Three-dimensional analysis of human brain cytoarchitectonics by means of a SWITCH/TDE-combined clearing method

The three-dimensional reconstruction of large volumes of the human neural networks at cellular resolution is one of the biggest challenges of our days. Commonly, fine slices of samples marked with colorimetric techniques are individually imaged. This approach in addition to being time-consuming does not consider space cell organization, leading to loss of information. The aim of this work was to develop a methodology that allows analyzing the cytoarchitecture of the human brain in three dimensions at high resolution. In particular, we exploit the possibility of combining high-resolution 3D imaging techniques with clearing methodologies. We successfully integrate the SWITCH immunohistochemistry technique with the TDE clearing method to image a large volume of human brain tissue with two-photon fluorescence microscopy. In conclusion, this new approach enables to characterize large human brain specimens with high-resolution optical techniques, giving the possibility to expand the histological studies to the third dimension.