Someone to swim with

When the young fish complete the larval stage, at the age of about four weeks, and reach a length of one centimeter , They begin to attach to other fish. While they do not swim in beautifully arranged bands like the lunar fishes in the Disney and Pixar animated film, “Finding Nemo,” they do show a distinct tendency to swim in groups. Like humans, they also have good reasons to look for companionship – group swimming gives them benefits in searching for food, overcoming water currents, avoiding lunatics and finding mating partners. But to conduct a group, zebras must be able to decipher visual and social stimuli: for example, know how to distinguish between “friends” and “enemies” – that is, identify their species and make sure they are not another species, or God forbid, predators.

To find out how the neural wiring that allows for social behavior was created, postdoctoral researcher Dr. Anna Rita Nunes and research student Michael (Mikey) Glicksberg created a system designed to examine the effect of the hormone oxytocin, Known for enhancing social interactions, on the developing brain of zebrafish.They created engineered minnows whose nerve cells that produce oxytocin have a bacterial gene that encodes lethal sensitivity to antibiotics.By adding antibiotics to water, they could kill these neurons at different stages of fish development.

The researchers found that without oxytocin in the early stages of development – or rather, in the first two weeks of life – the stingrays evolved into adult fish with reduced social skills, ie those that do not swim in the flock. Re-emerged at a later stage of development, it was already too late.In other words, for adult fish to be able to swim in groups, oxytocin must wire the brain in a certain way at a critical time window for its development.

below Scientists have uncovered the mechanisms by which oxytocin wires the brain Open. They found that the neurons that produce oxytocin were essential for the formation of another type of neuron – the manufacturers of the neurotransmitter dopamine. As a result, in zebrafish brains that were not exposed to oxytocin in the first two weeks of life two different regions of the brain were characterized by a low amount of both dopamine producers and connections to these nerve cells.

One of these regions is responsible for processing Visual stimuli that are probably essential for identifying swimming partners. In mammalian brains, including humans, a parallel region is responsible for processing visual information in social situations. For example, this area controls the eye movements that scan the face of those in front of us to decipher an expression. In people with autism this scanning pattern often does not exist – evidence that their brain responds differently than usual to visually meaningful visual information. The second area where dopamine deficiency was parallel to an important neurotransmitter center in humans, involved in positive conditioning in social contexts. Social “- a group of brain regions that work together to process social information. In fish where the brain developed without oxytocin, the timing patterns of neural activity between these regions were completely different from the patterns in normal fish.

“Our study shows that oxytocin is much more than ‘love hormone’, the name “It plays a role in building neural systems that it uses later, including those involved in sensory information processing, cognitive processes, learning and reward,” says Glicksberg. “Oxytocin organizes the brain in a way that is essential for the conduct of social situations,” concludes Nunes.

, The changes that oxytocin produces in the fetal brain. Understanding these mechanisms may advance the study of the molecular causes of various developmental-neurological syndromes, including autistic continuum syndromes. Dr. Einat Wirzer and Dr. Jeanne Blechman from the Departments of Molecular Cell Biology and Molecular Neurobiology of the Weizmann Institute of Science; And Dr. Giovanni Petri of the Institute for Scientific Collaborations – ISI Foundation & ISI Global Science Foundation – in Turin, Italy.

More on the subject on the Scientist website:

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