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Excitatory Effect of GABAergic Axo-Axonic Cells in Cortical Microcircuits
János Szabadics,1*
Csaba Varga,1*
Gábor Molnár,1*
Szabolcs Oláh,1
Pál Barzó,2
Gábor Tamás1
Abstract:
Axons in the cerebral cortex receive synaptic input at the axoninitial segment almost exclusively from -aminobutyric acidreleasing(GABAergic) axo-axonic cells (AACs). The axon has the lowestthreshold for action potential generation in neurons; thus,AACs are considered to be strategically placed inhibitory neuronscontrolling neuronal output. However, we found that AACs candepolarize pyramidal cells and can initiate stereotyped seriesof synaptic events in rat and human cortical networks becauseof a depolarized reversal potential for axonal relative to perisomaticGABAergic inputs. Excitation and signal propagation initiatedby AACs is supported by the absence of the potassium chloridecotransporter 2 in the axon.
1 Department of Comparative Physiology, University of Szeged, Közèp fasor 52, Szeged, H-6726, Hungary. 2 Department of Neurosurgery, University of Szeged, Közèp fasor 52, Szeged, H-6726, Hungary.
* These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail: gtamas{at}bio.u-szeged.hu
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