1. Neuroscience

Extended field-of-view ultrathin microendoscopes for high-resolution two-photon imaging with minimal invasiveness

  1. Tommaso Fellin  Is a corresponding author
  2. Andrea Antonini
  3. Andrea Sattin
  4. Monica Moroni
  5. Serena Bovetti
  6. Claudio Moretti
  7. Francesca Succol
  8. Angelo Forli
  9. Dania Vecchia
  10. Vijayakumar p Rajamanickam
  11. Andrea Bertoncini
  12. Stefano Panzeri
  13. Carlo Liberale
  1. Italian Institute of Technology, Italy
  2. KAUST, Saudi Arabia
  3. Istituto Italiano di tecnologia, Italy
https://doi.org/10.7554/eLife.58882
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  1. Tommaso Fellin
  2. Andrea Antonini
  3. Andrea Sattin
  4. Monica Moroni
  5. Serena Bovetti
  6. Claudio Moretti
  7. Francesca Succol
  8. Angelo Forli
  9. Dania Vecchia
  10. Vijayakumar p Rajamanickam
  11. Andrea Bertoncini
  12. Stefano Panzeri
  13. Carlo Liberale
(2020)
Extended field-of-view ultrathin microendoscopes for high-resolution two-photon imaging with minimal invasiveness
eLife 9:e58882.
https://doi.org/10.7554/eLife.58882
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  3. Download .RIS

Abstract

Imaging neuronal activity with high and homogeneous spatial resolution across the field-of-view (FOV) and limited invasiveness in deep brain regions is fundamental for the progress of neuroscience, yet is a major technical challenge. We achieved this goal by correcting optical aberrations in gradient index lens-based ultrathin (< 500 μm) microendoscopes using aspheric microlenses generated through 3D-microprinting. Corrected microendoscopes had extended FOV (eFOV) with homogeneous spatial resolution for two-photon fluorescence imaging and required no modification of the optical set-up. Synthetic calcium imaging data showed that, compared to uncorrected endoscopes, eFOV-microendoscopes led to improved signal-to-noise ratio and more precise evaluation of correlated neuronal activity. We experimentally validated these predictions in awake head-fixed mice. Moreover, using eFOV-microendoscopes we demonstrated cell-specific encoding of behavioral state-dependent information in distributed functional subnetworks in a primary somatosensory thalamic nucleus. eFOV-microendoscopes are, therefore, small-crosssection ready-to-use tools for deep two-photon functional imaging with unprecedentedly high and homogeneous spatial resolution.

Data availability

The datasets shown in Figures 4, 6, 7 and corresponding figure supplements are available at:https://data.mendeley.com/datasets/wm6c5wzs4c/draft?a=56f1660e-a036-40ee-83ef-458dc2457b6aThe software used in this paper to generate and analyze artificial t-series is available at: https://github.com/moni90/eFOV_microendoscopes_simNumerical data for graphs represented in figures 3-7, figure 2-figure supplement 2-4, figure 3-figure supplement 4, figure 4-figure supplement 1-2 are provided as source data.

The following data sets were generated

Article and author information

Author details

  1. Tommaso Fellin

    Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
    For correspondence
    tommaso.fellin@iit.it
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2718-7533

  2. Andrea Antonini

    Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.

  3. Andrea Sattin

    Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.

  4. Monica Moroni

    CNCS, Italian Institute of Technology, ROVERETO, Italy
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1852-7217

  5. Serena Bovetti

    CNCS, Italian Institute of Technology, ROVERETO, Italy
    Competing interests
    The authors declare that no competing interests exist.

  6. Claudio Moretti

    Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.

  7. Francesca Succol

    Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.

  8. Angelo Forli

    Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.

  9. Dania Vecchia

    Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.

  10. Vijayakumar p Rajamanickam

    BESE, KAUST, Thuwal, Saudi Arabia
    Competing interests
    The authors declare that no competing interests exist.

  11. Andrea Bertoncini

    BESE, KAUST, Thuwal, Saudi Arabia
    Competing interests
    The authors declare that no competing interests exist.

