New study sheds light on how motor control develops

A study led by Stephanie Gaudreau, a Postdoctoral researcher at CHEO Research Institute and the University of Ottawa, who completed a PhD in biology and worked in Professor Tuan Bui’s lab investigates how young zebrafish fine-tune their movements as they grow. Their work, published across three peer-reviewed journals, traces the electrical changes inside nerve cells that help a wiggling larva transform into a coordinated swimmer.

The key players here are motoneurons: the cells that connect the nervous system to muscles and kickstart movement. As zebrafish mature, Bui’s team found, the electrical currents inside these motoneurons shift in distinct and predictable ways. It’s these shifts that seem to let the fish swap wild, jerky motions for smoother, more controlled ones.

“We show that the refinement of movement in growing zebrafish hinges on changes in ion currents that shape how motoneurons work,” explains Tuan Bui, Full Professor & Chair, Biology Department at uOttawa. “We identified that certain currents evolve in very particular ways during development, letting the motoneurons adjust as the animals get better at moving.”

Gaudreau spent years in Bui’s lab using a technique called electrophysiology to record the electrical activity of individual nerve cells in zebrafish at different ages. By timing their measurements to the fish’s developmental milestones, when the larvae started showing off new, more controlled moves, the team could link the changes in the electrical currents directly to improvements in movement. 

“These results came from experiments where we recorded individual ion currents from specific motoneurons in zebrafish as they developed,” Gaudreau says. “By mapping out these shifts, we could see how changes inside the nerve cells matched up with the fish getting better at swimming.”