Scientists have for the first time identified why in many people with autism and other neurodevelopmental disorders, different parts of the brain don't talk to each other very well.
Laboratory (EMBL) in Monterotondo, Italy, and collaborators at the Istituto Italiano di Tecnologia (IIT), in Rovereto, and La Sapienza University in Rome, demonstrated that it can be caused by cells called microglia failing to trim connections between neurons.
"We show that a deficit in microglia during development can have widespread and long-lasting effects on brain wiring and behaviour," lead researchers Cornelius Gross, said. "It leads to weak brain connectivity, decreased social behaviour, and increased repetitive behaviour, all hallmarks of autism."
The findings indicate that, by trimming surplus connections in the developing brain, microglia allow the remaining links to grow stronger, like high-speed fibre-optic cables carrying strong signals between brain regions.
But if these cells fail to do their job at that crucial stage of development, those brain regions are left with a weaker communication network, which in turn has lifelong effects on behaviour.
The researchers found that mice with fewer microglia had weaker connections between neurons, and less cross-talk between different brain regions.
More From This Section
When Rosa Paolicelli, a PhD student in Gross' lab, studied the mice's behaviour, she discovered that mice with fewer microglia and decreased connectivity displayed behaviours commonly associated with autism spectrum disorders.
These mice spent more time repeatedly grooming themselves, and avoided social interactions.
The study was published in journal Nature Neuroscience.