BDNF has been shown to trigger the activation and nuclear translocation of MAPK in hippocampal neurons.35,51 Application of MAPK inhibitors either during or shortly after tetanus markedly attenuated L-LTP at CA1 synapses, suggesting that MAPK is critical for the full expression of BDNF-dependent forms of L-LTP.6,52,53 We now demonstrate that MAPK is required not only for stage I, but also for stage II. The gene discussed is BDNF; the disease is tetanus.