Chapter 18 – Synaptic plasticity

Synaptic responses undergo short- and long-term modifications. This chapter examines the mechanisms underlying plasticity in adult synapses. Developmental forms of plasticity are not covered here. The first form of long-term changes of synaptic efficacy is called hebbian plasticity and comprises long-term potentiation (LTP) and long-term depression (LTD). Moreover, there are several forms of LTP and LTD classified by their mechanisms and their mode of induction. We have chosen three examples, the NMDA receptor-dependent LTP, the metabotropic glutamate receptors (mGluR)-dependent LTD in the cerebellum and the spike-timing-dependent plasticity (STDP). The second, more recently discovered, form of long-term changes of synaptic efficacy is called homeostatic plasticity and occurs in response to prolonged changes in activity. Homeostatic plasticity can affect both excitatory and inhibitory synapses, but we have chosen the example of synaptic scaling at glutamatergic synapses to illustrate this type of plasticity.