A new way of making slices of brain transparent

Three-dimensional view of stained hippocampus showing fluorescent-expressing neurons (green), connecting interneurons (red) and supporting glia (blue), created with the Stanford CLARITY technique. Credit: Deisseroth lab

Progress in understanding the physical underpinning of mental disorders leverages on better and better techniques to study the brain structure. This is done by slicing the brain (of dead patients, of course) and studying the "architecture", shape and content of the brain.

To study the architecture, that is the connectivity among the neurones and to identify neural "circuits" you need to have relatively thick slices so that connections and their spatial structure can be seen. Of course, in order to "see" through this thick slice you have to render it transparent.

There are already a number of techniques to do this and the images that have been taken are wonderful (see the second photo). However, the process to make the slice transparent alters the structure and therefore complicates the study of the image.

Here comes this news from RIKEN Brain Science Institute in Japan.  Researchers at the institute have been able to find an optical technique to make brain slices transparent to the electron microscope preserving the structure of the cells, their connectivity and their spatial relations.

They have used a solution of sorbitol and urea to create the desired transparency. In addition the sample obtained can be stained with specific "colours" that bind to specific cells or proteins, allowing the "rendering". As an example, in the first photo one can see the amyloid plaques that are typical of Alzheimer disease.

The trail is still long, but bettering technologies for looking into the structure of the brain gives a boost to our understanding on the relation of structure anomalies and specific abnormal behaviour. At the same time scientists have to understand why such structures happens and finally find a way to avoid it or to fix it. Several more decades of study and experimentation but it is now clear that it is a matter of "when" not "if".

Also interesting to notice that all of this is made possibile by software and communications, sharing of intermediate results to harvest global understanding. ICT is one of the fundamental tools in our quest.

Author - Roberto Saracco

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