Terry and Ben,
I never implied anything that could be considered a "memory" at a conscious level is stored at just one synapse, but all the discussions I have heard of learning in various brain science books and lectures imply synaptic weights are the main place of our memories are stored. Yes, Hebbian learning would appear to use a neuron wide signal that a neuron has fired, but the actual Hebbian learning is only believed to take place at individual synapses as a function of the relationship of the timing between the synapse's up- and downstream neurons. So all the Hebbian and Hebbian-like learning I have ever heard described distinguishes between which of a neuron's synapses are to have their weights changed by how much and/or in what direction. Now there may well be other mechanisms which would allow long term memory to be stored at a neuron-wide level, but I can't at the moment remember reading or hearing of any. That is not proof they don't exist, but it, at least it suggests that, so far, the evidence for such mechanism that has been learned is underwhelming. On the other hand, I have read or heard probably at least a thousand times about the brain storing information in synapses. Ed Porter -----Original Message----- From: Terren Suydam [mailto:[EMAIL PROTECTED] Sent: Wednesday, December 03, 2008 2:00 PM To: [email protected] Subject: RE: [agi] Lamarck Lives!(?) Ed, Though it seems obvious that synapses are *involved* with memory storage, it's not proven that synapses individually *store* memories. Clearly memory is distributed, as evidenced by brain injury studies (a situation that led Karl Pribram/David Bohm to propose a holographic storage metaphor). In other words, memories might be stored as patterns of synaptic/neural dynamics, in which the relevant scope is well higher than at the level of the individual synapse. Given that memory storage is not so simple as to depend crucially on individual synapses, I see no serious problems with a neuron-wide mechanism of memory storage. Also, think of Hebbian learning, in which synaptic strength is reinforced based on a neuron-wide signal. Terren --- On Wed, 12/3/08, Ed Porter <[EMAIL PROTECTED]> wrote: > From: Ed Porter <[EMAIL PROTECTED]> > Subject: RE: [agi] Lamarck Lives!(?) > To: [email protected] > Date: Wednesday, December 3, 2008, 1:33 PM > I don' really see how a change in gene expression in the > nucleus of a neuron > caused by methylation could store long term memories, since > most neural > network models store all most all their information in the > location and > differentiation of they synapses. > > How is information in a neural net stored by making what > would appear to be > only neuron-wide behaviors? Such a global change might be > valuable for > signally that a record of recent events in the neuron at a > give brief period > of time, should be stored, but it would not appear to > actually keep them > stored over a long period of time. > > I think the article failed to mention an important part of > the theory of > what is going on. > > Ed Porter > > -----Original Message----- > From: Terren Suydam [mailto:[EMAIL PROTECTED] > Sent: Wednesday, December 03, 2008 12:16 PM > To: [email protected] > Subject: RE: [agi] Lamarck Lives!(?) > > > Ed, > > That's a good point about synapses, but perhaps the > methylation just affects > the neuron's output, e.g., the targeted genes express > proteins that only > find a functional role in the axon. > > Terren > > --- On Wed, 12/3/08, Ed Porter <[EMAIL PROTECTED]> > wrote: > > Richard, > > > > The role played by the epigenome in genetics actually > does > > have a slightly > > Lamarckian tinge. Nova had a show saying that when > > identical twins are born > > their epigenomes are very similar, but that as they > age > > their epigenomes > > start to differ more an more, and that certain > behaviors > > like drinking or > > smoking can increase the rate at which such changes > take > > place. > > > > What I didn't understand about the article you > linked > > to is that it appears > > they are changing the epigenome to change the > expression of > > DNA, but as far > > as I know DNA only appears in the nucleus (with the > > exception of > > mitochondirial DNA), and thus would appear to affect > the > > cell as a whole, > > and thus not be good at differentially affecting the > > strengths of different > > synapses --- as would presumably be required for most > > neuronal memory --- > > unless the nuclear DNA had some sort of mapping to > > individual synapses, or > > unless local changes to mitochondrial DNA, near a > synapse > > are involved. The > > article does not appear to shed in any light on this > issue > > of how changes in > > the expression of DNA would affect learning at the > synapse > > level, where most > > people think it occurs. > > > > Ed Porter > > > > -----Original Message----- > > From: Richard Loosemore [mailto:[EMAIL PROTECTED] > > Sent: Wednesday, December 03, 2008 11:12 AM > > To: [email protected] > > Subject: [agi] Lamarck Lives!(?) > > > > > > Am I right in thinking that what these people: > > > > > http://www.newscientist.com/article/mg20026845.000-memories-may-be-stored-on > > -your-dna.html > > > > > > are saying is that memories can be stored as changes > in the > > DNA inside > > neurons? > > > > If so, that would upset a few apple carts. > > > > Would it mean that memories (including cultural > > adaptations) could be > > passed from mother to child? > > > > Implication for neuroscientists proposing to build a > WBE > > (whole brain > > emulation): the resolution you need may now have to > > include all the DNA > > in every neuron. Any bets on when they will have the > > resolution to do that? > > > > > > > > Richard Loosemore > > > > > > > > ------------------------------------------- > > agi > > Archives: > https://www.listbox.com/member/archive/303/=now > > RSS Feed: > https://www.listbox.com/member/archive/rss/303/ > > Modify Your Subscription: > > https://www.listbox.com/member/?&; > > Powered by Listbox: http://www.listbox.com > > > > > > > > ------------------------------------------- > > agi > > Archives: > https://www.listbox.com/member/archive/303/=now > > RSS Feed: > https://www.listbox.com/member/archive/rss/303/ > > Modify Your Subscription: > > https://www.listbox.com/member/?&; > > Powered by Listbox: http://www.listbox.com > > > > > > ------------------------------------------- > agi > Archives: https://www.listbox.com/member/archive/303/=now > RSS Feed: https://www.listbox.com/member/archive/rss/303/ > Modify Your Subscription: > https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com > > > > ------------------------------------------- > agi > Archives: https://www.listbox.com/member/archive/303/=now > RSS Feed: https://www.listbox.com/member/archive/rss/303/ > Modify Your Subscription: > https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com ------------------------------------------- agi Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: https://www.listbox.com/member/?&; Powered by Listbox: http://www.listbox.com ------------------------------------------- agi Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: https://www.listbox.com/member/?member_id=8660244&id_secret=120640061-aded06 Powered by Listbox: http://www.listbox.com
