Can the human brain grow neurons?

This is Mrs. Phlosphr and I was just in a debate with Mr. Phlosphr about whether or not the human brain can grow and/or strengthen neuronal pathways. I once took a Learning class in college with emphasis on biopsychology and the concept of neuronal growth was strongly evidenced in the studies we reviewed. I personally believe that the human brain can grow new neuronal pathways and strengthen existing pathways if given the right opportunity. For instance, if one were to take on a new task such as learning to play the piano. Neuronal pathways for piano playing would be weak, but with practice they would strengthen. This is an example among many. I just want to know what all you other Dopers think about this because Mr. Phlosphr disagrees with me. He believes the human brain is born with a certain number of these pathways and they remain constant throughout life. Please help me prove Mr. Phlosphr wrong!

I was told this during piano lessons as well. Not exactly. What I was told that the neural pathways to my middle fingers could be strengthened over a span of 90 days to the point that only a solitary finger could be made to wiggle as opposed to the mild wiggling of adjacent fingers by an untrained person. That said, I’m not sure if new neural pathways can be created. How would a nerve-ending sprout where non-exists ? What’s the mechanism and stimulus ?

You cannot grow new neurons although fetal cell research indicates its use might change this to some degree…I’m not sure how much though.

That said your brain has amazing capacity beyond what you actually use. You can most certainly strengthen or even re-route new neural pathways in the brain. As mentioned this is how you get better playing the piano through practice (or most anything through repetition). Doesn’t matter what age you are although young children seem to be able to form these pathways at breathtaking speed compared to adults (witness a 5 year old learning a new language in weeks compared to months for an adult).

Here is an extreme example of this and truly amazing:

Adults grow neurons too !
From Sigma Xi

Also this article in Nature: Long-term in vivo imaging of experience-dependent synaptic plasticity in adult cortex

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-The google cache of this article avoids Nature’s $25.00 article fee. There’s got to be a copyright infringement lawsuit in that somewhere.
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ye, i also read in scientific american that you CAN grow new brain cells. it used to be believed that you can’t, but you can. makes me feel better, cuz i like drugs you know :slight_smile:

Fernando Nottebohm discovered that brains do grow new neurons, but it took the scientific community thirty years to start taking him seriously.

Science advances quickly, but it has major issues admitting errors. It usually takes 10 years before a revolutionary idea moves from ridicule to acceptance. Hence Max Planck’s observation:

“A new scientific truth does not triumph by convincing its ppponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.”
and J.B.S. Haldane:
Theories have four stages of acceptance:
i) this is worthless nonsense;
ii) this is an interesting, but perverse, point of view;
iii) this is true, but quite unimportant;
iv) I always said so.

Hmm, the study I read recently said that the hippocampus created new cells, but the rest of the brain didn’t. (into adulthood that is)

That’s not a very good example. Our brains seem to be hard wired to some degree for language. If we learn a language at a very young age it is processed by one area of the brain. After a certain age (which I don’t remember the exact number) it becomes much more difficult to learn language because it is processed by a different area of the brain. This is also why someone taught a language at a very young age can speak it very easily, but someone who learns it at an older age will have great difficulty with phonetic sounds not in their own langauge (like a japanese person having difficulty with the english R sound).

Otherwise I agree with you. I used to design test equipment used in neurobiological research, and saw examples of many people who had suffered brain damage (one of the best ways to figure out how the brain works is to look at damaged ones and see what isn’t working). None were as severe as the exampleyou posted, but I did see that the brain’s ability to re-route and compensate for damage is truly amazing.

UH OK. So I’m wrong? I knew the brain could reroute neural pathwyas but making brand new ones - I thought - was not in our brains field of function. I may be wrong. I know it s postulated that Einstein used more than 30 percent of his brain, whereas normal ‘savages’ use more like 10 percent. One thing I do not understand is: if new neural pathways come with more learning, one would think by the time an adult human reaches say 70, they would be utilizing more of their brain then when they were an infant. So not 10% but more like 40%…I’ll look for a cite.

Well, this article doesn’t suggest that ‘neurons’ grow - it says that connections from and between neurons may grow, and that these connections have a role to play in cortical plasticity.

I always understood that neurons themselves cannot be built ‘online’, though 'tis the Nature of Science that the things we know are always about to change…!

Yes, but you need to bear in mind that quotes of this nature are a bag of steaming arse.

Bear in mind that as pathways are ‘created’, so they can die. The rate of creation and death needs to be considered.

Grrrrr. The 10% number is a myth. Some flake said it as a metaphor decades ago, and people think it actually means that 90% of your neurons are just sitting there doing nothing. You are using the whole brain.

The brain definitely both grows new neurons and strengthens old ones. I worked in brain research labs, BTW, and did my grad education in the field.

