[Neuroscience] Re: field IPSP recording in CA1 area

Bill via neur-sci%40net.bio.net (by connelly.bill from gmail.com)
Sun Aug 19 18:25:11 EST 2007

On Aug 18, 3:17 am, blueocea... from tom.com wrote:
> I got about 0.2 mv fIPSP (add APV and DNQX in the perfusion
> solution)and it can be demonished by 10um bicuculline.
> I place stimulate electrod in the middle third of stratum radiatum to
> stimulate schaffer collateral at 0.05Hz and the recording electrode in
> the pyramidale layer. But the maximum response I can get is only
> 0.2mv.  Anybody can give me suggestion to get larger fIPSP? I saw a
> paper said they can get 0.4mv fIPSP. Thanks!

Wow, I'm amazed you're even able to get it. We looked for these for a
while and where never able to get it. The classical way of getting
fEPSPs larger is to stimulate closer to your recording site, and would
have thought this would go double for fIPSPs because of the usually
short branching. Another way would be to reduce the chloride level in
your extracellular fluid (or I suppose increase it). To try and get
the chloride reversal potential further away from rest. We tried a
buffered solution of sodium acetate (126mM) without success, but we
didn't try very hard. You could try banging in an extra 20mM of NaCl.
I doubt that change in osmolarity would be very significant.

Finally, are you using glass or wire electrodes? Lower resistance
gives you a bigger sampling field I believe.

(P.S. Could you reply with the reference that says you can get
fIPSPs?. THanks)

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