The technique, termed serial two-photon (STP) tomography, automates and standardises the process in which brain samples are divided into sections and then imaged sequentially at precise spatial orientations with two-photon microscopes.
‘The new technology should greatly facilitate the systematic study of neuroanatomy in mouse models of human brain disorders such as schizophrenia and autism,’ said project lead Pavel Osten, of Cold Spring Harbor Laboratory (CSHL), who performed the research in collaboration with colleagues at the Massachusetts Institute of Technology (MIT).
Tomography refers to any process that images an object section by section, by shooting penetrating waves through it. Computers powered by mathematical formulae reassemble the results to produce a three-dimensional rendering.
Two-photon imaging is a type used in biology laboratories, particularly in conjunction with fluorescent biomarkers, which can illuminate specific cell types or other anatomical features. The method allows deeper optical penetration into the tissue being sampled than conventional confocal microscopy.
STP tomography achieves the high-throughput fluorescence imaging of whole mouse brains via robotic integration of the two fundamental steps — tissue sectioning and fluorescence imaging.
One set of experiments tested the technology at different levels of resolution, where 10x magnification proved ‘sufficient to visualise the distribution and morphology of green-fluorescent protein-labelled neurons, including their dendrites and axons,’ said Osten.
Until now, means of obtaining such images — used in cutting-edge projects to map the mammalian brain — have been painstakingly slow and available only to a handful of highly specialised research teams.