# fact check - cells multiplying in the brain? **URL:** \ **Category:** Factual Questions\ **Created:** [November 27, 2013, 2:27am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878 "2013-11-27T02:27:10Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![HazelNutCoffee](https://avatars.discourse-cdn.com/v4/letter/h/ac91a4/32.png) [@HazelNutCoffee](https://boards.straightdope.com/u/HazelNutCoffee)\ **Post date:** [November 27, 2013, 2:27am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/1 "2013-11-27T02:27:10Z")
I am reading a friend’s manuscript. This person asserts that whenever a person repeatedly thinks of something, the image is imprinted on to a brain cell at a rate of 50,000 cells a second (by powers of 2, so 2, 4, 8, 16, 32, etc). This person uses the phrase “the brain cells multiply by 2” whenever we think of something. My gut tells me that this is not correct, but my understanding of how the brain works is pretty limited, so maybe I’m the one who’s misinformed. Is my friend correct in what he’s saying? If he’s not, does anyone have any idea what he’s actually trying to say? Thanks. 🙂 ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [November 27, 2013, 2:55am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/2 "2013-11-27T02:55:20Z")
We really don’t know the answer to the question, but it’s almost certainly unrelated to brain cells reproducing. Anyone who could provide a definitive answer about how skills and memories are stored would be looking at a Nobel or two. I think it’s still the leading theory that rehearsal (of information, memories, physical activity, etc.) strengthens the synapse connections between neurons, or creates more connections between the neurons involved. It’s often described like wagon-wheel ruts forming in roads that are used often, while unused roads are slowly reclaimed by weeds and trees. The brain is much more about interconnections of cells than numbers of cells, which is part of why that old adage about using only 10% of the brain is so totally incorrect. ---
**Author:** ![HazelNutCoffee](https://avatars.discourse-cdn.com/v4/letter/h/ac91a4/32.png) [@HazelNutCoffee](https://boards.straightdope.com/u/HazelNutCoffee)\ **Post date:** [November 27, 2013, 3:09am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/3 "2013-11-27T03:09:02Z")
I guess the part that I was most skeptical about is the idea that our brain cells multiply by two when we think about something repeatedly. Wouldn’t we then end up with an infinite number of cells? Or do they die at the same rate? And also the the precise rate of imprinting happening at “50,000 cells a second”. I couldn’t find a cite for that number anywhere. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [November 27, 2013, 3:44am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/4 "2013-11-27T03:44:45Z")
The only brain areas that would be relevant is in the hippocampus, which does memory functions like consolidation (short term --\> long term). I am unaware of any number associated with this but am skeptical of the stated number. The splitting of cells into two, then four, etc. is associated with mitosis, but neurons are much more structurally complex and don’t “clone.” AFAIK. With the other brain areas, and including the hippocampus, is dendritic arborization - the neurons form new connections to other neurons, strengthening associations, and lose connections to irrelevant neurons. The only other areas aren’t relevant - the olfactory system and (I think?) the gustatory (taste) system. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [November 27, 2013, 5:15am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/5 "2013-11-27T05:15:00Z")
If you have reported what your friend wrote anything like correctly, it is very ,very wrong. Thinking about something, or laying down a memory of something, does not involve any multiplication of brain cells, probably not at all, certainly not to a significant degree, and absolutely certainly not at tremendous rates. He may have been thinking of synapses (points where brain cells connect and communicate with one another), or possibly changes in the axonic or dendritic branches (roughly speaking, output and input regions, respectively, of the cells). Memory formation may (I say “may” because we don’t really know) involve some new growth of these (synapses and/or axonic or dendritic branches), but even so, his numbers are nonsense and there is no repeated doubling process involved. Indeed, most likely the main thing that is going on when memories are formed is not so much the formation of new synapses, etc., but the strengthening of the connections at some pre-existing ones, and the relative weakening of those at others. The truth is that neither the neural basis of thought nor that of memory formation is very well understood, as yet, but we certainly know enough to be able to say that what you say your friend says is not in touch with the reality. Frankly, it sounds to me more like schizophrenic ravings than science (even taking into account the possibility that you may have garbled it a bit), but perhaps it is merely rather ill-informed and incompetent bullshitting. ---
