Scientists at the Swiss Light Source SLS have succeeded in mapping a piece of brain tissue in 3D at unprecedented resolution using X-rays – non-destructively. The breakthrough overcomes a long-standing technological barrier that had limited the use of X-rays for such studies. With the SLS upgrade now complete, the path lies open to imaging much larger samples of brain tissue at high resolution – and to gaining new understanding of its complex architecture. The study, a collaboration between Paul Scherrer Institute PSI and the Francis Crick Institute in the UK, is published in Nature Methods.
“The brain is one of the most complex biological systems in the world,” says Adrian Wanner, who leads the Structural Neurobiology research group at Paul Scherrer Institute PSI. How neurons are wired together is what his group are trying to unravel – a field known as connectomics.
He explains: “Take the liver: we know of about 40 cell types. We know how they are arranged. We know their functions. This is not true for the brain. And so, one could ask, what is the difference between the brain and the liver? If we look at a cell body in the brain and the liver, it’s not easy to distinguish the two. They both have a nucleus, an endoplasmic reticulum – they both have the same intercellular machinery, the same molecules, the same types of proteins. This is not the difference. What is really different is how the brain cells are organised and connected.”
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Image: One cubic millimetre of brain tissue contains about 100 000 neurons, connected through some 700 million synapses and 4 kilometres of ‘cabling’. This complex 3D wiring underlies brain function – yet is extraordinarily difficult to study.
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