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An electrophysiology quesiton

k p Collins kpaulc at [----------]earthlink.net
Wed Feb 11 15:26:19 EST 2004

"r norman" <rsn_ at _comcast.net> wrote in message
news:t6fk20p1t94usn5pe21pgsr5u58541ar50 at 4ax.com...
> 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!


If you transform the information-content
inherent in "all the switching" [what the
Experimenter must do to actually extract
meaning from the results he is observing]
you will end-up at the position I've dis-

That is, take the manual steps in the Ex-
perimental procedure, extract the inform-
ation-content inherent in the manual steps,
Transform that information-content into
attributes intrinsic to the neuron that's be-
ing studied, and you'll arrive at the position
I've been discussing.


The goal is to see how neurons work, not
how experimental procedures work.

The "Classical" approach 'just' throws-out
the information-content inherent in exper-
imental procedures' manual steps.

It's a Sorrowful-Waste.

K. P. Collins

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