**Author:** ![DataX](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@DataX](https://boards.straightdope.com/u/DataX)\ **Post date:** [November 27, 2013, 5:18am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/6 "2013-11-27T05:18:40Z")
I hope this is a fiction manuscript - none of that makes a lick of sense and I struggle to think where he would have gotten any of that nonsense. Oh wait - I think this is it > [@](#): > > When studying human physiology generally and the brain in particular, it is essential to keep in mind that development and aging are a continuum. From the moment you are born, you begin to age. So, too, your brain does not simply “develop” in the first part of your life and “age” in the last part of your life. While your brain was forming in the embryo, it was developing nerve cells at the rate of about 50,000 per second. Think of that explosive development,–50,000 per second. But before you were born did you know that you had already lost at least 50% percent of those cells? Most are concerned about losing nerve cells at the other end of the life cycle when, in reality, you lost more nerve cells before you entered the world. [http://education.jhu.edu/PD/newhorizons/Neurosciences/articles/Successful%20Aging/](http://education.jhu.edu/PD/newhorizons/Neurosciences/articles/Successful%20Aging/) And you know how embryos are built - one cell - which divides - then two cells - and so on. Closest thing I can think of. For a fully built human brain - doesn’t make any sense. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [November 27, 2013, 6:07am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/7 "2013-11-27T06:07:19Z")
Make sure that the manuscript includes the part where we use 10% of our brain . 🙂 Human development follows the pattern of “makes lots of neurons, then kill a bunch off later.” This naturally happens throughout the teenage years. After that, you should not lose or gain neurons to any degree except in those certain areas. Also, beer doesn’t really kill your brain cells, at least directly, drink up! ---
**Author:** ![Max\_the\_Immortal](https://avatars.discourse-cdn.com/v4/letter/m/6de8d8/32.png) [@Max\_the\_Immortal](https://boards.straightdope.com/u/Max_the_Immortal)\ **Post date:** [November 27, 2013, 6:40am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/8 "2013-11-27T06:40:56Z")
As a rule, mature neurons do not divide. What appears to matter is the connections between neurons. In rough terms, a neuron at rest is charged at, let’s say, -70mV. Incoming signals from other neurons can be summarized as “+2mV”, “-1mV”, “+3mV”, “-3mV”, “-2mV”, and so on, altering the charge of the receiving neuron, though the intensity decays over time and space. If the incoming signals make the part of the cell called the axon hillock reach, say, -55mV, this unleashes a cascade called an action potential, which travels along the neuron’s axon (outing signal cable) and ultimately sending its own “+2mV” etc. signals to other neurons. The nature of the signal (-3mV or +1mV or whatever) is determined at the synapse; the connection between the neurons. This action potential totally depolarizes the cell; once it reaches -55mV the cascade is a runaway process and the membrane potential will even be positive briefly, and then plunge down again to, say, -75mV before it recovers to its resting state of -70mV. This takes maybe a few milliseconds. If an incoming signal reaches a neuron during this brief period of depolarization, the neuron reacts differently to it, and the signal at that synapse is strengthened; a “-2mV” synapse could become a “-3mV” synapse. This is called long-term potentiation, or LTP. This process isn’t necessarily learning per se, but giving someone a drug that inhibits LTP will prevent them from learning until the drug wears off. ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [November 27, 2013, 6:44am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/9 "2013-11-27T06:44:54Z")
> [@thelurkinghorror](#): > > Also, beer doesn’t really kill your brain cells, at least directly, drink up! Cite? Not that I’m doubting you; I want oh so fervently for it to be true. I just want to know more about the subject. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [November 27, 2013, 7:22am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/10 "2013-11-27T07:22:36Z")
