You Must Remember This

Michael Jameson m.jameson at hunterlink.net.au
Sun Oct 14 10:56:23 EST 2001


There was an article in the New Scientist of Sept 15 titled "You Must
Remember This", about the possiblility of DNA having a role in memory. I
can't summarise the three pages well - and there are dissenting opinions
quoted - but I will quote sentences which seem to demonstrate the
essential thesis:

"To lock a memory in place, most researchers say you need to shore up
its synaptic connections... But building permanent, stable connections
is no simple process. Nearly all of the brain's molecules, including
those that form the neural connections, are replaced every week or two.
How long-lasting memories can be stored with such distinctly impermanent
media has confounded theorists for years. The problem, says
neurobiologist Sandra Pena de Ortiz... is that molecular turnover would
eventually degrade these structural proteins... Electron microscopes
have also shown how far from stable neuroins are. Their outstretched
branches move from day to day... you could keep rebuilding the same
structures, but how would you know what to rebuild and where?... what's
needed is some sort of archived blueprint for each acquired
experience... "We believe that permanent memories are stored in altered
genes," says Pena. In the same way that DNA provides a blueprint for the
proteins that make up living cells, Pena and her colleague Yuri
Arshavsky... believe that new 'memory molecules' are born when altered
gene sequences are translated into proteins. They're not suggesting that
we make a new protein in the split second it takes to recall a memory.
"What I call molecules of memory," explains Pena, "are used to stabilise
networks of memory neurons." When a specific network is stabilised, so
is a particular memory."

I'd appreciate hearing any comment on this article or the general idea.

The paper that is the main focus of the article is "DNA recombination as
a possible mechanism in declarative memory" by Sandra Pena de Ortiz and
Yuri Arshavsky, Journal of Neuroscience Research, vol 63, p 72 (2001). A
second paper is also suggested as further reading, for which I found the
reference and abstract -

Journal of Theoretical Biology 2001 Jan 21;208(2):145-9
"Memory and DNA."
Dietrich A, Been W.
Institute of Human Genetics, University of Amsterdam, Academic Medical
Centre, Meibergdreef 15, NL 1105 AZ Amsterdam, The Netherlands.
a.dietrich at amc.uva.nl

A model is presented for the storage of long-term memory. In our model
consolidation takes place by specific DNA sequences. These DNA sequences
are obtained by the recombination of DNA in a similar way to that during
meiosis and the production of immunological antibodies. DNA has the
potential of the production of large numbers of specific DNA sequences.
These sequences can be attached to images of neural networks.The
following considerations lead to the theory: (1)Most of the DNA is not
used: approximately 3% of our DNA is used. (2)There are no cell
divisions in the brain after adulthood is reached. Structural DNA
arrangements will not be altered nor disrupted as a consequence of cell
division and mitosis. (3)Chromosomal pairing is demonstrated in the
brain, which could indicate the exchange of DNA. In addition, in our
first survey experiments we found a positive reaction of components of
the synaptonemal complex (SC) in the nuclei of brain cells. The SC is
highly meiosis specific and plays a major role in genetic recombination.

Copyright 2001 Academic Press.

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





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