We were originally taught that you have 2 billion neurons by age 10, and that was it. This is so wrong. Now we know that there are 100 billion or more, and the brain has a major spurt of new growth and reorganization during adolescence, and during learning. I will post cites later when I have time. The hippocampus has stem cells that can grow new tissue. Other stem cells have just been discovered which can migrate to the brain and become neurons.

Yes. What we have here is a change in what we know about the extent to which individual neurons change and ‘grow’, not yet growth of new neurons. That gets us into semantic territory on the precise meaning of ‘growth’. However, the long standing view that adult neurons are mostly static, is taking a shellacking from these new EM studies.

I guess this is kinda a hijack, but what about the effects of alcohol on neurons and such? Does alcohol ‘kill’ brain cells?


It’s a rather technical news release, but here’s the gist:

4 females (2 adults, 2 children) got bone transplants from male donors. Unfortunately, these female patients died. The females’ brains were examined, and brain cells were found with Y (male) chromosome. Cells with male chromosomes could only have come from the bone transplant tissue. The brain cells must have grown after the transplant was done. This is evidence that adult brains do develop new cells.

“‘This study shows that some kind of cell in bone marrow, most likely a stem cell, has the capacity to enter the brain and form neurons,’ says Ẻva Mezey, M.D., Ph.D.”
"Most of the bone marrow-derived cells in the brain tissue were glia (support cells) and other non-neuronal cells. However, a small number of neurons from each brain also contained Y chromosomes, showing that those cells had developed from the transplanted male bone marrow. Most of these neurons were found in the cerebral cortex – the outer layer of the brain, which is responsible for conscious thought – and in the hippocampus, a region that helps with memory and other functions. "

Hope this helps the fight against ignorance a bit.

It’s a great question. Quick answer: yes. The whoe story is more complicated. Heavy drinking over a long time changes the brain. It visibly shrinks. I wish I had more time right now to go into detail, but some of the long term damage is due to free radicals and dehydration. Drink water and take vitamin B1 and C. Some say Acetyl-L-Cysteine helps, but I haven’t explored that. Don’t binge drink too much – it overwhelms your body’s ability to cope with toxins.


For 16 years, Roberta J. Pentney, Ph.D., professor of anatomy and cell biology at the University at Buffalo, has pondered these basic questions concerning chronic alcohol abuse and brain function. Cell morphometry – the quantitative study of the form and structure of cells – is her field, and her painstaking work with neurons in the cerebellum, the control center for movement, coordination and equilibrium, has yielded striking and unexpected answers:

Q. Does alcohol kill brain cells in adults?
A. Not in the cerebellum.

Q. What does happen?
A. Alcohol damages dendrites, reducing message traffic between neurons.

Q. Is the damage permanent?
A. No, it’s mostly reversible, but neuronal structure is changed in the process.

“For a long time, people were looking at cell loss as the real measure of alcohol’s effects,” she added. "What we’ve seen through this research is that you don’t have to lose entire neurons to disrupt brain function. All you need is damage, and we have developed a model for that kind of change with alcohol.

“The implications here are clear,” Pentney said. “The branching pattern in Purkinje neurons after recovery is not identical to that before recovery. You don’t end up with the same arrangement. There is a fair amount of recovery, but the neurons may not function in the same way. A different branching arrangement would result in a change in message transmission, which would change the way that particular part of the brain works”

My thoughts
Just because neurons are seen to be changed, does not necessarily mean that there is any measurable effect on your behavior or ability to think.

From another source:
*“Our findings, which are in vivo (in the living body), indicate that alcohol-induced brain damage occurs during intoxication.” *

The OP’s friend seems to be confusing two things (and followup posts haven’t made this clear): All brains of any animal make new neuronal connections all the time. Learning = making new connections. If it couldn’t make new connections, there would be no point of having a brain. For many years it was believed that human brains couldn’t make new neurons after birth. Recent evidence (some cited above) suggests otherwise, at least in some parts of the brain.

Not necessarily. For example, learning may be mediated via changes in synaptic efficiency, e.g. Dinse et al 1997 Adv Neurol 73: 159-178, taken from the end of their abstract:

(…) The short time scale of the effects and the aspect of reversibility support the hypothesis of fast modulations of synaptic efficiency without necessarily involving anatomic changes. Such systems of predominantly dynamically maintained cortical and adaptive processing networks may represent the neural basis for life-long adaptational sensory and perceptual capacities and for compensational reorganizations following injuries.

The paper deals with learning in rats BTW.
Learning could be mediated by any and all of the methods mentioned in this thread, i.e., growing new neurons, growing new connections between neurons, changing efficiency of synaptic junctions.

BTW, the Mezey et al paper mentioned by FranticMad is here

…but you may need a subscription to view the article. It does seem to be pretty convincing wrt the growth of new neurons.

I don’t think it does; there are simply a few different types of ‘growth’ that can occur!

Right you are. Cecil Adams on Do we really use only 10 percent of our brains? See also http://faculty.washington.edu/chudler/tenper.html