spontaneous IPSC vs. mininature IPSC

r norman rsnorman_ at _comcast.net
Mon May 26 08:03:24 EST 2003


On Mon, 26 May 2003 14:57:44 +0800, Wen Zhang
<wenw_zhang at yahoo.com.cn> wrote:

>I've read a few papers mentioned both, but I can't figure out the
>difference between them. Can anyone give me a few explanation?

You don't give any citations or any other information for us to guess
just what you mean, but here is some "classical" synaptic physiology
where they refer to exactly the same phenomenon.

In 1952, Fatt and Katz discovered very small end-plate potentials that
were generated spontaneously at the frog neuromuscular junction. Fatt
P and Katz B (1952) "Spontaneous subthreshold activity at motor nerve
terminals" J Physiol 117:108-128.  These were called "mepp" for
miniature end-plate potentials, but they were also called "spontaneous
minis" to indicate that you didn't have to stimulate anything to
produce them.  Subsequent work showed that they were caused by single
"quanta" (vesicles) of transmitter being released from the presynaptic
terminal.

You refer to "IPSC".  Presumably that means that the same phenomena is
being observed at an inhibitory synapse and that, instead of recording
post-synaptic potential with a microelectrode, the system is voltage
clamped and post-synaptic current is being measured.  Hence
"inhibitory post-synaptic current".  The notion of spontaneous and
miniature still apply with the original meaning.  

So, the short answer is that "spontaneous" and "miniature" refer to
two different aspects of the same thing.





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