Excitatory effect of GABAergic axo-axonic cells in cortical microcircuits.
Axons in the cerebral cortex receive synaptic input at the axon initial segment almost exclusively from gamma-aminobutyric acid-releasing (GABAergic) axo-axonic cells (AACs). The axon has the lowest threshold for action potential generation in neurons; thus, AACs are considered to be strategically placed inhibitory neurons controlling neuronal output. However, we found that AACs can depolarize pyramidal cells and can initiate stereotyped series of synaptic events in rat and human cortical networks because of a depolarized reversal potential for axonal relative to perisomatic GABAergic inputs. Excitation and signal propagation initiated by AACs is supported by the absence of the potassium chloride cotransporter 2 in the axon.
Szabadics
János
J
Department of Comparative Physiology, University of Szeged, Közèp fasor 52, Szeged, H-6726, Hungary.
Varga
Csaba
C
Molnár
Gábor
G
Oláh
Szabolcs
S
Barzó
Pál
P
Tamás
Gábor
G
D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000502:physiology*; D002540:Cerebral Cortex / Q000166:cytology* / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D009433:Neural Inhibition; D009474:Neurons / Q000502:physiology*; D017966:Pyramidal Cells / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D027981:Symporters / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000502:physiology; D000096922:K Cl- Cotransporters
D027981:Symporters; D005680:gamma-Aminobutyric Acid; D000096922:K Cl- Cotransporters; C119651:SLC12A7 protein, human