Light-guided sectioning for precise in situ localization and tissue interface analysis for brain-implanted optical fibers and GRIN lenses

• Published in: Cell reports (Cambridge) Vol. 36; no. 13; p. 109744
• Main Authors: Kahan, Anat, Greenbaum, Alon, Jang, Min J., Robinson, J. Elliott, Cho, Jounhong Ryan, Chen, Xinhong, Kassraian, Pegah, Wagenaar, Daniel A., Gradinaru, Viviana
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28.09.2021; Elsevier
• Subjects: Animals; Brain - physiology; chronic implants; clearing; fiber photometry; GRIN lens; Head - physiology; histology; Lens, Crystalline - physiology; Lenses; Mice; Neurons - physiology; Optical Fibers; optogenetics; Photons; Refractometry - methods; two-photon imaging; fiber photometry; chronic implants; two-photon imaging; histology; optogenetics; clearing; GRIN lens
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2021.109744

Optical implants to control and monitor neuronal activity in vivo have become foundational tools of neuroscience. Standard two-dimensional histology of the implant location, however, often suffers from distortion and loss during tissue processing. To address that, we developed a three-dimensional post hoc histology method called “light-guided sectioning” (LiGS), which preserves the tissue with its optical implant in place and allows staining and clearing of a volume up to 500 μm in depth. We demonstrate the use of LiGS to determine the precise location of an optical fiber relative to a deep brain target and to investigate the implant-tissue interface. We show accurate cell registration of ex vivo histology with single-cell, two-photon calcium imaging, obtained through gradient refractive index (GRIN) lenses, and identify subpopulations based on immunohistochemistry. LiGS provides spatial information in experimental paradigms that use optical fibers and GRIN lenses and could help increase reproducibility through identification of fiber-to-target localization and molecular profiling. [Display omitted] •LiGS provides precise optical implant localization and surrounding tissue analysis•Optical fiber positioning errors are correlated with calcium signal strength•Glial scar formation around the optical implant is visualized in the brain•Post hoc cell registration with two-photon calcium imaging and molecular features Kahan et al. describe a 3D histology method (LiGS) to investigate with high fidelity the vicinity of an intact optical implant (e.g., GRIN lenses and optical fibers). LiGS is compatible with immunohistochemistry and single-molecule imaging. With the use of two-photon microscopy, LiGS can also link the functional properties of cells to their molecular identity.