Coherent Raman Scattering Unravelling Mechanisms Underlying Skull Optical Clearing for Through-Skull Brain Imaging.

Area of Science:

• Neuroscience
• Biomedical Optics
• Microscopy

Background:

• Studying mouse brain structures and functions in vivo requires optical access.
• Current methods for brain imaging involve invasive skull thinning or opening.
• The molecular mechanisms of mild skull optical clearing remain poorly understood.

Purpose of the Study:

• To unravel the molecular process of optical clearing in the mouse skull.
• To discover an optimal strategy for transforming an opaque skull into a transparent window.
• To enable deeper in vivo brain imaging.

Main Methods:

• Label-free hyperspectral stimulated Raman scattering (SRS) microscopy.
• Microspectroscopy for analyzing molecular composition.
• In vivo three-photon imaging.

Main Results:

• The molecular mechanisms underlying mouse skull optical clearing were elucidated.
• An optimal clearing strategy was identified, rendering the skull transparent.
• Vascular structures were imaged up to 850 μm deep in the mouse cortex.

Conclusions:

• Label-free SRS microscopy is effective for understanding tissue optical clearing.
• The discovered clearing strategy facilitates deep brain imaging in mice.
• Coherent Raman microspectroscopy shows potential for advancing future tissue clearing techniques.