Follow the current
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.”
“We show that the refinement of movement in growing zebrafish hinges on changes in ion currents that shape how motoneurons work”
Tuan Bui
— Full Professor & Chair, Biology Department at uOttawa
From fish to humans: Understanding how movement develops
In their first few days of life, zebrafish quickly learn to move in new and more coordinated ways. Their early, rapid movements are gradually joined by slower, smoother swimming as new motor neurons develop. Researchers found that changes in specific electrical currents within these nerve cells help shape this transition, offering new insight into how the nervous system develops the ability to control movement.
“Because so many neural mechanisms are shared across species, our work could help explain how humans get better at moving after birth,” Professor Bui concludes. “It may even help us pinpoint which ion currents are most important for movement and how they do their job.”
The study, Developmental Changes to the M-Current Shape the Direction of Its Neuromodulation in Zebrafish Motoneurons, was published in the Journal of Neuroscience in August 2026. DOI: https://doi.org/10.1523/JNEUROSCI.0420-26.2026 /
Authorship: Stephanie F. Gaudreau, Tuan V. Bui