Re: Earliest Animal Memory?

PiP: Hi Theo. I am not an expert in this area, but your question strikes
me as interesting enough that I want to throw in my two cents in the
hope that someone more knowlegeable addresses my points too.

ISTM that the answer depends on what you mean by a "memory". A fairly
broad definition of a biological "memory" would require the following
(at least):
- there is a physical record of past experiences.
- that record is consulted when determining future behaviors.
- both the recording of the record and the consulting of the record
are adaptations - abilities honed by natural selection because
they enhance fitness.



GS: The things you say above are exactly why the investigation of "memory"
has been so useless. There is no reason to believe that "there is a physical
record of past experiences"; that is "consulted." There is simply evidence
that experience alters behavior and that messing around directly with
physiology alters that fact. This suggests, of course, that physiology
mediates behavioral function, but does not suggest that anything is "stored"
and "retrieved." Are the selection pressures that alter species stored? Can
you look into the genome and see the selection contingencies that have
operated?

PiP: By this broad definition, even plants and bacteria have "memories".
Both short term and long term memories.



GS: Well, the whole point is moot. When we use the term "memory," or
"remembers," etc., the only common thread is that there is something that
happens in the past that affects, or appears to affect, behavior*.


PiP: But a narrower definition might limit "memories" to the kind of long
term animal memories that are believed to be physically recorded as
connections between neurons or as the "strengths" of those connections.
My guess would be that only animals with a CNS could have these kinds
of memories, and that ALL animals with a CNS have these kinds of
memories. But I'm not sure. Let me add my question to yours: In
simple CNS systems like C. elegans, do we have any evidence one way
or the other as to whether neuron connectivity or strength of connection
depends adaptively on experience.



GS: The point is that "memory" is a scientifically useless term. What
animals show habituation? Which ones show classical conditioning? Operant
conditioning? How does physiology mediate behavioral function. These are the
questions are the ones we should be asking. In addition, where they are
being asked, the conceptual framework needs to be better delineated: Kandel
is investigating the physiology of gill-withdrawal habituation, and there is
nothing stored, nor retrieved. The animal's physiology is altered as a
function of aspects of its ontogeny and, as a consequence, the animal
behaves in particular ways.



Cordially,



Glen



*GS: There are other aspects of the past that are relevant to our usage -
the thing must have been some sort of event that didn't operate
conspicuously on the person or animal - we do not usually say that the
alterations in behavior caused by head injuries are "memories," though we
certainly may say that there is an alteration of the mechanisms that
"constitute" memory.



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