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Simultaneous BOLD fMRI and fiber-optic calcium recording in rat neocortex

Nature Methods volume 9, pages 597–602 (2012)Cite this article

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Abstract

Functional magnetic resonance imaging (fMRI) based on blood oxygen level–dependent (BOLD) contrast is widely used for probing brain activity, but its relationship to underlying neural activity remains elusive. Here, we combined fMRI with fiber-optic recordings of fluorescent calcium indicator signals to investigate this relationship in rat somatosensory cortex. Electrical forepaw stimulation (1–10 Hz) evoked fast calcium signals of neuronal origin that showed frequency-dependent adaptation. Additionally, slower calcium signals occurred in astrocyte networks, as verified by astrocyte-specific staining and two-photon microscopy. Without apparent glia activation, we could predict BOLD responses well from simultaneously recorded fiber-optic signals, assuming an impulse response function and taking into account neuronal adaptation. In cases with glia activation, we uncovered additional prolonged BOLD signal components. Our findings highlight the complexity of fMRI BOLD signals, involving both neuronal and glial activity. Combined fMRI and fiber-optic recordings should help to clarify cellular mechanisms underlying BOLD signals.

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Figure 1: Setup for simultaneous fiber-optic calcium recording and fMRI.
Figure 2: Combined BOLD and fiber-optic measurements at various stimulation frequencies.
Figure 3: Comparison of fiber-optic signals and two-photon calcium imaging data.
Figure 4: Model reconstruction of BOLD changes from neuronal calcium responses.
Figure 5: Prolonged BOLD signal components in trials with glia activation.

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References

  1. Logothetis, N.K. What we can do and what we cannot do with fMRI. Nature 453, 869–878 (2008).

    Article  CAS  Google Scholar 

  2. Rudin, M. Molecular Imaging: Basic Principles and Applications in Biomedical Research (Imperial College Press, 2005).

  3. Heeger, D.J. & Ress, D. What does fMRI tell us about neuronal activity? Nat. Rev. Neurosci. 3, 142–151 (2002).

    Article  CAS  Google Scholar 

  4. Stephan, K.E., Weiskopf, N., Drysdale, P.M., Robinson, P.A. & Friston, K.J. Comparing hemodynamic models with DCM. Neuroimage 38, 387–401 (2007).

    Article  Google Scholar 

  5. Stefanovic, B., Schwindt, W., Hoehn, M. & Silva, A.C. Functional uncoupling of hemodynamic from neuronal response by inhibition of neuronal nitric oxide synthase. J. Cereb. Blood Flow Metab. 27, 741–754 (2007).

    Article  CAS  Google Scholar 

  6. Logothetis, N.K., Pauls, J., Augath, M., Trinath, T. & Oeltermann, A. Neurophysiological investigation of the basis of the fMRI signal. Nature 412, 150–157 (2001).

    Article  CAS  Google Scholar 

  7. Attwell, D. et al. Glial and neuronal control of brain blood flow. Nature 468, 232–243 (2010).

    Article  CAS  Google Scholar 

  8. Grewe, B.F. & Helmchen, F. Optical probing of neuronal ensemble activity. Curr. Opin. Neurobiol. 19, 520–529 (2009).

    Article  CAS  Google Scholar 

  9. Nedergaard, M., Rodriguez, J.J. & Verkhratsky, A. Glial calcium and diseases of the nervous system. Cell Calcium 47, 140–149 (2010).

    Article  CAS  Google Scholar 

  10. Stosiek, C., Garaschuk, O., Holthoff, K. & Konnerth, A. In vivo two-photon calcium imaging of neuronal networks. Proc. Natl. Acad. Sci. USA 100, 7319–7324 (2003).

    Article  CAS  Google Scholar 

  11. Adelsberger, H., Garaschuk, O. & Konnerth, A. Cortical calcium waves in resting newborn mice. Nat. Neurosci. 8, 988–990 (2005).

    Article  CAS  Google Scholar 

  12. Lee, J.H. et al. Global and local fMRI signals driven by neurons defined optogenetically by type and wiring. Nature 465, 788–792 (2010).

