title: Continuous modulation of action potential firing by a unitary GABAergic connection in the globus pallidus in vitro.
abstract: The firing patterns of neurons in the globus pallidus (GP) are affected by two major sources of GABAergic inhibition: striatal afferents and local axon collaterals. Local GABAergic GP-GP synapses display short-term depression (STD) and very sparse connectivity. At the high presynaptic firing rates typical in the GP, one would expect this STD to be complete, practically cancelling the postsynaptic impact of the synapse. To investigate the apparent paradox of a synapse not affecting its postsynaptic neuron, we performed dual whole-cell recordings in acute brain slices from rats and recorded, for the first time, unitary IPSPs from a GP-GP GABAergic connection. We show that at high presynaptic firing rates the unitary connection continuously modulates the postsynaptic firing rate through a combination of large chloride driving force, unitary IPSP summation, and incomplete synaptic depression. Our findings indicate that, despite substantial STD and sparse connectivity, local GABAergic axon collaterals in the GP may echo the changes in presynaptic firing frequency across postsynaptic targets.
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel.
authors.forename: Jenia
authors.initials: J
authors.lastname: Bugaysen
authors.forename: Izhar
authors.initials: I
authors.lastname: Bar-Gad
authors.forename: Alon
authors.initials: A
authors.lastname: Korngreen
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001703:Biophysics; D004558:Electric Stimulation; D005260:Female; D058787:GABA-A Receptor Antagonists / Q000494:pharmacology; D059330:GABAergic Neurons / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D005917:Globus Pallidus / Q000166:cytology*; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D008297:Male; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid
chemical_list: D058787:GABA-A Receptor Antagonists; D005680:gamma-Aminobutyric Acid; C013411:biocytin; D008239:Lysine; D001640:Bicuculline
references.citation: Neuroscience. 2005;135(3):791-802
references.pmid: 16154280
references.citation: Eur J Neurosci. 2008 Dec;28(12):2401-8
references.pmid: 19087170
references.citation: Prog Neurobiol. 2003 Dec;71(6):439-73
references.pmid: 15013228
references.citation: Nat Neurosci. 1999 Feb;2(2):144-50
references.pmid: 10195198
references.citation: J Comp Neurol. 2000 Jan 31;417(1):17-31
references.pmid: 10660885
references.citation: J Neurosci. 2007 Mar 7;27(10):2525-38
references.pmid: 17344390
references.citation: J Neurosci. 2013 Apr 24;33(17):7130-44
references.pmid: 23616523
references.citation: Brain Res. 1988 Jun 21;453(1-2):353-6
references.pmid: 2900056
references.citation: J Neurophysiol. 2002 Sep;88(3):1263-9
references.pmid: 12205147
references.citation: Nat Neurosci. 1999 May;2(5):467-72
references.pmid: 10321252
references.citation: PLoS One. 2010 Aug 06;5(8):e12001
references.pmid: 20700458
references.citation: PLoS One. 2012;7(9):e45421
references.pmid: 23028997
references.citation: Brain Res. 1994 Feb 14;636(2):308-19
references.pmid: 8012814
references.citation: J Physiol. 2012 Nov 15;590(22):5861-75
references.pmid: 22890706
references.citation: J Neurosci. 2002 Jun 15;22(12):5164-72
references.pmid: 12077211
references.citation: J Comp Neurol. 1984 Aug 1;227(2):182-99
references.pmid: 6470212
references.citation: J Neurosci. 2007 Jun 13;27(24):6352-62
references.pmid: 17567796
references.citation: Front Syst Neurosci. 2011 Mar 30;5:16
references.pmid: 21483725