Dual intracellular recordings from microscopically identified neurons in the hippocampus
reveal that the synaptic terminals of three morphologically distinct types of interneuron
act through GABA(A) receptors. Each type of interneuron forms up to 12 synaptic contacts
with a postsynaptic principal neuron, but each interneuron innervates a different
domain of the surface of the postsynaptic neuron. Different kinetics of the postsynaptic
effects, together with the strategic placement of synapses, indicate that these GABAergic
interneurons serve distinct functions in the cortical network.