Smad3 deficiency abolishes LTP induction in the DG after HFS of the MPP. (A) LTP induction in the DG of Smad3+/+ mice. (B) Smad3-/- mice do not exhibit evoked LTP in the DG. (C-D) HFS induces LTP in the CA1 region of Smad3+/+ and Smad3-/- mice. Raw fEPSP data (a) before tetanus, (b) 15 min and (c) 120 min after tetanus administration.