The new study relied on measures of neurogenesis that aren't always reliable when used on brain tissue taken from someone who has died, Gage says. And results from many labs, he says,'repeatedly confirm that neurogenesis can occur in the adult brain.' 'I feel confident in my lab's results,' Gage says in a written statement. One of those who questions the new study's conclusion is Rusty Gage, interim director of the Salk Institute in La Jolla, Calif., and one of the scientists whose research in the 1990s helped establish the idea that new cells do appear in the hippocampus of adult humans. 'I'm sure that there are going to be people who challenge ' says Alvarez-Buylla, a professor of neurological surgery at UCSF. The finding is bound to be controversial. It also calls into question claims that both exercise and some anti-depressant drugs could boost the production of new neurons in the hippocampus. The finding challenges decades of research suggesting that new neurons continue to appear in the hippocampus, an area of the brain involved in memory and emotion. 'In all of the adult samples we looked at, we couldn't find any evidence of a young neuron,' says Shawn Sorrells, the study's lead author and a senior researcher in the lab of Arturo Alvarez-Buylla at the University of California, San Francisco. The study of 59 samples from 29 brains of people of various ages found no immature neurons in anyone older than 13, scientists report online Wednesday in the journal Nature. Dendrites are green, dendritic spines are red and DNA is blue.Ī major study is challenging the widely held view that adult human brains make new neurons.

How many neurons in human brain