Young zebrafish could provide information on nerve cell circuits for social behavior

Johannes Larsch receives NARSAD Young Investigator Grant

September 26, 2019

A look or a gesture is often enough to assess another person's mood and to adapt one's own behavior to it. People who are unable to interpret these social signals struggle to cope in society. Johannes Larsch from the Max Planck Institute of Neurobiology plans to investigate which signals trigger social behavior in juvenile zebrafish and how the brains and genomes of particularly social and non-social animals differ. The Brain & Behavior Research Foundation will support the study.

Among young zebrafish there are introverts and extroverts. Johannes Larsch aims to investigate the underlying differences in their brains and genome.

Even among zebrafish, there are introverts and extroverts. This becomes evident at just three weeks of age, when the baby fish begin to interact with other zebrafish and to form shoals. “Even siblings, who are genetically very similar, show distinct differences in the level of persistence with which they interact with others,” says Johannes Larsch, who now intends to investigate the fundamental reasons for these behavioral differences in the brain.

Larsch has developed an experimental setup that documents the fish’s interactions with a virtual dot. A previous study showed that the fish identify it a shoal member by its characteristic movements. The degree to which the fish actively follow the dot gives an indication of their social competence. Larsch can thus pick fish from either end of the social spectrum for further study. Breeding particularly social or non-social fish, respectively, produces offspring that exhibit the social skills of their parents in an even more pronounced fashion.

If a dot moves like a zebrafish it triggers shoaling in young fish. They follow the dot more or less perserving.

The fish’s social behavior therefore appears to have a hereditary component, which should be detectable in their brain and genome. In order to investigate differences in the neuronal activity of gregarious or shy fish, Johannes Larsch and his colleagues in Herwig Baier's Department intend to look directly into the fish’s brains.

Young zebrafish are almost transparent. Using the latest genetic methods, the activity of individual nerve cells or brain areas can be observed under the microscope while the fish interacts with the dot. “The results could also provide us with information on processes in the human brain in psychosocial disorders such as autism or schizophrenia,” says Larsch.

He also hopes to pursue this aspect at the genome level, planning to investigate fish that lack specific genes associated with schizophrenia in humans. “I don’t believe we could describe a fish as schizophrenic,” explains Larsch. “But they could prove to be a good model for investigating the molecules that play a role in this, and other, disorders.”

The Awardee

Johannes Larsch studied Biology at the University of Konstanz, Germany and gained his PhD at the Rockefeller University in New York. For his postdoctoral training, he joined Herwig Baier’s department at the Max Planck Institute of Neurobiology in 2015. Starting in 2018, he investigates as project group leader the neuronal foundations of social behavior.

The NARSAD Young Investigator Grant

NARSAD research funds, awarded by the Brain & Behavior Research Foundation is a high distinction for neurobiological research relating to mental health. The Young Investigator Grant supports ambitious projects of young scientists with 70,000 US Dollars for the duration of two years.

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