SJM Guzman <jose.guzman at medizin-uni-leipzig.de> wrote:
> If this ratio is >1 they talk about paired-pulse facilitation (PPF), if
> S2/S1<1 they call it paired-pulse inhibition (PPI)....
>> My question is... are those effects always presynaptic? if yes, why?
As was already mentioned PPF is normally attributed to residual calcium
in the presynapse and PPI to depletion of the readily releasable pool.
The lab of Wade Regehr has done a lot of (quite beautiful actually) work
on presynaptic calcium and looking through the piles of papers on my
desk I found one that might be of interest to you:
"Interplay between Facilitation, Depression, and Residual Calcium at
Three Presynaptic Terminals"
Jeremy S. Dittman, Anatol C. Kreitzer, and Wade G. Regehr
The Journal of Neuroscience, February 15, 2000, 20(4):1374-1385