughs from a flexible polymer (d) interconnect board sealed to the bottom (outside) of the titanium enclosure. The interconnect board is packaged in biocompatible silicone rubber to maintain robust electrical isolation of the input electrodes.
Figure 3
Figure 3
Architecture, assembly, and functions of a hermetically sealed, wireless, battery powered neural interface. Overview of the wireless neural interface as a subcutaneous implant (not to scale), showing the location of the intracortical microelectrode array and supracranial wireless module (a). The device operates in two modes, battery charging and continuous recording, and is separated into two units, cortical (the commercial MEA) and cranial (the hermetically sealed active electronics). Exploded view (b) of the to scale neurosensor device. The Amplification Board integrates a preamplifier application specific integrated circuit (ASIC) chip, two successive approximation analog-to-digital converters (SAR-ADCs), a controller ASIC, and a 24MHz crystal oscillator (online Methods). The Transmission Board contains a receiving coil for power harvesting: a 27-turn 27mm outer diameter coil made from 46-AWG 40-strand Litz wire for minimum loss.
Figure 4
Figure 4
Electronic schematics of neural interface, amplification circuitry, and telemetry unit. (a) Block diagram of the implantable module, including AB and TxB. The TxB (above the dotted line) receives a TTL input from the AB (below the dotted line) that modulates a freely running commercial VCO. (b) The circuit block diagram of the 100-ch CMOS preamplifier ASIC is shown. The preamplifier uses a capacitive-feedback, folded cascode operational transconductance amplifier (OTA) configuration with a source follower output buffer. (c) The RF superheterodyne receiver (Rx) is shown using a polarized antenna to reduce the sensitivity to movement of the transmitter antenna.
Figure 5
Figure 5
Temperature vs. time profile of the neural interface during the charging process. The device was charged at a constant 60mA charging current (+30.2mA for the system itself to run), necessitating about 2W of forward powered from the external charger. Experimental temperature measurements in air on benchtop (green, dotted), modeled air calculations (blue, dashed), and modeled calculations of the system in biological tissue (red, solid) are shown in the figure. We operated the neural interface in the first 1000 seconds shown on this plot and applied active cooling to maintain skin temperature at or near 37°C.
Figure 6
Figure 6
X-Ray images of implanted neural interface, several months following surgery. Four neural interfaces were implanted in a total of two Yorkshire pigs (a) and two rhesus macaque non-human primates (b). A to-scale skull comparison is shown between animals. In swine, the device can be seen embedded between the cancellous bone and outer table of the cranium. In monkey, X-Ray shows device implanted on outer table of cranium.
Figure 7
Figure 7
Wirelessly recorded data from implanted neural interface in non-humanprimates. (a) A selection of 15 of the 100 broadband recording channels richness of high-sample rate (20ksps) data collection. Spikes were extracted (b) on all channels (c) showing single neuron activity on input channels. Raster plot (12s) marking spike timestamps for all input channels is shown with behavior indicated by color overlay. A recording session in primates (e) where subject reaches for food while neural data is recorded wirelessly. Spikes across all channels are reduced to a low-dimensional state space (f) through principal component analysis. We present such neural trajectories produced during free movement of monkey JR: scratching eye (blue), touching an apple (green) and turning head (purple).
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References

    1. Jones Kelly E., Campbell Patrick K., Normann Richard A. A glass/silicon composite intracortical electrode array. Annals of biomedical engineering. 1992 Jul;20(4):423–437. - PubMed
    1. Nordhausen Craig T., Maynard Edwin M., Normann Richard A. Single unit recording capabilities of a 100 microelectrode array. Brain Research. 1996 Jul;726(1-2):129–140. - PubMed
    1. Afshar Pedram, Moran Daniel, Rouse Adam, Wei Xuan, Denison Tim. Validation of chronic implantable neural sensing technology using electrocorticographic (ECoG) based brain machine interfaces; 5th International IEEE/EMBS Conference on Neural Engineering; IEEE; Apr, 2011. pp. 704–707.
    1. Rousche Patrick J, Normann Richard A. Chronic recording capability of the Utah Intracortical Electrode Array in cat sensory cortex. Journal of Neuroscience Methods. 1998 Jul;82(1):1–15. - PubMed
    1. Bansal Arjun, Vargas-Irwin Carlos, Donoghue John. Relationships among low-frequency local field potentials, spiking activity, and 3-D reach and grasp kinematics in primary motor and ventral premotor cortices. Journal of neurophysiology. 2011 Jan;105(4):1603–1619. - PMC - PubMed

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