title: Monosynaptic convergence of chorda tympani and glossopharyngeal afferents onto ascending relay neurons in the nucleus of the solitary tract: a high-resolution confocal and correlative electron microscopy approach.
abstract: Physiological studies suggest convergence of chorda tympani and glossopharyngeal afferent axons onto single neurons of the rostral nucleus of the solitary tract (rNTS), but anatomical evidence has been elusive. The current study uses high-magnification confocal microscopy to identify putative synaptic contacts from afferent fibers of the two nerves onto individual projection neurons. Imaged tissue is revisualized with electron microscopy, confirming that overlapping fluorescent signals in confocal z-stacks accurately identify appositions between labeled terminal and dendrite pairs. Monte Carlo modeling reveals that the probability of overlapping fluorophores is stochastically unrelated to the density of afferent label, suggesting that convergent innervation in the rNTS is selective rather than opportunistic. Putative synaptic contacts from each nerve are often compartmentalized onto dendrite segments of convergently innervated neurons. These results have important implications for orosensory processing in the rNTS, and the techniques presented here have applications in investigations of neural microcircuitry with an emphasis on innervation patterning.
authors: Department of Psychology, University of Virginia, Charlottesville, Virginia, 22904, USA.
authors: James A
authors: JA
authors: Corson
authors: Alev
authors: A
authors: Erisir
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D002814:Chorda Tympani Nerve / Q000166:cytology*; D003712:Dendrites / Q000648:ultrastructure; D003911:Dextrans / Q000378:metabolism; D005930:Glossopharyngeal Nerve / Q000166:cytology*; D021621:Imaging, Three-Dimensional; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008959:Models, Neurological; D009010:Monte Carlo Method; D009474:Neurons / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012235:Rhodamines / Q000378:metabolism; D016622:Silver Staining; D017552:Solitary Nucleus / Q000166:cytology*; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure*; D013649:Taste / Q000502:physiology
chemical_list: D003911:Dextrans; C067661:Fluoro-Ruby; D012235:Rhodamines; C076397:biotinylated dextran amine; D001710:Biotin
keywords: brainstem; convergence; gustation; primary afferent innervation
references: J Comp Neurol. 1986 Feb 1;244(1):72-85
references: 3950091
references: Nat Neurosci. 2006 Sep;9(9):1117-24
references: 16892056
references: J Comp Neurol. 2006 Feb 10;494(5):738-51
references: 16374812
references: J Neurosci Methods. 2000 Apr 15;97(2):175-81
references: 10788671
references: Brain Res Bull. 1988 May;20(5):545-8
references: 3382964
references: Nat Rev Neurosci. 2010 Dec;11(12):823-36
references: 21068766
references: J Neurophysiol. 2006 Nov;96(5):2513-27
references: 16899635
references: J Neurophysiol. 1991 Jun;65(6):1452-63
references: 1875254
references: Curr Opin Neurobiol. 2009 Aug;19(4):370-7
references: 19674892
references: J Neurophysiol. 2010 Apr;103(4):1771-84
references: 20107132
references: J Comp Neurol. 2006 Aug 1;497(4):658-69
references: 16739199
references: Curr Protoc Neurosci. 2005 Aug;Chapter 2:Unit 2.8
references: 18428619
references: J Neurosci. 2009 Jul 22;29(29):9227-38
references: 19625513
references: Brain Res. 2004 Sep 10;1020(1-2):62-72
references: 15312788
references: Kumamoto Med J. 1965 Jun 30;18(2):106-8
references: 5825888
references: J Neurosci. 2009 Nov 4;29(44):13919-28
references: 19890002
references: Neuroscience. 2008 Oct 15;156(3):653-61
references: 18789377
references: J Neurosci Methods. 2008 Jun 30;171(2):296-308
references: 18471891
references: Brain Res. 1971 Dec 24;35(2):584-8
references: 5135555
references: Brain Res. 1999 Aug 7;837(1-2):289-97
references: 10434014
references: J Neurophysiol. 1995 Jul;74(1):249-57
references: 7472328
references: J Cell Physiol. 1965 Aug;66(1):1-17
references: 5857910
references: J Comp Neurol. 1988 Dec 15;278(3):388-96
references: 2464006
references: J Neurophysiol. 1996 Nov;76(5):2919-27
references: 8930244
references: Science. 2012 Jan 20;335(6066):353-6
references: 22267814
references: J Comp Neurol. 1988 Oct 22;276(4):547-72
references: 2461969
references: Curr Pain Headache Rep. 2003 Oct;7(5):377-83
references: 12946291
references: J Neurophysiol. 2012 Dec;108(12):3301-12
references: 23019002
references: Neuron. 2009 Jan 29;61(2):247-58
references: 19186167
references: Brain Res. 1995 Aug 21;689(2):289-98
references: 7583333
references: Curr Opin Neurobiol. 2008 Jun;18(3):321-31
references: 18804167
references: J Comp Neurol. 2007 Jun 20;502(6):1066-78
references: 17444498
references: Neuron. 2010 Sep 23;67(6):1009-20
references: 20869597
references: Brain Res. 1993 Dec 31;632(1-2):161-73
references: 8149226
references: J Comp Neurol. 1994 Jun 1;344(1):50-64
references: 8063955
references: J Comp Neurol. 1990 Nov 22;301(4):554-74
references: 2177063
references: J Neurophysiol. 1995 Jun;73(6):2144-62
references: 7666129
references: Nat Protoc. 2009;4(8):1145-56
references: 19617886
references: J Neurophysiol. 1964 Jul;27:635-44
references: 14194963
references: Brain Res. 1986 Feb 19;365(2):305-20
references: 3947995
references: Brain Res. 1978 Mar 24;143(2):281-97
references: 630410
references: J Neurophysiol. 2011 Feb;105(2):697-711
references: 21106899
references: Proc Natl Acad Sci U S A. 2009 Jun 30;106(26):10835-40
references: 19541658
references: Brain Res. 1988 Aug 2;457(1):1-11
references: 3167557
references: Neuron. 2006 Mar 16;49(6):861-75
references: 16543134
references: J Comp Neurol. 1996 Apr 01;367(2):205-21
references: 8708005
references: J Comp Neurol. 2012 Feb 15;520(3):495-527
references: 21800298
references: Neuron. 2011 Jan 27;69(2):273-86
references: 21262466
references: Jpn J Physiol. 1966 Dec 15;16(6):599-611
references: 5298469
references: Neuroscience. 2009 Oct 20;163(3):920-32
references: 19596055
references: J Physiol. 1968 Nov;199(1):223-40
references: 5684036
references: J Comp Neurol. 1997 Jan 27;377(4):535-49
references: 9007191
references: Neuroscience. 1996 May;72(1):185-97
references: 8730716
references: J Histochem Cytochem. 1990 May;38(5):717-20
references: 1692056
references: J Neurophysiol. 2006 Feb;95(2):674-85
references: 16267112
references: Audiology. 1991;30(3):125-34
references: 1953442
references: J Comp Neurol. 2005 Nov 28;492(4):495-509
references: 16228991
references: J Comp Neurol. 2005 Apr 18;484(4):458-73
references: 15770654
references: J Comp Neurol. 2001 Dec 10;441(2):168-85
references: 11745643