LTP via NMDA in neocortex

Neal Prakash eamg061 at
Tue Mar 12 13:34:36 EST 1996

> 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 

this is not entirely beyond out technical ability--check out much of the 
work done by, for example, LB Cohen, A Grivnald, RD Frostig, EE Lieke in 
the 1970's-present using voltage sensitive-dyes and/or intrinsic signal 
optical imaging.  

Granted learning paradigms are difficult to check with these 
methods because of 
the need for non-anesthetized animals.  but the possibilty of observing 
functional plasticity in multiple (subthreshold) neurons is definitely 
feasible.  in 
fact it is already being done--check out Masino, SA et al, PNAS, in press 

> 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.

-neal prakash

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