There are two types of inhibitory postsynaptic potentials in the cerebral cortex.
Fast inhibition is mediated by ionotropic gamma-aminobutyric acid type A (GABA(A))
receptors, and slow inhibition is due to metabotropic GABA(B) receptors. Several neuron
classes elicit inhibitory postsynaptic potentials through GABA(A) receptors, but possible
distinct sources of slow inhibition remain unknown. We identified a class of GABAergic
interneurons, the neurogliaform cells, that, in contrast to other GABA-releasing cells,
elicited combined GABA(A) and GABA(B) receptor-mediated responses with single action
potentials and that predominantly targeted the dendritic spines of pyramidal neurons.
Slow inhibition evoked by a distinct interneuron in spatially restricted postsynaptic
compartments could locally and selectively modulate cortical excitability.
