Chandelier or axo-axonic cells are the most selective of all cortical GABAergic interneurons,
because they exclusively contact axon initial segments of cortical glutamatergic neurons.
Owing to their privileged location on initial segments, axo-axonic cells have often
been assumed to have the ultimate control of pyramidal cell output. Recently, key
molecules expressed at the initial-segment synapses have been identified, and novel
in vitro and in vivo electrophysiological studies have revealed unexpectedly versatile
functional effects exerted by axo-axonic cells on their postsynaptic targets. In addition,
there is also emerging recognition of the mechanistic involvement of these unique
cells in several neurological diseases, including epilepsy and schizophrenia.