title: Monitoring synaptic and neuronal activity in 3D with synthetic and genetic indicators using a compact acousto-optic lens two-photon microscope.
abstract: BACKGROUND
  Two-photon microscopy is widely used to study brain function, but conventional microscopes are too slow to capture the timing of neuronal signalling and imaging is restricted to one plane. Recent development of acousto-optic-deflector-based random access functional imaging has improved the temporal resolution, but the utility of these technologies for mapping 3D synaptic activity patterns and their performance at the excitation wavelengths required to image genetically encoded indicators have not been investigated.
  
  
  METHODS
  Here, we have used a compact acousto-optic lens (AOL) two-photon microscope to make high speed [Ca(2+)] measurements from spines and dendrites distributed in 3D with different excitation wavelengths (800-920 nm).
  
  
  RESULTS
  We show simultaneous monitoring of activity from many synaptic inputs distributed over the 3D arborisation of a neuronal dendrite using both synthetic as well as genetically encoded indicators. We confirm the utility of AOL-based imaging for fast in vivo recordings by measuring, simultaneously, visually evoked responses in 100 neurons distributed over a 150 μm focal depth range. Moreover, we explore ways to improve the measurement of timing of neuronal activation by choosing specific regions within the cell soma.
  
  
  METHODS
  These results establish that AOL-based 3D random access two-photon microscopy has a wider range of neuroscience applications than previously shown.
  
  
  CONCLUSIONS
  Our findings show that the compact AOL microscope design has the speed, spatial resolution, sensitivity and wavelength flexibility to measure 3D patterns of synaptic and neuronal activity on individual trials.
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address: t.fernandez@ucl.ac.uk.
authors.forename: Tomás
authors.initials: T
authors.lastname: Fernández-Alfonso
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address: k.nadella@ucl.ac.uk.
authors.forename: K M Naga Srinivas
authors.initials: KM
authors.lastname: Nadella
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address: florencia.iacaruso@gmail.com.
authors.forename: M Florencia
authors.initials: MF
authors.lastname: Iacaruso
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address: bruno.pichler@gmx.de.
authors.forename: Bruno
authors.initials: B
authors.lastname: Pichler
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address: h.ros@ucl.ac.uk.
authors.forename: Hana
authors.initials: H
authors.lastname: Roš
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address: p.a.kirkby@ucl.ac.uk.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kirkby
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address: a.silver@ucl.ac.uk.
authors.forename: R Angus
authors.initials: RA
authors.lastname: Silver
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002540:Cerebral Cortex / Q000502:physiology; D003712:Dendrites / Q000502:physiology; D049229:Dendritic Spines / Q000502:physiology; D018274:Electroporation; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods*; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D036641:Microscopy, Fluorescence, Multiphoton / Q000295:instrumentation / Q000379:methods; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology; D013995:Time; D014796:Visual Perception / Q000502:physiology; D056969:Voltage-Sensitive Dye Imaging / Q000295:instrumentation / Q000379:methods
chemical_list: D002118:Calcium
keywords: 3D functional imaging; Acousto-optic deflectors; Acousto-optic lens; Calcium imaging; Population imaging; Synaptic activity mapping; Two-photon imaging