Register for an account

X

Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.

X

Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

Mind

Brand New Cortical Neurons

Neuroskeptic iconNeuroskepticBy NeuroskepticOctober 5, 2010 9:49 PM

Newsletter

Sign up for our email newsletter for the latest science news

Are new neurons created in the adult brain?

placeholder

For a long time, everyone thought the answer was "no". Then, about 15 years ago, we learned that neurogenesis does occur in the adult brain, but it was thought to be limited to two very small regions, the dentate gyrus and the sub-ventricular zone. Except in cases of injury, when adult neurogenesis had been reported elsewhere.

Now Guo et al look set to overturn this orthodoxy in a new Journal of Neuroscience paper, as they found ongoing neurogenesis in healthy adult brains in an area called the piriform cortex, part of the cerebral cortex.

The key to the discovery was oligodendrocyte progenitor cells (OPCs). OPCs were previously believed to only be able to turn into cells called oligodendrocytes, which are not neurons, but glia; glia are a kind of support crew for the brain.

But Guo et al show convincingly (with the help of genetically modified mice) that OPCs do become neurons in the piriform cortex of adult mice. Once they've been "born", these new neurons mature into functional pyramidal cells - they form synapses with other neurons, and otherwise seem to be perfectly happy, and they survived for hundreds of days (i.e. most of a mouse's lifetime).

The methods they used are complex but the crucial result was that they observed pyramidal cells expression yellow fluorescent protein, in mice genetically modified to express this protein only in OPCs; the picture above this post is one of these "yellow" (I know, it looks green to me) neurons.

This isn't the first paper to report neurogenesis in the adult mouse piriform cortex - a different group did so in 2008, but then two other experiments published later that year failed to confirm the result, so it's remained controversial. Whether this will end the controversy is uncertain but it looks pretty solid to me.

What does it all mean? The piriform cortex is a bit of a weird area, as while it's part of the cerebral cortex, the most "complex" part of the brain, it is evolutionary very old, and quite unlike the neocortex which is by far the largest part of the brain in humans.

The piriform is involved in the sense of smell, which is very important for mice, not so much in humans. We do have a piriform cortex, but it's tiny. Whether adult neurogenesis also occurs in the neocortex is the next big question...

rb2_large_white.png

Guo F, Maeda Y, Ma J, Xu J, Horiuchi M, Miers L, Vaccarino F, & Pleasure D (2010). Pyramidal neurons are generated from oligodendroglial progenitor cells in adult piriform cortex. The Journal of neuroscience : the official journal of the Society for Neuroscience, 30 (36), 12036-49 PMID: 20826667

    2 Free Articles Left

    Want it all? Get unlimited access when you subscribe.

    Subscribe

    Already a subscriber? Register or Log In

    Want unlimited access?

    Subscribe today and save 70%

    Subscribe

    Already a subscriber? Register or Log In