The activation of young brain cells in adult mice is necessary not just for forming memories, but consolidating them during rapid eye movement sleep, a study shows.

Adult neurogenesis, already appreciated for its role in learning and memory, also participates in mental health and possibly even attention, new research suggests.

Conflicting results on the existence of new neurons in adults have researchers designing new ways to identify and count neuronal progenitors—and finally get to the bottom of neurogenesis.

Despite doubts last year about human adult neurogenesis, a study shows even 80-year-olds develop new cells in the hippocampus, but such growth is diminished in patients with Alzheimer’s disease.