tag:blogger.com,1999:blog-18103977.post6786080628602473235..comments2024-03-28T03:24:52.114-04:00Comments on The Lansey Brothers' Blog: You Brain Is Like A Lump of CoalEli Lanseyhttp://www.blogger.com/profile/01955234977479398457noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-18103977.post-988676268500365892009-09-20T23:55:05.695-04:002009-09-20T23:55:05.695-04:00Eli's approximation assumes one direct connect...Eli's approximation assumes one direct connection from each neuron to each other neuron, no matter how far apart those two are in the brain. And he was off by a factor of 10^50. <br /><br />Adding a scaling factor at the front of that won't come near making the statement true.notElonhttps://www.blogger.com/profile/04857651031212875523noreply@blogger.comtag:blogger.com,1999:blog-18103977.post-22687718114466187152009-09-13T10:58:38.028-04:002009-09-13T10:58:38.028-04:00I don't know how this impacts y'all's ...I don't know how this impacts y'all's math (and don't feel like calculating how), but two neurons can be connected with two or more connections - Neuron A can have multiple synapses with Neuron B.Michael Kopinskyhttps://www.blogger.com/profile/16239953045100689630noreply@blogger.comtag:blogger.com,1999:blog-18103977.post-82973901548649167432009-09-10T18:55:48.148-04:002009-09-10T18:55:48.148-04:00That could explain lumpy :)That could explain lumpy :)jrshmuelnoreply@blogger.comtag:blogger.com,1999:blog-18103977.post-40786317963285110412009-09-09T15:14:41.505-04:002009-09-09T15:14:41.505-04:00To formalize what notElon pointed out, for N objec...To formalize what notElon pointed out, for N objects there are N(N-1)/2 possible connections between them, if we allow them to be fully interconnected. See <a href="http://en.wikipedia.org/wiki/Triangular_number" rel="nofollow">Triangle number</a>. For a large N, this is approximately N^2/2.<br />So, for your carbon example, where N~7x10^25, the number of possible connections is around 2.5x10^51. However, the number of atoms in the universe is at least 10^80, so we're still way fewer than that.<br />And, of course, considering the brain to be a lump of carbon is completely silly. The better bet would be to consider it water, approximate its volume, and divide by size of average neuron. Or, to be generous, the smallest neuron's diameter are around 4um (<a href="http://www.enchantedlearning.com/subjects/anatomy/brain/Neuron.shtml" rel="nofollow">source</a>), so call it 1um. Then, you get around 10^15 neurons, or 5x10^29 possible connections.<br /><br />An unrelated point: Your (or should I say "You") spelling and grammar -- quite entertaining.Eli Lanseyhttps://www.blogger.com/profile/01955234977479398457noreply@blogger.comtag:blogger.com,1999:blog-18103977.post-5695834861489716942009-09-08T18:39:12.938-04:002009-09-08T18:39:12.938-04:00Aryeh, there is no reason why the number of connec...Aryeh, there is no reason why the number of connections between objects cannot exceed the number of objects. In fact, it is usually the case that they do.<br /><br />Take five widgets numbered 1-5. To go from Widget 1 to Widget 5, I can go 1 5, 1 2 5, 1 3 5, 1 4 5, 1 2 3 5, 1 3 2 5, 1 3 4 5, 1 4 3 5, 1 4 2 5, 1 2 4 5, 1 2 3 4 5, 1 3 2 4 5, 1 3 4 2 5, 1 3 2 4 5, 1 4 3 2 5, 1 4 2 3 5, which is 17 possible pathways. Your count is only a calculation of direct linkages.<br /><br />Between all the cells in the brain, there will invariably be many more. However, you have to ask do all of these matter in any way, and the answer is probably not.notElonhttps://www.blogger.com/profile/04857651031212875523noreply@blogger.comtag:blogger.com,1999:blog-18103977.post-55348187082639813462009-09-08T15:54:16.354-04:002009-09-08T15:54:16.354-04:00you are apparently not the first to notice this ob...you are apparently not the first to notice this obvious misunderstanding of the basic concepts of the universe and logic which some phsychologists make.<br />http://www.scienceforums.net/forum/showthread.php?p=507888<br />It should be noted though that if they consider not the number of connections but the number of 'possible' connections then this claim is somewhat reasonable. A single Purkinje cell can regularly have 200,000 connections and so combinatorially there are quite a few possibilities. But as Bascule stated: "That's not a very useful definition of 'connection'. By that logic my sewage is connected to your drinking water."Lanseyhttps://www.blogger.com/profile/08825175323995592999noreply@blogger.com