Synaptic connections of axo-axonic (chandelier) cells in human epileptic temporal cortex.
The human temporal cortex contains a type of interneuron, identified by Golgi impregnation which, like the axo-axonic or chandelier cells found in animals, establishes Gray's type II synaptic contacts exclusively with the axon initial segments of pyramidal cells. Each terminal segment is composed of 3-12 boutons to form a "chandelier"-like appearance. For the two human axo-axonic cells analysed in this study we could identify 269 and 86 bouton rows respectively, which represents an equivalent number of postsynaptic pyramidal cells. A terminal bouton row from one of these Golgi-impregnated cells was shown to be in synaptic contact with the axon initial segment of a Golgi-impregnated pyramidal cell. The very specific nature of the target of axo-axonic cells, together with their highly divergent axonal arborization, means that they are ideally placed to control the output of a large population of pyramidal cells. Since previous studies in animals have shown the GABAergic nature of axo-axonic cells it is possible that human axo-axonic cells could be involved in the generation of epileptic activity or in the control of its propagation.
D000293:Adolescent; D001369:Axons / Q000473:pathology; D004833:Epilepsy, Temporal Lobe / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D013569:Synapses / Q000473:pathology; D009435:Synaptic Transmission; D013702:Temporal Lobe / Q000473:pathology* / Q000503:physiopathology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005680:gamma-Aminobutyric Acid