title: Asymmetry in signal propagation between the soma and dendrites plays a key role in determining dendritic excitability in motoneurons.
abstract: It is widely recognized that propagation of electrophysiological signals between the soma and dendrites of neurons differs depending on direction, i.e. it is asymmetric. How this asymmetry influences the activation of voltage-gated dendritic channels, and consequent neuronal behavior, remains unclear. Based on the analysis of asymmetry in several types of motoneurons, we extended our previous methodology for reducing a fully reconstructed motoneuron model to a two-compartment representation that preserved asymmetric signal propagation. The reduced models accurately replicated the dendritic excitability and the dynamics of the anatomical model involving a persistent inward current (PIC) dispersed over the dendrites. The relationship between asymmetric signal propagation and dendritic excitability was investigated using the reduced models while varying the asymmetry in signal propagation between the soma and the dendrite with PIC density constant. We found that increases in signal attenuation from soma to dendrites increased the activation threshold of a PIC (hypo-excitability), whereas increases in signal attenuation from dendrites to soma decreased the activation threshold of a PIC (hyper-excitability). These effects were so strong that reversing the asymmetry in the soma-to-dendrite vs. dendrite-to-soma attenuation, reversed the correlation between PIC threshold and distance of this current source from the soma. We propose the tight relation of the asymmetric signal propagation to the input resistance in the dendrites as a mechanism underlying the influence of the asymmetric signal propagation on the dendritic excitability. All these results emphasize the importance of maintaining the physiological asymmetry in dendritic signaling not only for normal function of the cells but also for biophysically realistic simulations of dendritic excitability.
authors.affiliation: Division of Robotics Research, Daegu Gyeongbuk Institute of Science & Technology, Daegu, Korea; Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, United States of America.
authors.forename: Hojeong
authors.initials: H
authors.lastname: Kim
authors.affiliation: Centre for Neuroscience and Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Canada.
authors.forename: Kelvin E
authors.initials: KE
authors.lastname: Jones
authors.affiliation: Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, United States of America; Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, Chicago, United States of America; Department of Physical Therapy and Human Movement Science, Northwestern University Feinberg School of Medicine, Chicago, United States of America.
authors.forename: C J
authors.initials: CJ
authors.lastname: Heckman
mesh_terms: D003712:Dendrites / Q000502:physiology*; D015640:Ion Channel Gating; D007473:Ion Channels / Q000378:metabolism; D008959:Models, Neurological; D009046:Motor Neurons / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D007473:Ion Channels
references.citation: J Neurophysiol. 2006 Jan;95(1):225-41
references.pmid: 16267115
references.citation: J Neurophysiol. 2003 Aug;90(2):857-69
references.pmid: 12724367
references.citation: J Neurosci Methods. 2006 Sep 30;156(1-2):257-66
references.pmid: 16690134
references.citation: PLoS Comput Biol. 2010 May 13;6(5):e1000781
references.pmid: 20485556
references.citation: J Neurosci. 2009 Apr 22;29(16):5343-53
references.pmid: 19386931
references.citation: Nat Rev Neurosci. 2001 Mar;2(3):175-84
references.pmid: 11256078
references.citation: J Neurophysiol. 1992 Oct;68(4):1421-37
references.pmid: 1432090
references.citation: J Neurophysiol. 1982 Apr;47(4):606-21
references.pmid: 7069456
references.citation: Nat Neurosci. 2004 Sep;7(9):961-7
references.pmid: 15322550
references.citation: Neural Comput. 1997 Aug 15;9(6):1179-209
references.pmid: 9248061
