We are recording muscle spasticity in rats after spinal cord injury when stimulation is applied. While recording, we see that there is more deflection in one direction (either positive or negative depending on the arrangement of the electrodes themselves) than the other. Just looking for any possible causes and solutions. I attached an example of this uneven deflection.

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I added a picture of our current setup. For the recording and ground electrodes, we are using patch electrodes that only make contact with the surface of the tail. The red and white clamps are the recording and the black is the ground. The stimulating electrode we are using is a cuff style electrode. This is the yellow electrode seen closer to the tip of the tail. We are acquiring the patch electrodes from Biopac, the same company that produces the clamps that the electrodes attach to and the hardware we are using to record and shock with. The stimulating electrode is made in our lab. It is made from 1/8 inch inner diameter tygon tubing that has silver wire threaded through that has been soldered to a conducting wire. The patch electrodes already come with adhesive on them but we use velcro cable ties to ensure that the electrodes are making contact with the tail. We have tried altering the placement of the clamps on the electrodes but nothing seems to eliminate the uneven deflection.