    Article  CAS  Google Scholar 

  13. Desai, M. et al. Mapping brain networks in awake mice using combined optical neural control and fMRI. J. Neurophysiol. 105, 1393–1405 (2011).

    Article  CAS  Google Scholar 

  14. Sydekum, E. et al. Functional reorganization in rat somatosensory cortex assessed by fMRI: elastic image registration based on structural landmarks in fMRI images and application to spinal cord injured rats. Neuroimage 44, 1345–1354 (2009).

    Article  Google Scholar 

  15. Kim, T., Masamoto, K., Fukuda, M., Vazquez, A. & Kim, S.G. Frequency-dependent neural activity, CBF, and BOLD fMRI to somatosensory stimuli in isoflurane-anesthetized rats. Neuroimage 52, 224–233 (2010).

    Article  Google Scholar 

  16. Kerr, J.N., Greenberg, D. & Helmchen, F. Imaging input and output of neocortical networks in vivo. Proc. Natl. Acad. Sci. USA 102, 14063–14068 (2005).

    Article  CAS  Google Scholar 

  17. Wang, X. et al. Astrocytic Ca2+ signaling evoked by sensory stimulation in vivo. Nat. Neurosci. 9, 816–823 (2006).

    Article  CAS  Google Scholar 

  18. Winship, I.R., Plaa, N. & Murphy, T.H. Rapid astrocyte calcium signals correlate with neuronal activity and onset of the hemodynamic response in vivo. J. Neurosci. 27, 6268–6272 (2007).

    Article  CAS  Google Scholar 

  19. Takano, T. et al. Astrocyte-mediated control of cerebral blood flow. Nat. Neurosci. 9, 260–267 (2006).

    Article  CAS  Google Scholar 

  20. Drew, P.J., Shih, A.Y. & Kleinfeld, D. Fluctuating and sensory-induced vasodynamics in rodent cortex extend arteriole capacity. Proc. Natl. Acad. Sci. USA 108, 8473–8478 (2011).

    Article  CAS  Google Scholar 

  21. Shen, Z., Lu, Z., Chhatbar, P.Y., O'Herron, P. & Kara, P. An artery-specific fluorescent dye for studying neurovascular coupling. Nat. Methods 9, 273–276 (2012).

    Article  CAS  Google Scholar 

  22. Silva, A.C., Koretsky, A.P. & Duyn, J.H. Functional MRI impulse response for BOLD and CBV contrast in rat somatosensory cortex. Magn. Reson. Med. 57, 1110–1118 (2007).

    Article  Google Scholar 

  23. Engelbrecht, C.J., Göbel, W. & Helmchen, F. Enhanced fluorescence signal in nonlinear microscopy through supplementary fiber-optic light collection. Opt Express 17, 6421–6435 (2009).

    Article  CAS  Google Scholar 

  24. Carmignoto, G. & Gomez-Gonzalo, M. The contribution of astrocyte signalling to neurovascular coupling. Brain Res. Rev. 63, 138–148 (2010).

    Article  CAS  Google Scholar 

  25. Calcinaghi, N. et al. Metabotropic glutamate receptor mGluR5 is not involved in the early hemodynamic response. J. Cereb. Blood Flow Metab. 31, e1–e10 (2011).

    Article  CAS  Google Scholar 

  26. Schummers, J., Yu, H. & Sur, M. Tuned responses of astrocytes and their influence on hemodynamic signals in the visual cortex. Science 320, 1638–1643 (2008).

    Article  CAS  Google Scholar 

  27. Dreier, J.P. The role of spreading depression, spreading depolarization and spreading ischemia in neurological disease. Nat. Med. 17, 439–447 (2011).

    Article  CAS  Google Scholar 

  28. Tian, L. et al. Imaging neural activity in worms, flies and mice with improved GCaMP calcium indicators. Nat. Methods 6, 875–881 (2009).

