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ref: -0 tags: adaptive optics two photon microscopy date: 10-26-2021 18:17 gmt revision:1 [0] [head]

Recently I've been underwhelmed by the performance of adaptive optics (AO) for imaging head-fixed cranial-window mice. There hasn't been much of an improvement, despite significant optimization effort. This begs the question: where are AO microscopes used?

When the purpose of a paper is to explain and qualify an novel AO approach, the improvement is always good, >> 2x. Yet, in the one paper (first below) when the purpose was neuroscience, not optics, the results are less inspiring. Are the results from the optics papers cherry-picked?

Thalamus provides layer 4 of primary visual cortex with orientation- and direction-tuned inputs Wenzhi Sun, Zhongchao Tan, Brett D Mensh & Na Ji 2016 https://www.nature.com/articles/nn.4196

  • This is the primary (only?) paper where AO was used, but the focus was biology: measuring the tuning properties of thalamic boutons in mouse visual cortex. Which they did, well!
  • Surprisingly, the largest improvement was not from using AO, but rather from thinning the cranial window from 340um to 170um.
  • "With a 340-μm-thick cranial window, 70% of all boutons appeared to be non-responsive to visual stimuli and only 7% satisfied OS criteria. With a thinner cranial window of 170-μm thickness, we found that 31% of boutons satisfied OS criteria (of total n = 1,302, 5 mice), which was still substantially fewer than 48% OS boutons as determined when the same boutons (n = 1,477, 5 mice) were imaged after aberration correction by adaptive optics"

Direct wavefront sensing for high-resolution in vivo imaging in scattering tissue Kai Wang, Wenzhi Sun, Christopher T. Richie, Brandon K. Harvey, Eric Betzig & Na Ji, 2015 https://www.nature.com/articles/ncomms8276

  • Direct wavefront sensing using indocayanine green + Andor iXon 897 EMCCD Shack-Hartmann wavefront sensor (read: expensive).
  • Alpao DM97-15, basically the same as ours.
  • Fairly local wavefront corrections, see figure 2.
  • Also note that these wavefront corrections seem low-order, hence should be correctable via a DM

Multiplexed aberration measurement for deep tissue imaging in vivo Chen Wang, Rui Liu, Daniel E Milkie, Wenzhi Sun, Zhongchao Tan, Aaron Kerlin, Tsai-Wen Chen, Douglas S Kim & Na Ji 2014 https://www.nature.com/articles/nmeth.3068

  • Use a DMD (including a dispersion pre-compensator) to amplitude modulate phase ramps on a wavefront-modulating SLM. Each phase-ramp segment of the SLM was modulated at a different frequency, allowing for the optimal phase to be pulled out later through a Fourier transform.
  • Again, very good performance at depth in the mouse brain.