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Medicine Science

Adult Human Brains Do Not Produce New Neurons, Study Suggests ( 76

Rich Haridy reports via New Atlas: New research from scientists at UC San Francisco is challenging half a century of conventional wisdom by suggesting the human brain may cease producing new neurons beyond childhood. While the divisive study may prove a blow to some research aimed at birthing new neurons to battle neurodegenerative disorders, it offers a new perspective on how the human brain can adapt in later life without such a capability. The team generated its data by studying brain specimens of 59 subjects, from babies to the elderly. The strategy was to look for the presence of young neurons or dividing cells by using certain antibodies that bind to those cells of interest. The focus was on the hippocampus region of the brain, known to be crucial for memory, and a comprehensively studied area previously suggested to be a key location for neurogenesis. The results were fairly comprehensive. Young or immature neurons were identified in plentiful volumes in prenatal and newborn samples but the rate consistently declined over childhood. The oldest sample that immature neurons were found in was 13 years of age, and adult samples displayed no evidence of new neurons. The study has been published in the journal Nature.

Adult Human Brains Do Not Produce New Neurons, Study Suggests

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  • by Anonymous Coward

    but adult neurogenesis has been demonstrated many times before:

    • by Anonymous Coward

      Not just that, but it makes literally no sense. Being able to recover from minor brain damage is essential to the functioning of any species with a well-developed brain. Brain damage happens from all sorts of things including starvation and severe sensory deprivation.

      Not being able to generate at least some new neurons would be a huge problem in an evolutionary standpoint. There's only so much you can do by just shuffling the connections around. At some point you need a sufficient number of neurons in the r

      • by Anonymous Coward

        Well, they did focus on just one region, and the brain has other regions ... So they kind of jumped to a conclusion there. All they showed was that using the technique they were using , they couldn't find new neurons in adults in that region ... Plenty more left to study

  • 50 Years? (Score:4, Interesting)

    by mentil ( 1748130 ) on Thursday March 08, 2018 @06:41AM (#56226339)

    Funny, 25 years ago I was told in school that the brain was the only part of the body that didn't produce new cells after birth. Only about 10, 15 years ago did I first hear that there was now good evidence that new neurons were produced after birth.

    • by Anonymous Coward

      Researchers have a hard remembering what they have said before.

    • Funny, 25 years ago I was told in school that the brain was the only part of the body that didn't produce new cells after birth.

      About 25 years ago, eggs were bad for you.

      Now they're good for you.

      In about 25 years, tobacco will be good for you . . .

      • They've already started on that.
        • by umghhh ( 965931 )
          My physician told me (this is already 3ya) that daily intake of small doses of nicotine seem to be associated with lesser chance of getting dementia. He advised me not to pick up smoking tho as it is better to have no brains than die of lung cancer. I wonder how it goes for e-cigs?
      • At least it's a longer and less obnoxious cycle than the bi-weekly coffee/chocolate good/bad flip-flopping...
      • by mysidia ( 191772 )

        Apparently that might have been wrong.... your brain COULD produce new cells after birth, but stop producing them some time before you reach adulthood.

        Perhaps continuing to produce neurons beyond childhood would cause some issues with how minds work.

        • by umghhh ( 965931 )
          If new neurons could cause you to question status quo, it may land you in reeducation camp. This is rather unhealthy.
      • by q_e_t ( 5104099 )
        Eggs killed Princess Di and caused house prices to fall!
    • Good old public school education huh...
      At birth for females they have a limited number of egg cells,

    • Re:50 Years? (Score:5, Interesting)

      by hey! ( 33014 ) on Thursday March 08, 2018 @09:21AM (#56226675) Homepage Journal

      That's the way science works. You keep gathering more evidence and as it mounts you sometimes have to change your mind. The eventual goal is to tackle complex questions.

      What makes a question complex? Evidence can be found for more than one possible answer. The world abounds in questions like that.

      If evidence in principle can force you to change your mind, then why keep collecting it once you've made up your mind? There's two good reasons. One is that once you've collected a lot of evidence, you don't have to change your mind every time a bit of contradictory evidence comes up, as long as the balance of evidence weighs in a certain direction. For example this study looked for new neurons and didn't find any. The news media's poor understanding of science means they jump to the conclusion that there aren't any new neurons. But at this point in the evidence gathering it's more likely they didn't do a good job of looking for them.

      The second reason is to learn to ask better questions. Thirty years ago we believed the brain was essentially static except for decay once you reached maturity. However at this point there is almost incontrovertible evidence that brain is far, far more plastic than we believed possible -- e.g. documented cases of epilepsy patients treated with a hemispherectomy regaining motor control of the affected body side. We assumed that this was because those patients grew new neurons, but if this finding holds up, we then have to ask: what is the mechanism of brain plasticity?

      Or it may be that this finding describes the usual case but in unusual ones the brain can rewire itself with new neurons. We don't know yet, but the point was until we looked we didn't understand well enough to know what we don't know.

