Hey I recommend for that age to use a chilled and oxygenated choline chloride solution (see attachment- two stock solutions 1. NaHCO3 2.the rest, without Choline chloride and w/o CaCl2 that you add fresh daily) for heart perfusion before removing the brain and for slicing . Make coronal slices without dissecting your hippocampus. separate the two hemispheres and make a cut between CA3 and CA1. Slice at 300uM or 400 uM. Keep your slices at 33C for recovery and turn down the temp to RT for the rest of the day. Also do you have to heat for your experiment? At higher temperatures the slices degrade pretty fast, but it is doable. Also check your rig flow. It has to be pretty stable to keep stable recordings and reliable LTP. Finally are you using picrotoxin on your ASCF? If not, add 100uM final ptx to your ACSF. Let me know if you have more questions and good luck!

also if you place your recording electrode in Radiatum not very close of the somas of CA1, then you will get a clean fEPSP and no contamination from the spikes. It is easier to measure the fEPSP amplitude that way, and also, instead of using the amplitude, calculate the slope for each fEPSP at the first 1/3 of the decay. That way you also avoid contamination with spikes. Perform always a input output curve before recording your baseline and use 40-50% stim value. Baseline can be sometimes very long until you reach stability. If it is pretty unstable, then check your flow...that will help with stability. And to me it is more reliable to stimulate with TBS x3 or x5 than with HFS.

Hi Paula,

Thank you for your help. No, I didn't have picrotoxin in the aCSF. I tried adding 1uM gabazine to the acsf (as we had it to hand) and cut CA3 and it seems to have helped!