As there is evidence on the local secretion of BDNF at the presynaptic terminals shortly after tetanus59 and it has also been reported that tetanus induced the enhancement in BDNF mRNA expression at postsynaptic neuron with a time course well correlated with L-LTP expression and HFS-induced mBDNF secretion in distal dendrites,9,32 it is tempting to speculate that the requirement of BDNF at stage I involves presynaptic mechanism, while the requirement of BDNF at stage II is due to the involvement of postsynaptic mechanism. Here, BDNF is linked to tetanus.