You Must Remember This

Michael Jameson m.jameson at hunterlink.net.au
Sun Oct 21 11:53:00 EST 2001


et_al at my-deja.com wrote:

> On Tue, 16 Oct 2001 19:32:40 +1000, Michael Jameson
> <m.jameson at hunterlink.net.au> wrote:
>
> >The New Scientist article indicated that the general hypothesis has 'only
> >circumstantial evidence so far' - 'DNA certainly has the capacity to act as a
> >stable blueprint...
>
> And its this very point that makes me doubt the theory. DNA *is* fairly
> stable, yet this theory proposes to make it less so. Any one neuron may
> be involved in the 'storage' of many memories, so the DNA would have to
> be subtly modified for each one, which seems fraught with danger to me.
> How do you ensure that changes are only made to the "waste" 97%  and not
> the "active" 3%  where even a small change could have catastrophic
> effects for that cell.
>
> The second problem I can see is that memories are not permanent, cast in
> concrete, unchangeable things. My recollection of a past event can, and
> often does, change over the years. How does that fit with them being
> stored in "a stable blueprint"?  It seems to me this theory changes
> memory from, say, the malleability of this post stored on my HDD to the
> permanence of it being burnt into a CD and that doesn't seem to accord
> with reality.

Thanks. These both sound like fair criticisms to me.

> OTOH, the best theory we have, that storage is a product of the
> plasticity inherent in changes to cell interconnections, synaptic
> density, receptor types/placement/densities, etc, seems to be consistent
> with what occurs in practice. Moreover, we know these changes do occur.
>
> >> And no, more that 3% of the data are used.
> >> That would say that only 3% of the DNA were used to create a human during
> >> developement.
> >> It seems more data are required
> >
> >I don't understand. The abstract said that 'approximately 3% of our DNA is
> >used'. How are 'DNA' and 'data' interchangeable? Do you believe that 3%
> >figure to be incorrect?
>
> I don't know whether it is or not, but it seems probable.
>
> Every cell, including neurons, contains the entire DNA sequence needed
> to make any of the bodies cells, but a particular cell only needs to
> read a small part to function.  So that reduces the "active" percentage
> considerably.
>
> And quite a bit of the DNA is "junk" that we and our ancestors right
> back to the primordial soup have accumulated from transcription errors,
> viruses splicing parts of their DNA into it, charged particle damage,
> etc.
>
> Add that all up and the amount of DNA that controls a particular cell is
> probably fairly small, though I'm guessing that all may need to be in
> place for the cell to be viable.

Again, makes sense. That we don't see any use doesn't mean its place is
irrelevant.

> I don't think you could have a cell
> that only contained just the DNA sequences it needs. Which opens the
> possibility that while the cell may not actively use a particular
> section, that doesn't necessarily mean it isn't important in finding the
> right sections. Perhaps someone who knows more about this could comment.

Someone else did mention that the notion of 'junk' is basically only saying that
we can't say what it does.

> Ian

Mick.
--
"You are the music while the music lasts" - Antonio Damasio (after TS Eliot).





More information about the Neur-sci mailing list