Question on Schaffer Collateral

Hi,

I'm new to electrophysiology techniques as I did my undergrad in Human genetics. Right now I'm trining in 'in vivo' electrophysiology techniques. Lowering a bipolar stimulation electrode and a recording electrode into the hippocampus to induce LTP by using three trains of HFS at 200 hrz within 5 minute intervals at the Schaffer Collateral.

I'm getting my response at a depth of approx 2.8-3.1 mm down depending on the rat which are 310-400 g in weight. However even though I am getting a good baseline at 50% I/O curve and applying HFS at 75% I am having difficulty inducing LTP.

I'm using the point of inversion of the positive to negative sigal as the recording electrode is lowered into the same layer as the already lowered stimulation electrode as my new point 0 and lower my electrodes to a depth of about 250-350 depending on the max amplitude of the EPSP for both the recording and stimulation electrodes.

Does anyone have any suggestions for induction of LTP?

Hi.

You first should check your Intra and Extra solutions, if something is in there, that could block LTP, or something is missing to allow LTP. Compare them to LTP papers.

Do you at least see shorttime plasticity?