title: Optogenetic activation of neocortical neurons in vivo with a sapphire-based micro-scale LED probe.
abstract: Optogenetics has proven to be a revolutionary technology in neuroscience and has advanced continuously over the past decade. However, optical stimulation technologies for in vivo need to be developed to match the advances in genetics and biochemistry that have driven this field. In particular, conventional approaches for in vivo optical illumination have a limitation on the achievable spatio-temporal resolution. Here we utilize a sapphire-based microscale gallium nitride light-emitting diode (μLED) probe to activate neocortical neurons in vivo. The probes were designed to contain independently controllable multiple μLEDs, emitting at 450 nm wavelength with an irradiance of up to 2 W/mm(2). Monte-Carlo stimulations predicted that optical stimulation using a μLED can modulate neural activity within a localized region. To validate this prediction, we tested this probe in the mouse neocortex that expressed channelrhodopsin-2 (ChR2) and compared the results with optical stimulation through a fiber at the cortical surface. We confirmed that both approaches reliably induced action potentials in cortical neurons and that the μLED probe evoked strong responses in deep neurons. Due to the possibility to integrate many optical stimulation sites onto a single shank, the μLED probe is thus a promising approach to control neurons locally in vivo.
authors.affiliation: Institute of Photonics, Department of Physics, University of Strathclyde Glasgow, UK.
authors.forename: Niall
authors.initials: N
authors.lastname: McAlinden
authors.affiliation: Institute of Photonics, Department of Physics, University of Strathclyde Glasgow, UK.
authors.forename: Erdan
authors.initials: E
authors.lastname: Gu
authors.affiliation: Institute of Photonics, Department of Physics, University of Strathclyde Glasgow, UK.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Dawson
authors.affiliation: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde Glasgow, UK ; Centre for Neuroscience, University of Strathclyde Glasgow, UK.
authors.forename: Shuzo
authors.initials: S
authors.lastname: Sakata
authors.affiliation: Institute of Photonics, Department of Physics, University of Strathclyde Glasgow, UK.
authors.forename: Keith
authors.initials: K
authors.lastname: Mathieson
mesh_terms: D000200:Action Potentials; D000537:Aluminum Oxide / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D000075402:Channelrhodopsins; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D008027:Light; D051379:Mice; D008822:Mice, Transgenic; D009010:Monte Carlo Method; D019579:Neocortex / Q000166:cytology*; D009474:Neurons / Q000502:physiology*; D062308:Optogenetics; D010775:Photic Stimulation; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000099260:Empty Spiracles Homeobox Proteins
chemical_list: D000537:Aluminum Oxide; D000596:Amino Acids; D000075402:Channelrhodopsins; D018398:Homeodomain Proteins; D014157:Transcription Factors; D000099260:Empty Spiracles Homeobox Proteins; C098463:dolaisoleucine
keywords: cortical layers; neural circuit; neurotechnology; optogenetics; μLEDs