I am trying to record fEPSPs in the mouse mPFC and use an LTP protocol:
Stimulating electrode in layer II/III, recording electrode in layer V
Stimulate with 4-6 trains, 100 pulses, 100 Hz, with a intertrain interval of 30s
Right now my issue is that I am having a lot of noise, which my PI and I have attributed to the glass pipette because when record using whole-cell patch clamp and evoke currents there is no noise.
Can anyone provide suggestions on how to pull a proper glass/recording pipette?
Hi Sarah,
The field recordings may be much more sensitive to noise, as you are amplifying much smaller signals (0.2-2mV) and you need to apmlify them 100-1000 times. What noise (frequency) do you see? 60Hz? Anywhere along the way from the pipette to the amplifier input your wires may serve as an antenna. In general, the patch-pipette is can be same as the fEPSP recording pipette. Your issue originates in poor ground. Try to ground the batch, suction, ACSF flow etc.
We have solved the noise issue in field recordings by having high concentration of solution, 3M of NaCL in low resistance electrodes between 1-2MOhm; then to avoid solution leaking which kills your cells, we imobilize the solution with agarose; 0.75% to 1% agarose depending on the one you have.