Most excitatory and inhibitory neurotransmitter receptors are concentrated at the postsynaptic density (PSD) facing pre-synaptic terminals containing the corresponding neurotransmitter [1–3]. The preferential accumulation of receptors at synapses is achieved by their specific interactions with a molecular scaffold that links them to the underlying cytoskeleton [4,5]. This scaffold forms the so-called PSD, which acts as a molecular machine and locally controls some aspects of synapse formation, maintenance, plasticity and function. In recent years, the use of single-molecule and real-time imaging has revealed that neurotransmitter receptors are in constant, rapid movement at the neuronal surface and are transiently trapped at PSDs so as to modify the number and composition of receptors that are available to respond to released neurotransmitter [6–8]. Such is the case for the glycine receptor (GlyR), the GABAA receptor (GABAAR), the glutamate α-amino-3-hydroxy-5-methyl-4-isoxazole pro-pionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors, indicating that the phenomenon can be generalized. This dynamic behavior has profoundly modified our view of the synapse. The aim of this chapter is to review some aspects of our knowledge on receptor dynamics.
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