references.citation: Ann N Y Acad Sci. 1962 Mar 2;96:1071-92
references.pmid: 14490041
references.citation: J Neurosci. 1995 Mar;15(3 Pt 1):1669-82
references.pmid: 7891127
references.citation: J Physiol. 1955 Nov 28;130(2):291-325
references.pmid: 13278904
references.citation: Nature. 1996 Jul 25;382(6589):363-6
references.pmid: 8684467
references.citation: J Physiol. 1989 Jul;414:265-82
references.pmid: 2607432
references.citation: Neuroscience. 2000;97(2):253-66
references.pmid: 10799757
references.citation: J Neurophysiol. 1998 Aug;80(2):583-93
references.pmid: 9705452
references.citation: Biophys J. 1993 Jul;65(1):423-49
references.pmid: 8369447
references.citation: Synapse. 2006 Jan;59(1):1-9
references.pmid: 16235229
references.citation: J Physiol. 2006 Jan 15;570(Pt 2):355-74
references.pmid: 16308349
references.citation: Trends Neurosci. 2003 Dec;26(12):688-95
references.pmid: 14624854
references.citation: Eur J Neurosci. 2000 May;12(5):1635-46
references.pmid: 10792441
references.citation: J Neurophysiol. 1990 Aug;64(2):648-60
references.pmid: 2213137
references.citation: J Comput Neurosci. 2011 Apr;30(2):301-21
references.pmid: 20623167
references.citation: J Neurophysiol. 1985 May;53(5):1323-44
references.pmid: 3839011
references.citation: J Comput Neurosci. 1995 Dec;2(4):299-312
references.pmid: 8746404
references.citation: PLoS One. 2012;7(8):e43654
references.pmid: 22916290
references.citation: Brain Res. 2002 Jun 21;941(1-2):11-28
references.pmid: 12031543
references.citation: J Neurol Neurosurg Psychiatry. 1988 Aug;51(8):1088-90
references.pmid: 3216211
references.citation: J Neurophysiol. 2008 Mar;99(3):1127-36
references.pmid: 18184885
references.citation: J Neurophysiol. 1993 Jan;69(1):241-7
references.pmid: 8381857
references.citation: Biophys J. 1973 Jul;13(7):648-87
references.pmid: 4715583
references.citation: Science. 2000 Oct 27;290(5492):739-44
references.pmid: 11052929
references.citation: J Neurosci. 2005 May 18;25(20):4985-95
references.pmid: 15901779
references.citation: J Neurophysiol. 1994 Apr;71(4):1468-79
references.pmid: 8035228
references.citation: Front Comput Neurosci. 2008 Dec 12;2:5
references.pmid: 19129908
references.citation: Neurosci Lett. 1998 Feb 27;243(1-3):61-4
references.pmid: 9535113
references.citation: J Neurophysiol. 2005 Dec;94(6):3961-74
references.pmid: 16120667
references.citation: J Neurophysiol. 2001 Oct;86(4):1955-71
references.pmid: 11600653
references.citation: Science. 2000 Oct 27;290(5492):744-50
references.pmid: 11052930
references.citation: J Neurophysiol. 2007 Aug;98(2):1042-7
references.pmid: 17522175
references.citation: J Neurophysiol. 1999 Apr;81(4):1531-47
references.pmid: 10200189
references.citation: J Neurophysiol. 1988 Jul;60(1):60-85
references.pmid: 3404225
references.citation: J Neurosci Methods. 1993 Feb;46(2):159-66
references.pmid: 8474259
references.citation: J Neurophysiol. 1999 Nov;82(5):2518-27
references.pmid: 10561423
references.citation: J Comput Neurosci. 2009 Dec;27(3):321-36
references.pmid: 19387812
references.citation: J Neurophysiol. 1998 Oct;80(4):2023-37
references.pmid: 9772258
references.citation: J Physiol. 1989 Feb;409:63-87
references.pmid: 2585300
references.citation: J Comput Neurosci. 2011 Jun;30(3):659-74
references.pmid: 20941536
references.citation: Annu Rev Neurosci. 2005;28:503-32
references.pmid: 16033324
references.citation: Physiol Rev. 1990 Apr;70(2):513-65
references.pmid: 1690904
references.citation: Nat Rev Neurosci. 2006 Apr;7(4):318-24
references.pmid: 16552417
references.citation: J Neurophysiol. 1998 May;79(5):2485-502
references.pmid: 9582222
references.citation: J Comp Neurol. 1987 Jan 1;255(1):68-81
references.pmid: 3819010
references.citation: J Comput Neurosci. 1994 Jun;1(1-2):39-60
references.pmid: 8792224
references.citation: Neuron. 2012 Jul 26;75(2):330-41
references.pmid: 22841317
references.citation: J Neurophysiol. 2003 Jan;89(1):27-39
references.pmid: 12522157
references.citation: J Neurophysiol. 2010 May;103(5):2599-610
references.pmid: 20164401