Re: New Scientist on memory

From: Dace (
Date: Sun 01 Jun 2003 - 04:28:09 GMT

  • Next message: Keith Henson: "_Religion Explained_ by Pascal Boyer"

    > From:
    > > >
    > > > > Though the author himself doesn't seem to realize it, the evidence
    > > > > discussed in this article abolishes the notion that the brain
    > > > > alone is responsible for memory. Every time we recall something,
    > > > > the relevant memory trace in the brain is completely erased and
    > > > > then "reconstituted" from scratch. If memory is nothing more than
    > > > > stored information in the brain, there would be no way of
    > > > > recreating the memory once it's been erased. The only explanation
    > > > > is that we literally recall the past (often making mistakes in the
    > > > > process) enabling us to reconstruct the memory after the neural
    > > > > trace has been destroyed. Memory must be taken at face value-- as
    > > > > a recollection of the past-- rather than simply the retrieval of
    > > > > information from cerebral vaults. We may regard neural traces as
    > > > > pointers to memories rather than the memories themselves.
    > > > >
    > > > > --TD
    > > > >
    > > > The article states that memory is not 'erased' so much as it is
    > > > 'redynamized';
    > >
    > > Every time you remember something, the relevant "memory trace" in your
    > > brain is erased. Ordinarily, you simply re-establish the trace,
    > > perhaps in modified form, in the act of recalling the event from the
    > > past. But if something interferes with your ability to re-establish
    > > the trace, such as a drug that stops protein-synthesis, you lose the
    > > memory. The trace, which had already been erased, is now gone for
    > > good. It's in the gap between recall, when the neural trace has been
    > > liquidated, and the moment the trace is re-established, that the true
    > > nature of memory is revealed. During that gap, your brain cannot help
    > > you remember. It's up to you.
    > >
    > The memory is not erased, it is simply 'fluidified', that is, 'unfixed'
    > its memory storage moorings. But it is still there during the active
    > remembrance. It must be 'refixed' if it is to remain, and that usually
    > happens by the very act of remembrance. However, this 'refixing'
    > process can be interdicted by certain drugs. In this case, the 'unfixed'
    > memory simply dissipates, thatis, it is forgotten, rather than being
    > 'refixed' in memory storage.

    When a memory is recalled, it must be "fixed" or forgotten. If lack of protein prevents "reconstitution," the memory is gone. If there were a backup-- a copy of the memory before it was recalled-- why would it be erased at the very moment the attempt to re-fix it fails? This doesn't make any sense. Clearly, the original memory trace is gone from the very moment the memory is recalled, but this absence is revealed only when reconstitution fails. Once the memory trace becomes "fluid," it no longer has the structure that made it a memory trace. There is thus no backup, no piece of the old memory we can revert to once the new version fails. There's simply nothing.

    This is what's so shocking and why some researchers, such as Cahill at UC Irvine, refuse to believe it despite numerous replications of this experiment on several species of animals. The new finding throws the whole field into turmoil. What this means is that there is no memory trace during the crucial period when the memory is being reconstituted. All during the
    "fixing" process, nothing physically guides the way. We remember on the basis of nothing-- at least nothing in the brain. How could this be? For memory research this is the end of the world as we know it.

    Why is it that highly evolved creatures have no method of retaining memories in the event that reconstitution fails? Why hasn't the environment selected for animals that won't lose important memories just because they lack sufficient protein when memories are called up? If we're going to tamper with a memory, and the tampering could easily go wrong, why not make a backup copy? But then, if the memory doesn't consist of stored information in the first place, how could it be copied?

    The brain does not contain records of memories but mere "traces" that point us to them. A trace can be wiped clean at the moment we remember it because, now that we recall it, we don't need the trace anymore. But we'll need it the next time we want to recall it. So the trace is re-fixed. But if the fix isn't carried out, there's nothing left, no "dynamized" or
    "fluidified" or "unmoored" relic. Simply nothing.

    > From: Lawrence DeBivort (
    > Dace, '"reconstituted" from scratch' sounds like an unmitigated
    > in terms to me. Can you explain how it isn't?

    It is a contradiction, Lawry. You can't reconstitute something from nothing, and there's nothing in the brain that could provide the model for reconstituting a memory trace once the memory is recalled. Therefore reconstitution of the memory trace proceeds through active recollection of the past. Without true memory, a trace would indeed have to be reconstituted from scratch-- an impossibility.


    =============================================================== This was distributed via the memetics list associated with the Journal of Memetics - Evolutionary Models of Information Transmission For information about the journal and the list (e.g. unsubscribing) see:

    This archive was generated by hypermail 2.1.5 : Sun 01 Jun 2003 - 04:31:55 GMT