LTP via NMDA in neocortex

brad nkeele at marlin.utmb.edu
Tue Mar 12 10:22:11 EST 1996


OK, good point Bill.

Perhaps I could elaborate a bit.  To definitively _PROVE_ that 
LTP is the neural/cellular correlate of learning and/or memory, 
it would be necessary to record changes in synaptic efficacy 
while the animal is actively engaged in the learning process.  
Typically, this has been addressed using extracellular recordings 
of field potentials.  It _may_ (highly qualified statement ahead) 
be that to pick up the subtle changes that occur during learning 
it is necessary to have a more sensitive measure (which may be 
beyond our technical know-how).  That is, feild potentials record 
ALL activity near the electrode, but it may be that only a few 
synapses were actually involved in the specific learning paradigm 
that is employed.  Of course, the other end of this spectrum is 
that recordings using intracellular electrodes (in vivo) may be 
TOO specific, i.e. recording from one neuron that may or may not 
be involved in the specific learning task.

PS: I like your mail server - IMO, the amygdala is a great part 
of the brain to be in just now.

In article <BILL.96Mar11134633 at amygdala.nsma.arizona.edu>, 
bill at nsma.arizona.edu says...
>
>nkeele at marlin.utmb.edu (brad) writes:
>
>   > . . . Another approach is to demonstrate that LTP 
>   > actually occurs while learning/memory is taking place 
(probably  
>   > can't be addressed with the technology available today).
>
>The problem is not so much inadequate technology as inadequate
>understanding of the molecular basis of LTP.  LTP is a 
long-lasting
>change in synaptic efficacy induced by strong, repetitive 
stimulation
>of certain pathways in the hippocampus.  Unfortunately, we don't 
yet
>fully understand the molecular changes that underlie this change 
in
>efficacy -- we understand a lot, and a little more each year, 
but not
>yet the whole story.  Consequently, when we perform a learning
>experiment and observe a change in synaptic efficacy -- and this 
has
>certainly been done -- we can never be quite sure that the 
molecular
>basis of this change is the same as the molecular basis of LTP. 
 If we
>really knew what LTP is, we would probably have the technology 
to
>recognize it.
>
>        -- Bill

-- 
______________________________________
N. Bradley Keele
Neuroscience Graduate Program
UTMB - Pharmacology J-31
Galveston, TX  77555-1031
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