title: Scanless functional imaging of hippocampal networks using patterned two-photon illumination through GRIN lenses.
abstract: Patterned illumination through the phase modulation of light is increasingly recognized as a powerful tool to investigate biological tissues in combination with two-photon excitation and light-sensitive molecules. However, to date two-photon patterned illumination has only been coupled to traditional microscope objectives, thus limiting the applicability of these methods to superficial biological structures. Here, we show that phase modulation can be used to efficiently project complex two-photon light patterns, including arrays of points and large shapes, in the focal plane of graded index (GRIN) lenses. Moreover, using this approach in combination with the genetically encoded calcium indicator GCaMP6, we validate our system performing scanless functional imaging in rodent hippocampal networksin vivo ~1.2 mm below the brain surface. Our results open the way to the application of patterned illumination approaches to deep regions of highly scattering biological tissues, such as the mammalian brain.
authors.affiliation: Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Moretti
authors.affiliation: Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Nanostructures Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Antonini
authors.affiliation: Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Bovetti
authors.affiliation: Nanostructures Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Carlo
authors.initials: C
authors.lastname: Liberale
authors.affiliation: Optical Approaches to Brain Function Laboratory, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Fellin
keywords: (120.5060) Phase modulation; (170.2150) Endoscopic imaging; (170.2520) Fluorescence microscopy; (180.4315) Nonlinear microscopy