An electrophysiology quesiton

Xiaoshen Li xli6 at gmu.edu
Wed Feb 11 07:22:12 EST 2004


Dr. Norman,

It is nice to hear from you. Your post is short, so it is very unclear. 
I disagree with you on several things based on what I guess you are 
trying to say. First, V-clamp is not harder than I-clamp to do. There is 
a switch on the machine to choose V-clamp or I-clamp. It is just a 
matter of click. In terms of clamping error which Dr. Matt Jones 
mentioned is another issue.(Maybe this is the issue you hinted). That is 
for the synapse far from soma while one is patching on the soma. If 
under I-clamp mode, the amplifier doesn't care how much current flow 
in/out of the neuron membrane(I am very surprised with this information 
and I have asked again for confirmation/explanation in my previous post, 
because if so, I-clamp is not clamping anything), clamping error doesn't 
exist.
I have never heard that I-clamp data is less convincing than V-clamp. My 
impression is that they are with same rigorous. V-clamp and I-clamp are 
two different techniques to measure different things. They are not just 
different names one has to get used to it.

Sincerely,
Xiaoshen

r norman wrote:

> 
> 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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