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Last week a paper came out saying no adult neurogenesis. But I see today this paper came out:

http://www.cell.com/cell-stem-cell/fulltext/S1934-5909(18)30...

It usually flips every month.

This is a critical comment that should be upvoted widely. The reason that this is such a difficult challenge is that the rate of adult hippocampal neurogenesis, even in rodents where everyone believes it happens, is on the order of between 1 neuron per minute and 1 neuron per hour. In a brain of 100 billion neurons, that's hard to detect.

The original SlateStarCodex post addresses this. He argues that a microscopic amount of neurogenesis that is too small to be responsible for the effects everyone cares about (depression, brain plasticity, etc.) should be rounded to zero.

It is entirely possible that the base-rate of neurogenesis in adult humans is very low, but in response to new stimuli (a new exercise regimen, for example) responds by generating neurons..Perhaps I am missing the information in one of the supplemental pages, but I do not see info on history of exercise or anti-depressant use in the Nature paper.

A response to the Cell article from the team from the article that did not find neurogenesis.

""" In an email statement, that group, which works out of developmental neuroscientist Arturo Alvarez-Buylla’s lab, said that while they found the new study’s evidence of declining blood vessel growth in the adult hippocampus interesting, they are not convinced that Boldrini and her colleagues found conclusive evidence of adult neurogenesis.

"Based on the representative images they present, the cells they call new neurons in the adult hippocampus are very different in shape and appearance from what would be considered a young neuron in other species, or what we have observed in humans in young children," they wrote. """

Much more at the original article. TL;DR: They think this probably doesn't meaningfully change things from their own findings.

http://www.latimes.com/science/sciencenow/la-sci-sn-new-brai...

They're confusing something else with neurogenesis.

Probably. But to clarify you think something besides immature GNs in the granular zone expresses DCX and PSA-NCAM but not NeuN?

I have my idea; I just want to hear yours.

Why don't you go for it? I'd like to hear.

glial cells moonlighting, by expressing the molecular marker signature of young neurons.

And in terms of papers like Spalding et al., 2013 which "assessed the generation of hippocampal cells in humans by measuring the concentration of nuclear-bomb-test-derived 14C in genomic DNA"? https://www.sciencedirect.com/science/article/pii/S009286741...

The original study https://www.nature.com/articles/nature25975 that prompted the SSC article has an interesting discussion of this result in their supplement:

"A study using 14C birthdating on sorted NeuN+ nuclei suggested that hundreds of new neurons are generated per day in the adult human hippocampus, with little decline with age. The results obtained from this method differ from the data presented here and other histology studies that show a sharp decline in markers of newly formed neurons during early postnatal development. Birthdating with 14C relies on the isolation of neuronal nuclei using NeuN antibodies, but subpopulations of oligodendrocytes and microglia can also express NeuN. 14C could also possibly become incorporated into DNA through methylation or DNA repair independent of cell division, processes that have been shown to occur at higher rates in the hippocampus. The proposed addition of new neurons to the adult caudate nucleus using this method is not supported by other work in the human or BrdU labeling in adult macaques. The 14C method is an innovative approach to perform birthdating in postmortem human samples, but it has not been validated in animal studies."

In the cortex at least there have been reports of DCX+ NCAM+ cells that are arrested in an immature state, meaning they are not necessarily newly generated, just stuck in "standby" mode.

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