The Journal of Neuroscience, February 1, 2003, 23(3):859
Functional Autaptic Neurotransmission in Fast-Spiking
Interneurons: A Novel Form of Feedback Inhibition in the Neocortex
Alberto
Bacci,
John R.
Huguenard, and
David A.
Prince
Department of Neurology and Neurological Sciences, Stanford
University School of Medicine, Stanford, California 94305
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.
Key words:
interneurons; autapses; neocortex; synaptic
transmission; GABA; inhibition
Copyright © 2003 Society for Neuroscience 0270-6474/03/233859-08$05.00/0