> [@Washoe](#): > > Cite? Not that I’m doubting you; I want oh so fervently for it to be true. I just want to know more about the subject. [Cracked](http://www.cracked.com/article_19370_the-6-most-frequently-quoted-brain-facts-that-are-total-bs.html). [NYT article, with references to studies](http://www.nytimes.com/2004/11/23/health/23real.html?_r=3). After reading, I think you earned yourself another! ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [November 27, 2013, 7:34am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/11 "2013-11-27T07:34:12Z")
> [@njtt](#): > > Thinking about something, or laying down a memory of something, does not involve any multiplication of brain cells, probably not at all, certainly not to a significant degree, and absolutely certainly not at tremendous rates. It turns out that’s not entirely correct. [Neurogenesis](http://en.wikipedia.org/wiki/Neurogenesis) does occur in a couple places, including the dentate gyrus (part of the hippocampus) which is involved in memory and learning. Not too long back I saw a report that the neurogenesis in this region happens only when novel events are remembered. It’s possible that this contributed to the misinformation in the OP friend’s manuscript. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [November 27, 2013, 7:57am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/12 "2013-11-27T07:57:27Z")
We have long term memories (semi-permanent, but we have to access them first) and short term memory, blink and it’s gone (and others, like working memory, which is identical to or distinct from STM, depending on who you ask, iconic memory, etc.). In order to hold onto anything for more than a short time, it needs to be sent to long term memory. Rehearsal is one way to do this (“what was her number? 867-5309… 867-5309… 867-39… shit!”). The hippocampus and surrounding areas (medial temporal lobe) is active when you do that, using the long term potentiation mention above. Damage to certain parts of the hippocampus can make new memories difficult to form, but it doesn’t affect already learned things. STM and LTM don’t really have specific brain areas associated, but sensory memories will be close, e.g. visual memories will incorporate the occipital lobe. ---
**Author:** ![HazelNutCoffee](https://avatars.discourse-cdn.com/v4/letter/h/ac91a4/32.png) [@HazelNutCoffee](https://boards.straightdope.com/u/HazelNutCoffee)\ **Post date:** [November 27, 2013, 11:15am UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/13 "2013-11-27T11:15:11Z")
Thanks everyone. I swear I haven’t garbled anything - I’m quoting the manuscript directly for the most part. I shall let my friend gently know that this information is not accurate. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [November 27, 2013, 6:05pm UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/14 "2013-11-27T18:05:28Z")
Here’s another way to look at it: If there really is exponential doubling that gets you 50,000 cells in one second of thought, then a 1-hour classroom experience produces 50,000\*2^3600 cells. That’s more than the number of atoms in the universe. ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [November 27, 2013, 6:54pm UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/15 "2013-11-27T18:54:33Z")
> [@dracoi](#): > > Here’s another way to look at it: If there really is exponential doubling that gets you 50,000 cells in one second of thought, then a 1-hour classroom experience produces 50,000\*2^3600 cells. You mean it even works when you’re comatose? :eek: ---
**Author:** ![Yllaria](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yllaria/32/3452_2.png) [@Yllaria](https://boards.straightdope.com/u/Yllaria)\ **Post date:** [November 27, 2013, 9:29pm UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/16 "2013-11-27T21:29:18Z")
If he wants to read up on it, I’d recommend In Search of Memory: The Emergence of a New Science of Mind by Eric R. Kandel. If only to have your friend wade through phrases like: “intracellularly recorded action potential”. If you want to make it easier, from a relevant figure in the book: “Short term: A single stimulus strengthens the synapse. Long term: Repeated stimulation causes kinases to move into the nucleus, leading to gene expression and growth of new synapses.” So, yes, repetition creates/reinforces memory. No, it doesn’t make new cells. As **njtt** said, repetition can cause growth of new synapses. But there is no doubling of anything, especially no redoubling with additional repetitions. ---
