Brain scientists have filmed a first-of-a-kind birth video. It reveals specialized cells in the brains of mice dividing to create newborn nerve cells.
The images, published in the Feb. 9 Science, show intricacies of how certain parts of the adult mouse brain can churn out new nerve cells. These details may help lead to a deeper understanding of the role of this nerve cell renewal in such processes as memory.
Deep in the brains of mice, a memory-related structure called the hippocampus is known to be flush with new nerve cells. But because this buried neural real estate is hard to study, the circumstances of these births weren’t clear.
Using living mice, Sebastian Jessberger, a neuroscientist at the University of Zurich, and colleagues removed the outer layers of brain tissue that obscure the hippocampus. The scientists marked 63 cells called radial stem cells, which can divide to create new nerve cells. Researchers then watched these stem cells for up to two months, taking pictures every 12 or 24 hours.
During that time, 42 of these stem cells underwent a spurt of division, churning out two kinds of cells: intermediate cells that would go on to produce nerve cells as well as mature nerve cells themselves. Once this burst of activity ended, the radial stem cells disappeared by dividing themselves into mature nerve cells that could no longer split.
Many of these newly formed nerve cells had brief lives, dying either within the first four days, or 13 to 18 days after birth. It’s not clear what kills these newborn cells. Interspersed among the dying cells, survivors go on to knit themselves into the brain.
NERVE CELL PROGENY Over two months (days indicated by the numbers), two individual stem cells in an adult mouse’s hippocampus jump into action and produce offspring. The hippocampus is a brain area important to memory and navigation.