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Looking at “how” neurones connect

Controlling single neurons using optogenetics. Credit: MIT

The number of tools at scientists disposal to look into the brain in their attempt to understand it keeps growing. Projects like “the Human Connectome” are trying to map all connections among the billions and billions of neurones and eventually they will succeed.

However the mapping resulting from those projects is a static one. Knowing that a bunch of neurones are connected is not telling anything about how they actually work. Is there a leading neurone steering the others? Are they independently churning signals that ultimately result in a change state that is perceivable at a conscious level or that influences subsequent processing?

To answer these types of questions you need to see neurones “at work”. fMRI provides us with a view of working neurones but its resolution is really low (you see a brain area “lighting up” but that contains millions of neurones with an undetectable mix of some active and some inactive. Even worse, there is a delay between the activation of neurones in response to a trigger and the actual detection of “something is happening”.

Optogenetics provides a much more precise image of neural areas, although it is still not what would really be needed. Optogenetics works by “infecting” neurones with foreign genes that direct the neurone to manufacture a specific protein that can be activated by a laser beam or that luminesces when the neurone is active. Although resolution with Optogenetics is much better than fMRI it still involves many neurones, the laser beam shines on and activates many neurones at the same time. This does not allow scientists to understand the relations among them.

Here comes the news from a team of researchers at MIT in Boston and Paris Descartes University in Paris. The researchers have managed to create a tool, still based on optogenetics, that gets rid of today’s limitations allowing scientists to look at the neurones interactions with a single neurone resolution and accurate temporal visibility. It becomes possible to see which neurone is initiating an action, which is/are taking up the signals generated and how the network evolves over time.

The feat has been accomplished by finding specific proteins (somatic channelrhodopsin) that can work with optogenetics (can be generated by infecting neurones and activated by a laser beam) and that remains in the body of a single neurone. The laser beam activates the protein within a millisecond, and this time remains constant even when several subsequent activations take place.

About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. Until April 2017 he led the EIT Digital Italian Node and then was head of the Industrial Doctoral School of EIT Digital up to September 2018. Previously, up to December 2011 he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the New Initiative Committee and co-chairs the Digital Reality Initiative. He is a member of the IEEE in 2050 Ad Hoc Committee. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books.