Modulation and function of the autaptic connections of layer V fast spiking interneurons in the rat neocortex
Open Access
- 14 June 2010
- journal article
- Published by Wiley in Journal Of Physiology-London
- Vol. 588 (12), 2047-2063
- https://doi.org/10.1113/jphysiol.2009.185199
Abstract
Neocortical fast-spiking (FS) basket cells form dense autaptic connections that provide inhibitory GABAergic feedback after each action potential. It has been suggested that these autaptic connections are used because synaptic communication is sensitive to neuromodulation, unlike the voltage-sensitive potassium channels in FS cells. Here we show that layer V FS interneurons form autaptic connections that are largely perisomatic, and without perturbing intracellular Cl(-) homeostasis, that perisomatic GABAergic currents have a reversal potential of 78 +/- 4 mV. Using variance-mean analysis, we demonstrate that autaptic connections have a mean of 14 release sites (range 4-26) with a quantal amplitude of 101 +/- 16 pA and a probability of release of 0.64 (V(command) = 70 mV, [Ca(2+)](o) = 2 mM, [Mg(2+)](o) = 1 mM). We found that autaptic GABA release is sensitive to GABA(B) and muscarinic acetylcholine receptors, but not a range of other classical neuromodulators. Our results indicate that GABA transporters do not regulate FS interneuron autapses, yet autaptically released GABA does not act at GABA(B) or extrasynaptic GABA(A) receptors. This research confirms that the autaptic connections of FS cells are indeed susceptible to modulation, though only via specific GABAergic and cholinergic mechanisms.This publication has 77 references indexed in Scilit:
- Regulation of cortical microcircuits by unitary GABA-mediated volume transmissionNature, 2009
- Postsynaptic Mechanisms Govern the Differential Excitation of Cortical Neurons by Thalamic InputsJournal of Neuroscience, 2009
- GABA Transporter GAT1 Prevents Spillover at Proximal and Distal GABA Synapses Onto Primate Prefrontal Cortex NeuronsJournal of Neurophysiology, 2009
- Perisomatic GABA Release and Thalamocortical Integration onto Neocortical Excitatory Cells Are Regulated by NeuromodulatorsNeuron, 2008
- Different transmitter transients underlie presynaptic cell type specificity of GABA A,slow and GABA A,fastProceedings of the National Academy of Sciences of the United States of America, 2007
- Axon Initial Segment Kv1 Channels Control Axonal Action Potential Waveform and Synaptic EfficacyNeuron, 2007
- Output of neurogliaform cells to various neuron types in the human and rat cerebral cortexFrontiers in Neural Circuits, 2007
- Enhancement of Spike-Timing Precision by Autaptic Transmission in Neocortical Inhibitory InterneuronsNeuron, 2006
- Variations on an inhibitory theme: phasic and tonic activation of GABAA receptorsNature Reviews Neuroscience, 2005
- Short-Term Synaptic PlasticityAnnual Review of Physiology, 2002