So I've just started trying to patch cells and I'm not having much luck.
I'm using spike2v5 basically as an ossilocope, with a time base of about
5 seconds, as I pass a 5mV step down the pipette (around 3MOhms K-
gluconate). I manually drive into the CA1 pyramidal cell layer with
positive pressure on. I first see a very transient drop in the current
trace (I assume this is entering the slice, if I reverse the pressure
here I always get nothing). If I keep driving in a bit I usually don't
really see a drop in the current, but the current trace goes a bit wavey,
occilating up and down. If I drop the pressure here I get a 15% drop in
current, (maybe 30% of the time) and if I put on negative pressure the
"seal" forms more.
But I don't get zero current, Maybe down to 40-30% of original... I start
to see some capacatinces transients, but I can't get the current down to
nothing, or go whole cell.
1) Is there any way to get a more definate signal when I approach a cell?
Or is it always subtle?
2) Do you thing I should try and increase my pipette resistance?
3) Any ideas on what I'm doing that makes it look live I've got a cell,
but yet I can't go whole cell (or even really on cell)?