The present study investigated the effects of a single oral dose (30 m
g) of the non-competitive N-methyl-D-aspartate (NMDA) receptor antagon
ist memantine on memory and learning in human subjects. Sixteen male h
ealthy volunteers participated in a double blind placebo controlled st
udy. There were no significant effects of memantine on mood, attention
or immediate and delayed verbal and visuospatial memory. Memantine di
d, however, delay the acquisition of classical eyeblink conditioning a
nd reduced the overall frequency of conditioned responses without affe
cting reflex or spontaneous eyeblinks. These findings are compatible w
ith the higher affinity of memantine to cerebellar as compared to fore
brain tissue and demonstrate the dissociability of different memory sy
stems by pharmacological tools. (C) 1997 Elsevier Science Ireland Ltd.