Hippocampal CA1 field recording

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Joseph Titus
Joseph Titus's picture
Hippocampal CA1 field recording

I am trying setup an extracellular rig to study the CA1 LTP.
I have one old set up was not working for many years and trying put back things to work.
I have Axopatch 200A amplifier, Grass S88 stimulator, an lab view acquisition program.
But I have the following issues with that set up.
Initially I was using interface chamber , where I could not maintain the proper bath level, when the high bath level,  response is low and when I reduce the level its becomes better. But after that the fEPSP amplitude started increasing, looks like my slice is drying..
Now I changed to submerged chamber, then If I keep high bath level again the response is low and I have to reduce the bath level here too.  I am using temperature controller to maintain the chamber but its not going beyond 26 C. Is it because of the temprature I am not getting proper response or any other problem in the setup? The over all gain is 500,  Low pass filter is 10kHz, I sthere anything with the settings I have to check ?
I have lot of DC shifts and the baseline is not stable.
I am not sure about my recoding electrode resistance, how do I measure the resistance?
Please help me to trouble shoot the issue

NishaR's picture
I have the same questions..

I have the same questions...Did you ever get any feedback to this post?

Abhinaba's picture
Hi Joseph and Nisha,

Hi Joseph and Nisha,
It has been a long time since u posted this topic. I hope u r getting good recordings. If not, try the following:

1.  Response decreases with high bath level:  means  higher resistance is coming in the circuit, which should not happen. So check the quality of your solution again(pH, osmolarity, expiry date of ingredients)...If not satisfied, make it again.

Optimise the position of the nozzle of the suction machine...keep in mind that chamber should not overflow.

2. Poor response can be due to inappropriate temp. There must be a mode switch to the right side of your heater..change it to manual mode and then turn the manual voltage controller...generally it is up to 12V...in our lab around 8V gives us 37*C. (While playing with the heater, ensure the flow of the bath  solution in the chamber!)

3. Your gain and Fc are subject to change as per your lab conventions.

4. For baseline prob : Check condition of the electrodes. If u r using Ag/AgCl electrode, plate it again.

5.Resistance:  Do u use glass micropipette on top of ur metal electrode for recording? then, fill it with recording solution, wait for two min...then put it on the metal electrode and drown in the bath.  You will find a resistance button in ur software interface.