In a Posterior Parietal Cortex - TMS session, I managed to elicit very strong consistent MEPs along with a 60-70 ms long silent period from the PEC major muscle. I used a high intensity - 85% of the max intensity - single pulse, but there was no noticeable twitch in the arm or fingers.

The subject was holding a constant background contraction by pulling against a weight in the horizontal plane. What could be the reason? Are there studies that were able to induce MEPs by stimulating the parietal regions?