A Wideband Dual-Antenna Receiver for Wireless Recording From Animals Behaving in Large Arenas

• Type of Material: Article
• Authors: Seung Bae Lee, Georgia Institute of Technology; Ming Yin, Brown University; Joseph Manns, Emory University; Maysam Ghovanloo, Georgia Institute of Technology
• Language: English
• Date: 2013-07
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 IEEE
• Final Published Version (URL): http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6463438
• Title of Journal or Parent Work: IEEE Transactions on Biomedical Engineering
• ISSN: 0018-9294
• Volume: 60
• Issue: 7
• Start Page: 1993
• End Page: 2004
• Grant/Funding Information: This work was supported in part by the National Institute of Health, NINDS Grant 1R01NS062031-01A1, and the National Science Foundation under Award ECCS-824199.
• Keywords: neural recording; wideband receiver; Behavioral neuroscience; pulse width modulation (PWM); neural prosthesis; in vivo
• Research Categories: Health Sciences, Human Development; Biology, Neuroscience; Engineering, Biomedical

Abstract

A low-noise wideband receiver (Rx) is presented for a multichannel wireless implantable neural recording (WINeR) system that utilizes time-division multiplexing of pulse width modulated (PWM) samples. The WINeR-6 Rx consists of four parts: 1) RF front end; 2) signal conditioning; 3) analog output (AO); and 4) field-programmable gate array (FPGA) back end. The RF front end receives RF-modulated neural signals in the 403–490 MHz band with a wide bandwidth of 18 MHz. The frequency-shift keying (FSK) PWM demodulator in the FPGA is a time-to-digital converter with 304 ps resolution, which converts the analog pulse width information to 16-bit digital samples. Automated frequency tracking has been implemented in the Rx to lock onto the free-running voltage-controlled oscillator in the transmitter (Tx). Two antennas and two parallel RF paths are used to increase the wireless coverage area. BCI-2000 graphical user interface has been adopted and modified to acquire, visualize, and record the recovered neural signals in real time. The AO module picks three demultiplexed channels and converts them into analog signals for direct observation on an oscilloscope. One of these signals is further amplified to generate an audio output, offering users the ability to listen to ongoing neural activity. Bench-top testing of the Rx performance with a 32-channel WINeR-6 Tx showed that the input referred noise of the entire system at a Tx–Rx distance of 1.5 m was 4.58 μVrms with 8-bit resolution at 640 kSps. In an in vivo experiment, location-specific receptive fields of hippocampal place cells were mapped during a behavioral experiment in which a rat completed 40 laps in a large circular track. Results were compared against those acquired from the same animal and the same set of electrodes by a commercial hardwired recording system to validate the wirelessly recorded signals.