[Neuroscience] Re: How to do extracellular recordings with glas micropipettes?

SJM Guzman jose.guzman at medizin-uni-leipzig.de
Fri Mar 3 03:52:27 EST 2006

Hi Christian:

It's always a pleasure to read you here. Thank you very much for your 
nice comments. Just a short question regarding your comments.

What did you mean with "We used an Axoclamp 2B. As far as I understand 
that's acutally an overkill"? I read quite a few good papers, where they 
used exactly this amplifier without any extra consideration.

Thank you very much in advance.

Christian Wilms wrote:
> Hi Thomas and Segundo!
> I've only done extracellular recording for a couple of days in a sommer
> course two years back, but I just grabbed my old notebook and found some
> of the information you guys are looking for. Maybe it turns out to be a
> of help for you:
>> > 1. What properties should the electrode have (compared to a
>> > conventional patch electrode e.g. resistance, shape, filling etc.)?
> We used glass pipettes filled with 2M NaCl. With this solution the
> pipettes we used averaged around 10MOhms.
>> > 2. Do I have to use a different headstage?
>>I don't think so. There're headstages specific for extracellular 
>>recordings, but I think those used in patch-clamp could work.
> As far as I remember we used the same headstage for patching and for
> extracellular recording.
>> > 3. Can I use my usual patch amplifier (Axoclamp 2B)?
> We used an Axoclamp 2B. As far as I understand that's acutally an
> overkill. I'm know of one lab that uses self-built amplifieres for
> recording extracellular signals in cerebellar slices. For those of us
> who are less inclined to build one, there are fairly simple
> field-potential amps to be had for relatively little money (the EXT
> module series from www.npielectronic.com for example).
>> > 5. Where to place the electrode (deep in the tissue or superficial)?
> THAT is the big question. It depends on what you want to see. The idea
> of current sinks and current sources is very central to understanding
> the whole concept of extracellular recording. There is a well written
> and informative chapter on this stuff to be found in:
> "Foundations of Cellular Neurophysiology" (Bradford Books (Hardcover))
> by Daniel Johnston and Samuel Maio-Sin Wu
> A personally believe that to be a very good starting point. Maybe some
> of the more experienced electrophysiologists in this group have some
> more to say on this.
> Regrads, Chris


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