[LPisGood]

I once heard that this is an oft repeated myth, that neurons are not replaced throughout life.

It seems to me to that what you said is true, but for some odd reason I have a recollection of reading a debunking of this. Does anyone know what I might be thinking of?

[chewbacha]

They are just very very slow. It does happen but the turnover is not fast and certainly not every 7 years.

[mattkrause]

It’s been very hotly debated for ages.

At the moment, the consensus seems to be that some neurons[*] are occasionally born in adulthood (e.g., in the hippocampus), but there’s a lot less agreement on why or if this matters at all. It could be the remnants of a prenatal process or a neat method for providing “pointers” into memories.

* In the brain itself. It is widely agreed that olfactory sensory neurons turn over every month or two, but they almost have to because they’re exposed to all sorts of junk in the air and wouldn’t survive a lot longer anyway.