    Article  CAS  Google Scholar 

  29. Lütcke, H. et al. Optical recording of neuronal activity with a genetically encoded calcium indicator in anesthetized and freely moving mice. Front Neural Circuits 4, 9 (2010).

    PubMed  PubMed Central  Google Scholar 

  30. Atkin, S.D. et al. Transgenic mice expressing a cameleon fluorescent Ca2+ indicator in astrocytes and Schwann cells allow study of glial cell Ca2+ signals in situ and in vivo. J. Neurosci. Methods 181, 212–226 (2009).

    Article  CAS  Google Scholar 

  31. Garaschuk, O., Milos, R.I. & Konnerth, A. Targeted bulk-loading of fluorescent indicators for two-photon brain imaging in vivo. Nat. Protoc. 1, 380–386 (2006).

    Article  CAS  Google Scholar 

  32. Gruetter, R. Automatic, localized in vivo adjustment of all first- and second-order shim coils. Magn. Reson. Med. 29, 804–811 (1993).

    Article  CAS  Google Scholar 

  33. Flusberg, B.A. et al. Fiber-optic fluorescence imaging. Nat. Methods 2, 941–950 (2005).

    Article  CAS  Google Scholar 

  34. Engelbrecht, C.J., Johnston, R.S., Seibel, E.J. & Helmchen, F. Ultra-compact fiber-optic two-photon microscope for functional fluorescence imaging in vivo. Opt. Express 16, 5556–5564 (2008).

    Article  CAS  Google Scholar 

  35. Fu, L. & Gu, M. Fibre-optic nonlinear optical microscopy and endoscopy. J. Microsc. 226, 195–206 (2007).

    Article  CAS  Google Scholar 

  36. Nimmerjahn, A., Kirchhoff, F., Kerr, J.N. & Helmchen, F. Sulforhodamine 101 as a specific marker of astroglia in the neocortex in vivo. Nat. Methods 1, 31–37 (2004).

    Article  CAS  Google Scholar 

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Acknowledgements

We thank M. Thallmair and B. Weber for helpful comments on the manuscript. This work was supported by the National Competence Center in Research program Neural Plasticity and Repair (M.R. and F.H.), the EU Seventh Framework Programme (SPACEBRAIN, project 200873, F.H.), the Swiss SystemsX.ch initiative (Neurochoice project, F.H.) and the Swiss National Science Foundation (grant 126029, M.R.).

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Author notes

  1. Esther Sydekum & Christoph J Engelbrecht

    Present address: Present addresses: Novartis Pharma Schweiz, Bern, Switzerland (E.S.) and E. Blum & Co. Ltd., Patent and Trademark Attorneys, Zurich, Switzerland (C.J.E.).,

Authors and Affiliations

  1. Department of Neurophysiology, Brain Research Institute, University of Zurich, Zurich, Switzerland

    Kristina Schulz, Roland Krueppel, Christoph J Engelbrecht & Fritjof Helmchen

  2. Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland

    Kristina Schulz, Esther Sydekum, Christoph J Engelbrecht, Felix Schlegel, Markus Rudin & Fritjof Helmchen

  3. Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland

    Esther Sydekum, Felix Schlegel, Aileen Schröter & Markus Rudin

  4. Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland

    Markus Rudin

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Contributions

F.H. and M.R. designed the research. C.J.E. and R.K. developed the optical setup. K.S. and R.K. did two-photon imaging experiments. K.S., E.S., F.S. and A.S. carried out simultaneous measurements of fMRI BOLD and OGB-1 fiber-optic fluorescence signals. E.S. and K.S. analyzed these BOLD data. R.K., F.S. and F.H. performed Rhod-2 and Fluo-4 measurements and F.S. analyzed the BOLD data. K.S. analyzed fluorescence traces. K.S. and F.H. developed the simulation models and wrote the paper.

Corresponding author

Correspondence to Fritjof Helmchen.

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Schulz, K., Sydekum, E., Krueppel, R. et al. Simultaneous BOLD fMRI and fiber-optic calcium recording in rat neocortex. Nat Methods 9, 597–602 (2012). https://doi.org/10.1038/nmeth.2013

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