Using a technique dubbed “brainbow,” the Virginia Tech Carilion Research Institute scientists tagged synaptic terminals with proteins that fluoresce different colors. The researchers thought one color, representing the single source of the many terminals, would dominate in the clusters. Instead, several different colors appeared together, intertwined but distinct. Credit: Virginia Tech

Neuroscientists know that some connections in the brain are pruned through neural development. Function gives rise to structure, according to the textbooks. But scientists at the Virginia Tech Carilion Research Institute have discovered that the textbooks might be wrong.

Their results were published today in Cell Reports.

“Retinal neurons associated with vision generate connections in the brain, and as the brain develops it strengthens and maintains some of those connections more than others. The disused connections are eliminated,” said Michael Fox, an associate professor at the Virginia Tech Carilion Research Institute who led the study. “We found that this activity-dependent pruning might not be as simple as we’d like to believe.”

Fox and his team of researchers used two different techniques to examine how cells – neurons that live in the retina and transmit visual information to the visual centers in the brain – develop in a mouse model.

“It’s widely accepted that from about 20 retinal converge onto cells in the lateral geniculate nucleus during development, but that number reduces to just one or two by the third week of a mouse’s life,” Fox said. “It was thought that the…

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