GABAB receptor modulation of synaptic function

Neuromodulators have complex effects on both the presynaptic release and postsynaptic detection of neurotransmitters. Here we describe recent advances in our understanding of synaptic modulation by metabotropic GABA(B) receptors. By inhibiting multivesicular release from the presynaptic terminal, these receptors decrease the synaptic glutamate signal. GABA(B) receptors also inhibit the Ca2+ permeability of NMDA receptors to decrease Ca2+ signals in postsynaptic spines. These new findings highlight the importance of GABA(B) receptors in regulating many aspects of synaptic transmission. They also point to novel questions about the spatiotemporal dynamics and sources of synaptic modulation in the brain.