  12. Stefano Panzeri

    Center for Neuroscience and Cognitive Systems, Istituto Italiano di tecnologia, Rovereto, Italy
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1700-8909

  13. Carlo Liberale

    BESE, KAUST, Thuwal, Saudi Arabia
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5653-199X

Funding

European Research Council (NEURO-PATTERNS)

  • Tommaso Fellin

IIT interdisciplinary grant

  • Tommaso Fellin

IIT interdisciplinary grant

  • Carlo Liberale

KAUST (BAS/1/1064-01-01)

  • Carlo Liberale

NIH Brain Initiative (NS090576)

  • Tommaso Fellin

NIH Brain Initiative (NS107464)

  • Tommaso Fellin

NIH Brain Initiative (NS107464)

  • Stefano Panzeri

NIH Brain Initiative (NS109961)

  • Stefano Panzeri

FP7 (DESIRE)

  • Tommaso Fellin

FIRB (RBAP11X42L)

  • Tommaso Fellin

Flag-Era JTC Human Brain Project (SLOW-DYN)

  • Tommaso Fellin

Flag-Era JTC Human Brain Project (SLOW-DYN)

  • Stefano Panzeri

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: Experimental procedures involving animals have been approved by the Istituto Italiano di Tecnologia Animal Health Regulatory Committee, by the National Council on Animal Care of the Italian Ministry of Health (authorization # 1134/2015-PR, # 689/2018-PR) and carried out according to the National legislation (D.Lgs. 26/2014) and to the legislation of the European Communities Council Directive (European Directive 2010/63/EU).

Copyright

© 2020, Fellin et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Tommaso Fellin
  2. Andrea Antonini
  3. Andrea Sattin
  4. Monica Moroni
  5. Serena Bovetti
  6. Claudio Moretti
  7. Francesca Succol
  8. Angelo Forli
  9. Dania Vecchia
  10. Vijayakumar p Rajamanickam
  11. Andrea Bertoncini
  12. Stefano Panzeri
  13. Carlo Liberale
(2020)
Extended field-of-view ultrathin microendoscopes for high-resolution two-photon imaging with minimal invasiveness
eLife 9:e58882.
https://doi.org/10.7554/eLife.58882

Share this article

https://doi.org/10.7554/eLife.58882

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Further reading

    1. Neuroscience

    Aberration correction in long GRIN lens-based microendoscopes for extended field-of-view two-photon imaging in deep brain regions

    Andrea Sattin, Chiara Nardin ... Tommaso Fellin
    Research Advance

    Two-photon (2P) fluorescence imaging through gradient index (GRIN) lens-based endoscopes is fundamental to investigate the functional properties of neural populations in deep brain circuits. However, GRIN lenses have intrinsic optical aberrations, which severely degrade their imaging performance. GRIN aberrations decrease the signal-to-noise ratio (SNR) and spatial resolution of fluorescence signals, especially in lateral portions of the field-of-view (FOV), leading to restricted FOV and smaller number of recorded neurons. This is especially relevant for GRIN lenses of several millimeters in length, which are needed to reach the deeper regions of the rodent brain. We have previously demonstrated a novel method to enlarge the FOV and improve the spatial resolution of 2P microendoscopes based on GRIN lenses of length <4.1 mm (Antonini et al., 2020). However, previously developed microendoscopes were too short to reach the most ventral regions of the mouse brain. In this study, we combined optical simulations with fabrication of aspherical polymer microlenses through three-dimensional (3D) microprinting to correct for optical aberrations in long (length >6 mm) GRIN lens-based microendoscopes (diameter, 500 µm). Long corrected microendoscopes had improved spatial resolution, enabling imaging in significantly enlarged FOVs. Moreover, using synthetic calcium data we showed that aberration correction enabled detection of cells with higher SNR of fluorescent signals and decreased cross-contamination between neurons. Finally, we applied long corrected microendoscopes to perform large-scale and high-precision recordings of calcium signals in populations of neurons in the olfactory cortex, a brain region laying approximately 5 mm from the brain surface, of awake head-fixed mice. Long corrected microendoscopes are powerful new tools enabling population imaging with unprecedented large FOV and high spatial resolution in the most ventral regions of the mouse brain.