From SciTechDaily:
To learn to socialize, zebrafish need to trust their gut. Gut microbes encourage specialized cells to prune back extra connections in brain circuits that control social behavior, new University of Oregon research in zebrafish shows. The pruning is essential for the development of normal social behavior.
The researchers also found that these ‘social’ neurons are similar in zebrafish and mice. That suggests the findings might translate between species — and could possibly point the way to treatments for a range of neurodevelopmental conditions. “This is a big step forward,” said University of Oregon neuroscientist Judith Eisen, who co-led the work with neuroscientist Philip Washbourne. “It also sheds light on things that are going on in larger, furrier animals.” The team reports their findings in two new papers, published in PLOS Biology and BMC Genomics.
While social behavior is a complex phenomenon involving many parts of the brain, Washbourne’s lab previously identified a set of neurons in the zebrafish brain that are required for one particular kind of social interaction. Normally, if two zebrafish see each other through a glass partition, they’ll approach each other and swim side by side. But zebrafish without these neurons don’t show interest. Here, the team found a pathway linking microbes in the gut to these neurons in the brain. In healthy fish, gut microbes spurred cells called microglia to prune back extra links between neurons.