    • Ya, that's what I was told in science & biology classes in the 1970's, you have what your born with. If an area gets damaged, another area attempts to take over. That's why at any one time there's such a low utilization percentage.
  • They just looked at the type of neurons in people's brains.
    Have they also scanned a persons brain over a period of time.
    Especially comparing scans of people who are learning new things to people who aren't.
    And looked if there are any changes to the neurons those people have?
  • Wrong. (Score:5, Informative)

    by Qbertino ( 265505 ) <> on Thursday March 08, 2018 @07:08AM (#56226393)

    The study found that certain indicators associated with the growth of cells in young mamals/people couldn't be found in grown-ups. This doesn't contradict the growth of cells in adult brains. The study isn't disputed as heavyly as the conclusions drawn are, but they are disputed.

    • Re:Wrong. (Score:5, Informative)

      by macklin01 ( 760841 ) on Thursday March 08, 2018 @10:53AM (#56227033) Homepage

      There's a big difference between growth of cells (they get bigger) and proliferation of cells (they divide to create new cells), and so it's important to be careful. (I've been working on modeling both cell growth and cell division for a good while, mostly in cancer and a little in tissue engineering and synthetic biology. e.g., here. [])

      I looked at the study. They stained for Ki-67, the gold standard immunohistochemical marker for cell division. Cells that are actively cycling--in late G1, S, G2, and M phase, and a smidgen of G1 phase after division because Ki67 protein doesn't instantaneously degrade--stain positive for this marker. In particular, it is a nuclear marker, so the stain is localized to the cell nucleus, and the stain is very definitive. It's one of the easiest immunostains to do image processing on, because you can do nuclear segmentation, then analyze the colors in the segmented nuclei to see if they stained positive or negative for Ki-67.

      And that Ki-67 marker was virtually non-existent in the region of interest in all the samples above 13 years old. See Figure 2 []. This is *the* universal gold standard marker for cell division used across pathology and experimental biology. So yes, the study indeed found no proliferating cells in the GCL. And then they used this "young neuronal cell" marker (DCX+PSA-NCAM+ cells) to further confirm what they already saw in Ki67.

      Also, the Nature link [] is the *summary* of the paper, and not the actual paper. It's pretty common for the big journals to ask for a non-involved scientist in the same field to write a summary and commentary when a potentially controversial or significant paper comes out. Here's the actual paper. []

  • by Anonymous Coward on Thursday March 08, 2018 @08:37AM (#56226579)

    For a long time, scientists believed that no new neurons are born in the brains of adults, meaning that when our existing brain cells become damaged or die, they are not replaced. However, it was later discovered that neurogenesis – meaning the creation of new neurons – does in fact in occur in the hippocampus, a brain region associated with memory. Unfortunately, the rate of neurogenesis is not always sufficient to replace all of our damaged neurons as we age, which is why many people suffer from dementia and other age-related cognitive deficiencies. Fortunately, a study conducted by the Beckley/Sant Pau Research Programme, and published in the journal Scientific Reports, reveals that certain compounds present in the psychedelic Amazonian brew ayahuasca actually stimulate the birth of new neurons.

    Researchers placed harmine and tetrahydroharmine – the most prevalent alkaloids in ayahuasca – in a petri dish with hippocampal stem cells, and found that this greatly increased the rate at which these cells developed into fully mature neurons. The results of this study were first presented at the Interdisciplinary Conference on Psychedelics Research in 2016, and represent the first evidence that components of ayahuasca have neurogenic properties, thereby opening up a wealth of possibilities for future research.

    We are currently conducting additional experiments to discern the magnitude of the observed effects, as well as undertaking studies on live animals. The replication of the present findings in vivo would represent a major breakthrough in mental healthcare, with potential applications ranging from treating neurodegenerative and psychiatric disorders to redressing brain damage associated with stroke or trauma.


    • Do you have any further data to support this? I got the impression that's a fun hippy drug like lsd

  • by Greyfox ( 87712 )
    How do they get cancer? Doesn't that require cell division?
  • Alright (Score:5, Interesting)

    by DontBeAMoran ( 4843879 ) on Thursday March 08, 2018 @10:33AM (#56226931)

    Childhood = build the internet
    Adulthood = route around damage, like the internet

  • Brain cells don't regenerate over the age of 25(ish).

  • The taxi driver series of studies needs explaining if this is true. (Taxi drivers exhibit a change in brain structure whilst acquiring The Knowledge, less intense professions show nothing, professions of similar intensity show similar gains. Because you can see before and after, it's possible to show the change taking place.)

    If you can only explain a subset of the data, you have explained nothing.

    Now, studies do indicate that 12 is an interesting year for the brain. The brain goes through various phases of

% "Every morning, I get up and look through the 'Forbes' list of the richest people in America. If I'm not there, I go to work" -- Robert Orben