Functional autaptic neurotransmission in fast-spiking interneurons: a novel form of feedback inhibition in the neocortex.
Autapses are synapses made by a neuron onto itself. Although morphological evidence for existence of autapses has been reported in several brain areas, it is not known whether such self-innervation in the neocortex is functional and robust. Here we report that GABAergic autaptic activity is present in fast-spiking, but not in low-threshold spiking, interneurons of layer V in neocortical slices. Recordings made with the perforated-patch technique, in which physiological intracellular chloride homeostasis was unperturbed, demonstrated that autaptic activity has significant inhibitory effects on repetitive firing and increased the current threshold for evoking action potentials. These results show that autapses are not rudimentary nonfunctional structures, but rather they provide a novel and powerful form of feedback inhibitory synaptic transmission in one class of cortical interneurons.
Bacci
Alberto
A
Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California 94305, USA.
Huguenard
John R
JR
Prince
David A
DA
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D007395:Interneurons / Q000145:classification / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D019579:Neocortex / Q000166:cytology / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010477:Perfusion; D011724:Pyridazines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D002614:Chelating Agents; D018756:GABA Antagonists; D011724:Pyridazines; D004533:Egtazic Acid; D005680:gamma-Aminobutyric Acid; C049853:gabazine; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid