Silent glutamatergic synapses in the mammalian brain

Excitatory synaptic transmission in the mammalian brain is mediated primari ly by alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) and N-me thyl-D-aspartate (NMDA) receptors that are thought to be co-localized at in dividual synapses. However, recent electrophysiological and anatomical data suggest that the synaptic localization of AMPA and NMDA receptors may be i ndependently regulated by neural activity. These data are reviewed here and the implications of these findings for the mechanisms underlying synaptic plasticity are discussed.