This animation tracks how the human brain develops over nine months of gestation.

The human brain grows enormously during gestation, both in terms of its size and its number of neurons. As shown in the animation, the nervous system contains relatively small numbers of cells during the first months of gestation. As the fetus develops, billions of neurons are added to create a more complex brain. More neurons can still be added even in adulthood.

This animation is a clip from a 2008 Holiday Lecture Series, Making Your Mind: Molecules, Motion, and Memory. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different steps in the developmental process.