I routinely made whole-cell patch-clamp w/ juvenile(4-7w) rat amygdala cells and had no problem.and recently I'm trying investigating adult(>10w) rat claustrum and having troubles.
I just... cant achieve gigohm seal....
Whichever neuron I try to approach seems getting swollen(poped) with a mild touch with recording pippet. else, still can't get gigaohm. sometimes the resistance gets higher a little, but returns to initial resistance soon(I guess the neuron got popped)
this happens seldom in juvenile amygdala... the resistance went gigaohm very easily by removing positive pressure.