We agree with Shors & Matzel's general hypothesis that the proposed li
nk between NMDA-dependent LTP and memory is weak. They suggest that NM
DA-dependent LTP is important to arousal or attentional processes whic
h influence learning in an anterograde manner. However, current eviden
ce is also consistent with the view that NMDA receptors modulate memor
y consolidation retroactively, as occurs in several other receptor cla
sses.