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

SJM Guzman jose.guzman at medizin-uni-leipzig.de
Wed Mar 1 08:16:41 EST 2006

Hi Thomas!

I had the same question some time ago, and I read some publications 
about field potentials (or extracellular recordings), but I couldn't get 
so much of them. I even tried in my preparation but unfortunately it 
didn't work. I would be very interested in getting the answers to your 
questions, or to contact with somebody with more experience about it. My 
answers here with my little experience

 > 1. What properties should the electrode have (compared to a
 > conventional patch electrode e.g. resistance, shape, filling etc.)?

A glass electrode filed with normal extracellular solution or 3M NaCl 
should be ok (I didn't read any description of the pipette resistance). 
Some people don't even use glass pipettes, and leave the metal electrode 
on the slice to get the recordings.

 > 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.

 > 3. Can I use my usual patch amplifier (Axoclamp 2B)?

As far as I know, the Axoclamp 2B is perfectly suitable for 
extracellular recordings. Some publications even refer to the use of the 
the axopatch-1D. In principle amplifiers of higher resolution are 
suitable for such recordings, but not the other way around.

 > 4. Should I use specific filters (usually I only use the 10 kHz filter
 > of the amp)

I found some extracellular recordings filtered at 1KHz and sampled at 2KHz.

 > 5. Where to place the electrode (deep in the tissue or superficial)?

Exactly the same conditions as for patch-clamp. Actually my idea was to 
do field recordings at the same time with patch-clamp.:P

I hope it helps!

I would apprecitate if somebody jump in here to check if the 
explanations are correct!

Segundo JM Guzman

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