I often find that the hippocampal slice has poor contact with the MEA 2100-Lite-System. For example, only a part of the slice area can give a good signal. Who has already solved this problem, can you help me?

I am registering LTP at CA1 and DG. I know the slices are alive. I checked slices of this animal in another station with the setting of electrodes using micromanimulators.