We agree with Shors & Matzel's general hypothesis
that the proposed link between NMDA-dependent LTP and memory is
weak. They suggest that NMDA-dependent LTP is important to arousal
or attentional processes which influence learning in an anterograde
manner. However, current evidence is also consistent with the view
that NMDA receptors modulate memory consolidation retroactively,
as occurs in several other receptor classes.