From electrical networks to neural networks
9/29/14

In May 2014, a team of seven researchers from the 'Systems and Modelling' Research Unit at the University of Liège Faculty of Applied Sciences won the 'Neural Connectomics Challenge: From Imaging to Connectivity'. The aim of this prestigious challenge was to predict the map of connections between neurons in the brain. The team presented its methodology and results during a workshop in September. Interview with the three prize-winners - Damien ErnstPierre Geurts and Antonio Sutera - who only found out what a connectome was when they signed up for the competition!

How did your 'Connectomics Challenge' adventure begin?

network connectomesPierre: It was Antonio who discovered the competition on a website which listed data analysis competitions (www.kaggle.com). He talked to us about the Connectomics Challenge and we gave him the green light to sign up for it.  Several of our research subjects were close to the issues addressed by this competition. For example, we have  studied gene networks and most of the approaches used in this context can be applied to other types of networks, regardless of their nature.

Damien: The team consisted of five research engineers from the University of Liège's Montefiore Institute in the Department of Electrical Engineering and Computer Science in the Faculty of Applied Sciences. We are a real bunch of friends, some of us specialising in the development of future electrical networks (smart grids) while the others analyse and develop automatic learning algorithms.

Antonio: Arnaud, Vincent, Zixiao, Gilles and I share the same office and this allowed us to compare our ideas and to stimulate our creativity.

We've already heard of genomes and proteomes but what is a connectome?

Damien: It's true that before we signed up for this competition, even we had never heard about connectomes!

Antonio: It is a representation of the structure of the connections between the neurons which make up the brain.

Pierre: The basic structure is very similar from one individual to the next, but we each have our own connectome. In the context of the Connectomics Challenge, we had to work on a group of 1,000 neurons.

What were the various stages of the competition?

Pierre: The aim was to find out how to pair neurons and connect them within the network, based on data which artificially simulated brain activity. We thought we could base our work on a method which we had already designed to study gene networks, but it didn't work. Therefore, we had to develop a new approach.

Antonio: Each neuron has an electrical signal and we measured the correlation between the signals for all neuron pairs.  But we had to be careful, because two neurons may have a similar signal without being connected to one another. We therefore developed an approach which could take into account all the other neurons.

Damien: We received the data in March. It was really exciting because we could follow the developments of the other 143 teams from prestigious universities on-line. We submitted our results in May and were announced as the winners at the end of the competition. We presented our methodology and our results at a workshop in September.(1)

(1)    Antonio Sutera, Arnaud Joly, Vincent François-Lavet, Gilles Louppe, Damien Ernst and Pierre Geurts. Simple connectome inference from partial correlation statistics in calcium imaging. JMLR: Workshop and Conference Proceedings (2014)1–11.  Neural Connectomics Workshop.

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