New Method to Map Miniature Brain Circuits


Source: The Francis Crick Institute

Summary: Researchers, in a feat of nanoengineering, have developed a new technique to map electrical circuits in the brain far more comprehensively than ever before.


A dedicated group of neurons are found in the brain which connects up in microcircuits help us process information about things we see, smell and taste. To know how many and what type of cells make up these microcircuits, scientists need a deeper understanding of how the brain computes complex information about the world around us. But the available current techniques have failed to paint a complete picture. Researchers from the Francis Crick Institute in a feat of nanoengineering, have developed a new technique to map electrical circuits in the brain far more comprehensively than ever before. This new technique overcomes the previous limitations and has enabled them to map out all 250 cells that make up a microcircuit in part of a mouse brain that processes smell – something that has never been achieved before. The study findings were published in the journal Nature Communications.

A group of neurons connect to form microcircuits

Credit: The Francis Crick Institute

Traditionally, scientists have either used color-tagged viruses or charged dyes with an applied electric current to stain brain cells, but these approaches either don’t label all cells or they damage the surrounding tissue. In this new technique, researchers created a series of tiny holes near the end of a micropipette using nano-engineering tools, the team found that they could use charged dyes but distribute the electrical current over a wider area, to stain cells without damaging them. They could stain up to 100% of the cells in the microcircuit they were investigating which is not possible in the methods that use viral vectors. They also managed to work out the proportions of different cell types in this circuit, which may give clues into the function of this part of the brain.

Micropipette with holes to distribute electric current

Model (left) and high-resolution image (right) of the nanoengineered micropipette with holes to distribute electrical current. Credit: Daniel Schwarz

Group Leader, Andreas Schaefer, said, “We’re obviously working at a really small scale, but as the brain is made up of repeating units, we can learn a lot about how the brain works as a computational machine by studying it at this level. Now that we have a tool of mapping these tiny units, we can start to interfere with specific cell types to see how they directly control behaviour and sensory processing.”


More Information: D. Schwarz et al, “Architecture of a mammalian glomerular domain revealed by novel volume electroporation using nanoengineered microelectrodes”, Nature Communications (2018). DOI: 10.1038/s41467-017-02560-7 


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