**Author:** ![DataX](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@DataX](https://boards.straightdope.com/u/DataX)\ **Post date:** [November 27, 2013, 9:45pm UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/17 "2013-11-27T21:45:07Z")
> [@Yllaria](#): > > If he wants to read up on it, I’d recommend In Search of Memory: The Emergence of a New Science of Mind by Eric R. Kandel. If only to have your friend wade through phrases like: “intracellularly recorded action potential”. > > If you want to make it easier, from a relevant figure in the book: > > “Short term: A single stimulus strengthens the synapse. > Long term: Repeated stimulation causes kinases to move into the nucleus, leading to gene expression and growth of new synapses.” > > So, yes, repetition creates/reinforces memory. No, it doesn’t make new cells. As **njtt** said, repetition can cause growth of new synapses. But there is no doubling of anything, especially no redoubling with additional repetitions. Obviously this guy (the friend) doesn’t understand the brain, but I’m pretty sure the link I posted in my prior post is the source (somehow) of his delusions. 1. That figure of 50,000 cells per second is a widely quoted number on how many cells are produced during fetal development. My own math came up with 5,000 -10,000 - if you take the TOTAL number of brain cells and divide it by the number of seconds in 9 months. 2. The doubling of cells makes no sense in an adult brain, but an embryo DOES start out as one cell - then splits in 2 giving 2, 4, 8, 16 … I thought at some point it stopped dividing equally, but in the beginning - this is what happens. It is the only biological thing I can think of that would involve EXACT doubling of cells. The combination of the 50,000 being a number cited for how fast the brain grows in the womb - ALONG WITH - the doubling of the number of cells in fetal (at least very early on) development leads me to believe something like the link I posted is the source for at least part of his belief. Obviously he hot everything wrong, but I would bet at least two dollars that is where he is getting those numbers from. As far as the imprinting thoughts - and repeated thing - that beats me - but I could see him twisting something like you posted into such a theory. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [November 27, 2013, 10:19pm UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/18 "2013-11-27T22:19:39Z")
> [@dtilque](#): > > It turns out that’s not entirely correct. [Neurogenesis](http://en.wikipedia.org/wiki/Neurogenesis) does occur in a couple places, including the dentate gyrus (part of the hippocampus) which is involved in memory and learning. Not too long back I saw a report that the neurogenesis in this region happens only when novel events are remembered. The fact that neurogenesis occurs to some degree in parts of the brain “involved in memory and learning” (actually that would be pretty much all the brain), is not itself evidence that neurogenesis is involved in the process of memory and learning. It almost certainly isn’t in any relevant way. I am aware of neurogenesis and considered mentioning it in my original post, but decided against it on the grounds that it would be more misleading than helpful to bring it up. As to your last claim, i would like to see the cite, as what you are implying seems _very_ unlikely to me. Laying down a memory can, and normally does, happen very rapidly. Neurogenesis, especially the growing of a new cell to the point of size and morphological complexity where it can do anything cognitively useful, is bound to be a much slower process. I find it pretty much unimaginable that neurogenesis plays any role in the formation of particular memories, although it may play a role in preparing the brain for further learning of a particular sort, or something like that. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [November 27, 2013, 10:22pm UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/19 "2013-11-27T22:22:30Z")
> [@HazelNutCoffee](#): > > Thanks everyone. I swear I haven’t garbled anything - I’m quoting the manuscript directly for the most part. I shall let my friend gently know that this information is not accurate. “Not accurate” is putting it kind of mildly! ---
**Author:** ![Yllaria](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yllaria/32/3452_2.png) [@Yllaria](https://boards.straightdope.com/u/Yllaria)\ **Post date:** [November 27, 2013, 10:44pm UTC](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878/20 "2013-11-27T22:44:04Z")
> [@DataX](#): > > Obviously this guy (the friend) doesn’t understand the brain, but I’m pretty sure the link I posted in my prior post is the source (somehow) of his delusions . . . . That sounds perfectly plausible. No argument. The book is largely autobiographical and gives what looks like a good history of memory research. In case the friend argues with “um, no” or actually wants background. [Next page](https://boards.straightdope.com/t/fact-check-cells-multiplying-in-the-brain/674878.md?page=2)