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Rapid volumetric optoacoustic imaging of neural dynamics across the mouse brain

Abstract

Efforts to scale neuroimaging towards the direct visualization of mammalian brain-wide neuronal activity have faced major challenges. Although high-resolution optical imaging of the whole brain in small animals has been achieved ex vivo, the real-time and direct monitoring of large-scale neuronal activity remains difficult, owing to the performance gap between localized, largely invasive, optical microscopy of rapid, cellular-resolved neuronal activity and whole-brain macroscopy of slow haemodynamics and metabolism. Here, we demonstrate both ex vivo and non-invasive in vivo functional optoacoustic (OA) neuroimaging of mice expressing the genetically encoded calcium indicator GCaMP6f. The approach offers rapid, high-resolution three-dimensional snapshots of whole-brain neuronal activity maps using single OA excitations, and of stimulus-evoked slow haemodynamics and fast calcium activity in the presence of strong haemoglobin background absorption. By providing direct neuroimaging at depths and spatiotemporal resolutions superior to optical fluorescence imaging, functional OA neuroimaging bridges the gap between functional microscopy and whole-brain macroscopy.

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All custom code generated for this study can be obtained from the corresponding authors on reasonable request.

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The authors declare that all data supporting the findings of this study are available within the paper and its Supplementary Information. All datasets generated during this study are available from the corresponding authors.

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Acknowledgements

The authors acknowledge grant support from the European Research Council (under grant agreement ERC-2015-CoG-682379) and the US National Institutes of Health (grants R21-EY026382 and UF1-NS107680). We also acknowledge the help of N. Tritsch and L. Mcley with reading and commenting on the manuscript.

Author information

S.G., O.D., B.M.L., M.A.H. and X.L.D.-B. performed the experiments. S.G., O.D., B.M.L., J.R., M.A.H. and X.L.D.-B. analysed and processed the data. S.G., X.L.D.-B., S.S. and D.R. validated the data analysis. S.G., S.S. and D.R. designed and supervised the study. All authors contributed to writing the manuscript.

Competing interests

The authors declare no competing interests.

Correspondence to Daniel Razansky.

Supplementary information

  1. Supplementary Information

    Supplementary figures and video captions.

  2. Reporting Summary

  3. Supplementary Video 1

    OA calcium activity map in a single 2D slice located at an approximate depth of 1 mm in the mouse brain.

  4. Supplementary Video 2

    OA calcium activity in a single 2D slice located at an approximate depth of 0.5 mm in the mouse brain.

  5. Supplementary Video 3

    Haemodynamic responses across the entire mouse cortex in response to paw stimulation.

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Further reading

Fig. 1: Bi-modal OA and fluorescence imaging of isolated brains.
Fig. 2: Whole-brain volumetric OA imaging of neuronal activation in the isolated brain model.
Fig. 3: Non-invasive imaging of the GCaMP6f brain in vivo.
Fig. 4: Non-invasive imaging of somatosensory-evoked rapid calcium transients in the GCaMP6f brain in vivo.
Fig. 5: Comparison of GCaMP6f and GCaMP6s responses to electrical stimulation of the right or left hind paw.