Ultra-high density imaging arrays for diffuse optical tomography of human brain improve resolution, signal-to-noise, and information decoding

Markow, Z. E.; Trobaugh, J. W.; Richter, E. J.; Tripathy, K.; Rafferty, S. M.; Svoboda, A. M.; Schroeder, M. L.; Burns-Yocum, T. M.; Bergonzi, K. M.; Chevillet, M. A.; Mugler, E. M.; Eggebrecht, A. T.; Culver, J. P.

doi:10.1101/2023.07.21.549920

bioRxiv · 10.1101/2023.07.21.549920

Ultra-high density imaging arrays for diffuse optical tomography of human brain improve resolution, signal-to-noise, and information decoding

Markow, Z. E.·Trobaugh, J. W.·Richter, E. J.·Tripathy, K.·Rafferty, S. M.·Svoboda, A. M.·Schroeder, M. L.·Burns-Yocum, T. M.·Bergonzi, K. M.·Chevillet, M. A.·Mugler, E. M.·Eggebrecht, A. T.·Culver, J. P.

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Abstract

Functional magnetic resonance imaging (fMRI) has dramatically advanced non-invasive human brain mapping and decoding. Functional near-infrared spectroscopy (fNIRS) and high-density diffuse optical tomography (HD-DOT) non-invasively measure blood oxygen fluctuations related to brain activity, like fMRI, at the brain surface, using more-lightweight equipment that circumvents ergonomic and logistical limitations of fMRI. HD-DOT grids have smaller inter-optode spacing ([~]13 mm) than sparse fNIRS ([~]30 mm) and therefore provide higher image quality, with spatial resolution [~]1/2 that of fMRI. Herein, simulations indicated reducing inter-optode spacing to 6.5 mm would further improve image quality and noise-resolution tradeoff, with diminishing returns below 6.5 mm. We then constructed an ultra-high-density DOT system (6.5-mm spacing) with 140 dB dynamic range that imaged stimulus-evoked activations with 30-50% higher spatial resolution and repeatable multi-focal activity with excellent agreement with participant-matched fMRI. Further, this system decoded visual stimulus position with 19-35% lower error than previous HD-DOT, throughout occipital cortex.

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Markow, Z. E., Trobaugh, J. W., Richter, E. J., Tripathy, K., Rafferty, S. M., Svoboda, A. M., Schroeder, M. L., Burns-Yocum, T. M., Bergonzi, K. M., Chevillet, M. A., Mugler, E. M., Eggebrecht, A. T., Culver, J. P.. 2023-07-25. Ultra-high density imaging arrays for diffuse optical tomography of human brain improve resolution, signal-to-noise, and information decoding. https://doi.org/10.1101/2023.07.21.549920

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