Artifact-free and high-temporal-resolution in vivo opto-electrophysiology with microLED optoelectrodes.

Kim, Kanghwan; Vöröslakos, Mihály; Seymour, John P; Wise, Kensall D; Buzsáki, György; Yoon, Euisik · Nat Commun · 2020

basic_science · Level V

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Abstract

The combination of in vivo extracellular recording and genetic-engineering-assisted optical stimulation is a powerful tool for the study of neuronal circuits. Precise analysis of complex neural circuits requires high-density integration of multiple cellular-size light sources and recording electrodes. However, high-density integration inevitably introduces stimulation artifact. We present minimal-stimulation-artifact (miniSTAR) μLED optoelectrodes that enable effective elimination of stimulation artifact. A multi-metal-layer structure with a shielding layer effectively suppresses capacitive coupling of stimulation signals. A heavily boron-doped silicon substrate silences the photovoltaic effect induced from LED illumination. With transient stimulation pulse shaping, we reduced stimulation artifact on miniSTAR μLED optoelectrodes to below 50 μV<sub>pp</sub>, much smaller than a typical spike detection threshold, at optical stimulation of >50 mW mm<sup>-2</sup> irradiance. We demonstrated high-temporal resolution (<1 ms) opto-electrophysiology without any artifact-induced signal quality degradation during in vivo experiments. MiniSTAR μLED optoelectrodes will facilitate functional mapping of local circuits and discoveries in the brain.

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