# "learning involves neural path formation" - how do we know? can this be measured? **URL:** \ **Category:** Factual Questions\ **Created:** [June 16, 2010, 10:52pm UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481 "2010-06-16T22:52:57Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![code\_grey](https://avatars.discourse-cdn.com/v4/letter/c/f4b2a3/32.png) [@code\_grey](https://boards.straightdope.com/u/code_grey)\ **Post date:** [June 16, 2010, 10:52pm UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/1 "2010-06-16T22:52:57Z")
I encounter variants of this phrase pretty commonly, and it seems used completely mindlessly. “Lack of sleep prevents neural path formation” or maybe “use of essential vitamins strengthens the Flying Spaghetti Monster’s beneficial effect on memory”. Well, so what do we actually empirically know about the neurobiology of learning? Can we somehow observe or even directly influence these alleged paths? Note that I am not trying to argue against basic empirical observations like “if you do some learning, you learn, and if you don’t, you don’t”. But how do we know that this happens because of the neural pathways and not because of the more streamlined flow of chi along the mystic meridian or some other such purely speculative mechanism? ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [June 16, 2010, 11:21pm UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/2 "2010-06-16T23:21:59Z")
[Long-term potentiation](http://en.wikipedia.org/wiki/Long-term_potentiation) might be a good place to start. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [June 16, 2010, 11:31pm UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/3 "2010-06-16T23:31:47Z")
[Eric Kandel](http://en.wikipedia.org/wiki/Eric_Kandel) ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 17, 2010, 3:24am UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/4 "2010-06-17T03:24:48Z")
Thing is once you get into organisms significantly more complex than _Aplysia_ it becomes hard to have a non-learning control group. Two groups of rats. One pair a buzzer with a shock and learns to avoid the shock by jumping onto a platform. We attempt to keep the learning to avoid the shock as the only variable so another group gets a the same number of shocks to the same number of buzzes but gets them whether or not they’ve jumped on the platform. Did the second group not learn? Nope, they learned too. They learned helplessness; that no matter what they did they would get a shock. Back in my undergraduate days I worked in the lab of a psychologist whose position was that we could more precisely determine what were the differential effects of experience and that those at least made for a good list of likely suspects for the substrate of learning. That research clearly demonstrated changes at the level of the individual synapses (the connections between neurons), in the number of synapses and the types of synapses, the amount of dendritic branching in neurons in various parts of the brain, and of the sorts of supporting cells. Sometimes experience caused increases of various sorts but sometimes learning caused connections to be pruned as well. ---
**Author:** ![code\_grey](https://avatars.discourse-cdn.com/v4/letter/c/f4b2a3/32.png) [@code\_grey](https://boards.straightdope.com/u/code_grey)\ **Post date:** [June 18, 2010, 3:58am UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/5 "2010-06-18T03:58:47Z")
> [@DSeid](#): > > Back in my undergraduate days I worked in the lab of a psychologist whose position was that we could more precisely determine what were the differential effects of experience and that those at least made for a good list of likely suspects for the substrate of learning. That research clearly demonstrated changes at the level of the individual synapses (the connections between neurons), in the number of synapses and the types of synapses, the amount of dendritic branching in neurons in various parts of the brain, and of the sorts of supporting cells. Sometimes experience caused increases of various sorts but sometimes learning caused connections to be pruned as well. could you please be more specific here? What organism was that? How did you go about examining the synapses to reach these conclusions? How expensive and hard/easy to replicate is this type of research? ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 18, 2010, 4:51am UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/6 "2010-06-18T04:51:25Z")
Mostly rats but also occasional monkey research. Techniques varied from quantifying the degree of dendritic branching of certain cells in certain regions of the brain stained with a method that made such counting possible (Golgi prep) to examination of the synapses under an electron microscope, both counting number and measuring the sorts of synaptic densities within the individual synapses. [Here’s](http://www.jstor.org/pss/1130197) an abstract and a first page of an article to introduce the ideas, and a [taste](http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6SYR-483SSKY-22W&_user=10&_coverDate=03%2F11%2F1985&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1373483197&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=e0f614338728b8308fa28cf379b583f8) of [some fairly well done](http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7MD6-4DJ4R3X-JH&_user=10&_coverDate=09%2F30%2F1985&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1373483374&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=8d6d50cd69a0e9715b3926636cdd523f) studies from that time. ---
**Author:** ![code\_grey](https://avatars.discourse-cdn.com/v4/letter/c/f4b2a3/32.png) [@code\_grey](https://boards.straightdope.com/u/code_grey)\ **Post date:** [June 18, 2010, 2:42pm UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/7 "2010-06-18T14:42:18Z")
**DSeid** , how do those procedures work mechanically? Is it something like MRI, completely non-destructive? Or do you make a hole in rat’s skull to extract some brain tissue? Or do you kill the rat and then make the hole? If the rat survives, how many times can you run different experiments or maybe a single long multi-stage experiment on the same rat? ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 18, 2010, 4:03pm UTC](https://boards.straightdope.com/t/learning-involves-neural-path-formation-how-do-we-know-can-this-be-measured/543481/8 "2010-06-18T16:03:43Z")
Kill the rat and immediately process the brain, staining it, embedding it in resin, and then slicing it very thinly. Apparently there are now [commercial services](http://www.neurostructural.org/pdf/services.PDF) that will do that grunt work. (PDF but with some decent pictures.)