Ionotropic Glutamate Receptors in Synaptic Plasticity

Summary

More than 30 years have elapsed since the publication of the first reports of long-term potentiation by Bliss and Lomo (1973) and Bliss and Gardner-Medwin (1973). These two reports ushered in an exciting new era in which measurable persistent changes in synaptic strength were posited as substrates for learning and memory. Since that time, the study of long-term mechanisms of synaptic plasticity have arguably been one of the most intensely and perhaps the most rewarding fields of the neurosciences, casting important light on the nature of synaptic transmission and the events associated with the strengthening or weakening of synapses. Indeed, although once principally studied at excitatory glutamatergic synapses within the hippocampus and cortical formations, mechanisms of synaptic plasticity are observed at a myriad of synaptic connections throughout the mammalian central nervous system. Moreover, although many of these synapses share common mechanisms of plasticity, the last decade has seen an explosion in our understanding of plasticities peculiar to one synapse or another. This chapter does not attempt to cover all of these divergent mechanisms but instead focuses on those mechanisms of long-term potentiation (LTP) and depression (LTD) most commonly found within the hippocampal formation. A large portion of this review covers N-methyl-\fontsize77\selectfont D-aspartate–receptor-dependent LTP and LTD, the two most commonly studied forms of cortical plasticity; however, it also addresses plasticity mechanisms at other hippocampal synapses that have not enjoyed the same intensity of investigation but are worthy of attention.