An electrophysiology quesiton

r norman rsn_ at _comcast.net
Wed Feb 11 09:39:55 EST 2004


On Wed, 11 Feb 2004 09:17:34 +0000, Xiaoshen Li <xli6 at gmu.edu> wrote:

>Matt,
>
>Thank you for your wonderful reply. It clears my mind a lot.
>
>Now I understand that, when somebody shows an action potential curve or 
>a neuron is bursting, most of time that was obtained by current clamp 
>experiment.(Voltage clamp holds the neuron at certain membrane potential 
>below the AP threshold, therefore the neuron cannot go through 
>Hodgkin-Huxley cycle).
>For single channel studies, voltage-clamp is used.
>
>To study synaptic transmission, I am still unclear why sometimes an 
>electrophysiologist wants to measure EPSC and sometimes EPSP. (I read a 
>paper which talks about EPSP data for a while, then EPSC data for a 
>while. My eyes were searching "P" or "C" and my mind cannot follow the 
>logic behind it).
>
>
Voltage clamping is much more difficult to do.  There is nothing to a
"current clamp".  Just stick an electrode into a cell (which isn't
that easy) and record! To do a voltage clamp, the techniques are far
more elaborate.  So, unless the information you seek absolutely
requires voltage clamp data (currents under very controlled
potential), you just record the potential and interpret it in terms of
the channels opening and the currents flowing.  

You eventually get used to all the switching.  Well, you don't get
used to it, but eventually you learn to deal with it!





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