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Germán Sumbre takes a plunge into the depths of the zebrafish brain

The activity of the zebrafish brain is beginning to reveal its secrets to Germán Sumbre, Inserm Research Director at the elite higher education establishment Ecole Normale Supérieure (ENS). Thanks to two grants from the European Research Council (ERC) - a Starting Grant in 2009 and a Consolidator Grant in 2016 - Germán Sumbre has been able to study the neuronal dynamics of these model fish both before sensory stimulation and after, and also when in a state of sensory deprivation, to find out just what is going on inside their heads…

German Sumbre

How does the brain react when an object is seen? How does it code the perception of this signal? And then what changes in terms of neuronal activity?  These are the questions that prompted Germán Sumbre, a young researcher having only just been hired by Inserm, to apply for ERC funding in 2009 . With funding from the ATIP-Avenir program, received the same year, he was able to set up a team at the Biology Institute of the ENS.

During his post-doctoral studies at the University of California, Berkeley in the US, he worked on temporal perception in zebrafish. When these fish were subjected to visual stimuli at different time intervals, he observed very high variability in their neuronal activity, which prompted him to investigate further. He approached the ERC with a proposal to discover whether the brain's intrinsic activity modulates sensory response. In other words, he wanted to describe the spontaneous functioning of the brain that precedes the sight of an object, and to find out whether it modifies the activity induced by the observation of that object. He would continue to work with the zebrafish, the only vertebrate model in which it is possible to observe neuronal activity in real time in the whole brain, and in an intact moving animal. 

Convinced by the project, the ERC awarded him approximately two million euros for five years,  enabling the researcher to recruit four post-doctoral students simultaneously. "They worked on parallel projects, with multidisciplinary approaches. This generated many interactions, the results of which were more fruitful than if they had been hired one after the other.  That's one of the immense advantages of such a large amount of funding", he added.  The researcher and his team conducted many experiments on spontaneous neuronal activity, but also in response to various visual stimuli, optical illusions, or gustatory stimuli. Little by little, they described the neuronal phenomena observed.

Funding for a second project on brain activity at rest and spontaneous movements

In 2014, as the ERC funding was nearing its end, Germán Sumbre decided to set up a second project, to study the spontaneous activity of the brain at rest (in the absence of any sensory stimulation) and the occurrence of spontaneous movements. "The brain is continually active, even when the animal is isolated from the outside world.  And this activity is not just what we might call background noise but veritable rich electrical activity at rest.  And this raises two questions, which are how is a spontaneous behavior coded from the neuronal point of view and what are the mechanisms that allow the emergence of neuronal activity predictive of that movement?",  he mused.  The relevance and conscientiousness of his research found a positive reception at the ERC, with the awarding of a second grant, to run from 2016 to 2021.

Germán Sumbre has already described a very clear temporal and spatial structure of this activity at rest.  Research which would not have progressed as far without the ERC. “It changed everything, it meant I could explore several dimensions at once, that I could buy the equipment needed for the experiments...  Not just that but ERC funding also brings a certain level of renown for the laboratory.  All of which is needed to conduct high-level research", he concluded. 

Find out more about Germán Sumbre and his research work
Germán Sumbre leads the Neuroéthologie du poisson-zèbre (Zebrafish neuroethology) team at Inserm Unit 1024/CNRS/ENS, in Paris.

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