Affiliated with Université Laval & CERVO Research Centre

A Wireless Headstage for Combined Optogenetics and Multichannel Electrophysiological Recording.

TitleA Wireless Headstage for Combined Optogenetics and Multichannel Electrophysiological Recording.
Publication TypeJournal Article
Year of Publication2017
AuthorsGagnon-Turcotte G, LeChasseur Y, Bories C, Messaddeq Y, De Koninck Y, Gosselin B
JournalIEEE Trans Biomed Circuits Syst
Volume11
Issue1
Pagination1-14
Date Published2017 Feb
ISSN1940-9990
KeywordsAction Potentials, Animals, Electrophysiological Phenomena, Equipment Design, Mice, Transgenic, Microelectrodes, Optogenetics, Signal-To-Noise Ratio, Wireless Technology
Abstract

<p>This paper presents a wireless headstage with real-time spike detection and data compression for combined optogenetics and multichannel electrophysiological recording. The proposed headstage, which is intended to perform both optical stimulation and electrophysiological recordings simultaneously in freely moving transgenic rodents, is entirely built with commercial off-the-shelf components, and includes 32 recording channels and 32 optical stimulation channels. It can detect, compress and transmit full action potential waveforms over 32 channels in parallel and in real time using an embedded digital signal processor based on a low-power field programmable gate array and a Microblaze microprocessor softcore. Such a processor implements a complete digital spike detector featuring a novel adaptive threshold based on a Sigma-delta control loop, and a wavelet data compression module using a new dynamic coefficient re-quantization technique achieving large compression ratios with higher signal quality. Simultaneous optical stimulation and recording have been performed in-vivo using an optrode featuring 8 microelectrodes and 1 implantable fiber coupled to a 465-nm LED, in the somatosensory cortex and the Hippocampus of a transgenic mouse expressing ChannelRhodospin (Thy1::ChR2-YFP line 4) under anesthetized conditions. Experimental results show that the proposed headstage can trigger neuron activity while collecting, detecting and compressing single cell microvolt amplitude activity from multiple channels in parallel while achieving overall compression ratios above 500. This is the first reported high-channel count wireless optogenetic device providing simultaneous optical stimulation and recording. Measured characteristics show that the proposed headstage can achieve up to 100% of true positive detection rate for signal-to-noise ratio (SNR) down to 15 dB, while achieving up to 97.28% at SNR as low as 5 dB. The implemented prototype features a lifespan of up to 105 minutes, and uses a lightweight (2.8 g) and compact [Formula: see text] rigid-flex printed circuit board.</p>

DOI10.1109/TBCAS.2016.2547864
Alternate JournalIEEE Trans Biomed Circuits Syst
PubMed ID27337721