Multimodal fast optical interrogation of neural circuitry

Abstract

Our understanding of the cellular implementation of systems-level neural processes like action, thought and emotion has been limited by the availability of tools to interrogate specific classes of neural cells within intact, living brain tissue. Here we identify and develop an archaeal light-driven chloride pump (NpHR) from Natronomonas pharaonis for temporally precise optical inhibition of neural activity. NpHR allows either knockout of single action potentials, or sustained blockade of spiking. NpHR is compatible with ChR2, the previous optical excitation technology we have described, in that the two opposing probes operate at similar light powers but with well-separated action spectra. NpHR, like ChR2, functions in mammals without exogenous cofactors, and the two probes can be integrated with calcium imaging in mammalian brain tissue for bidirectional optical modulation and readout of neural activity. Likewise, NpHR and ChR2 can be targeted together to Caenorhabditis elegans muscle and cholinergic motor neurons to control locomotion bidirectionally. NpHR and ChR2 form a complete system for multimodal, high-speed, genetically targeted, all-optical interrogation of living neural circuits.

Optogenetic therapy for retinitis pigmentosa

“…[26][27][28] Here, we will discuss two microbial molecules: channelrhodopsin-2 from Chlamydomonas reinhardtii (ChR2), a light-gated cation channel that depolarizes ChR2-expressing cells upon light activation, 35,36 and halorhodopsin from the archea Natronomonas pharaonis (NpHR) a light-activated chloride pump that hyperpolarizes NpHR-expressing cells, when these are illuminated. [37][38][39] Light stimulation of healthy retina leads to two different responses in retinal cells. Photoreceptors are hyperpolarized when light intensity increases.…”

Ultra light-sensitive and fast neuronal activation with the Ca2+-permeable channelrhodopsin CatCh

“…The light-gated, inwardly rectifying cation channel channelrhodopsin-2 (ChR2) has become a preferred tool for the targeted light-activation of neurons both in vitro and vivo [1][2][3][4] . Although wild-type (WT) ChR2 can be employed for light-induced depolarization, there is an ongoing search for ChR2 mutants with increased lightsensitivity for potential future clinical applications [5][6][7] .…”

Selective Manipulation of Neural Circuits

“…In contrast, halorhodopsin and archaerhodopsin inhibit neuronal activity. Halorhodopsin is a light-sensitive inward chloride pump that silences neuronal firing in response to yellow light (580 nm) [112]; archaerhodopsin is a proton pump responsive to yellow-green light (550 nm) [113].…”