Our brains carry shadowy imprints of our bodies within them, ghostly collections of neurons whose organization reflects the body areas to which they connect. Scientists think that these imprints, known as topographic maps, make it more efficient for our brains to process incoming sensory information and coordinate outgoing motor commands.
These maps form early in our development. But how do they form? How do we ensure that a nerve that helps us speak finds its way to the throat instead of, say, a finger? Working with zebrafish, Dr. Cecilia Moens, a developmental biologist at Fred Hutchinson Cancer Research Center, recently discovered that time is key in shaping the topographic map that represents the muscles of the throat.
Now, in follow-up work published April 16 in the journal Developmental Cell, Moens and her team reveal the molecular cue that controls when the molecular beacons that guide neurons appear. The scientists found that a vitamin A derivative called retinoic acid orchestrates the appearance of these beacons on both sides: in the brain region where the neurons’ cell bodies are, and in the body region into which their long axons stretch.
That coordinated regulation “was completely unexpected to us,” Moens said.
A deeper understanding of how the body develops and maintains this map could help scientists working to repair a dysfunctional or damaged vagus nerve, which can affect speech and swallowing. And, Moens noted, because cancer cells often resurrect early developmental pathways to sustain their growth and spread, the work could give important insights to cancer researchers.
