I am having problem inducing LTP in hippocampal slices. This set up was working well before and for some reason it is not working now. I am getting good input and output but I am unable to induce LTP. If anyone had this kind of problem and what should be done to troubleshoot this. Hippocampal slices look healthy and I have checked all the buffers, oxygen/c02 and electrodes. I appreciate some answer on this issue. Thanks.