Featured Review Cellscience Reviews Vol 3 No 3 ISSN 1742-8130

The role of the NR2 NMDA receptor subunits in visual cortical plasticity

The molecular mechanisms underlying experience-dependent modification of synaptic strength are likely to be of fundamental importance in learning and memory. Within the visual system, two naturally occurring synaptic strength modalities, potentiation and depression, can be detected in response to monocular deprivation, and each of these changes requires activation of the N-methyl-D-aspartate receptors (NMDARs). NMDARs are a subtype of glutamate receptor, and the ratio of synaptic NMDAR subunits, NR2A to NR2B (the NR2A:NR2B ratio), changes with age and in response to visual experience. It has been proposed that, since the NR2 subunit composition largely determines the kinetic properties of the NMDAR, an NR2A:NR2B ratio change likely alters the threshold for synaptic strengthening. This property of a ‘sliding’ synaptic strength threshold is known as metaplasticity and recent evidence supports this mechanistic model.

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