title: Neural dynamics and information representation in microcircuits of motor cortex.
abstract: The brain has to analyze and respond to external events that can change rapidly from time to time, suggesting that information processing by the brain may be essentially dynamic rather than static. The dynamical features of neural computation are of significant importance in motor cortex that governs the process of movement generation and learning. In this paper, we discuss these features based primarily on our recent findings on neural dynamics and information coding in the microcircuit of rat motor cortex. In fact, cortical neurons show a variety of dynamical behavior from rhythmic activity in various frequency bands to highly irregular spike firing. Of particular interest are the similarity and dissimilarity of the neuronal response properties in different layers of motor cortex. By conducting electrophysiological recordings in slice preparation, we report the phase response curves (PRCs) of neurons in different cortical layers to demonstrate their layer-dependent synchronization properties. We then study how motor cortex recruits task-related neurons in different layers for voluntary arm movements by simultaneous juxtacellular and multiunit recordings from behaving rats. The results suggest an interesting difference in the spectrum of functional activity between the superficial and deep layers. Furthermore, the task-related activities recorded from various layers exhibited power law distributions of inter-spike intervals (ISIs), in contrast to a general belief that ISIs obey Poisson or Gamma distributions in cortical neurons. We present a theoretical argument that this power law of in vivo neurons may represent the maximization of the entropy of firing rate with limited energy consumption of spike generation. Though further studies are required to fully clarify the functional implications of this coding principle, it may shed new light on information representations by neurons and circuits in motor cortex.
authors: Laboratory for Neural Circuit Theory, RIKEN Brain Science Institute Wako, Saitama, Japan.
authors: Yasuhiro
authors: Y
authors: Tsubo
authors: Yoshikazu
authors: Y
authors: Isomura
authors: Tomoki
authors: T
authors: Fukai
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D006801:Humans; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009415:Nerve Net / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000502:physiology*
keywords: cortical layer; gamma oscillation; irregular firing; juxtacellular; local circuit; multiunit; neural code; synchronization
references: Neural Comput. 1995 Nov;7(6):1129-59
references: 7584893
references: Brain Res Rev. 2007 Oct;55(2):383-9
references: 17543390
references: Nat Rev Neurosci. 2003 Sep;4(9):739-51
references: 12951566
references: Nat Rev Neurosci. 2004 Oct;5(10):793-807
references: 15378039
references: Nature. 2012 Jul 5;487(7405):51-6
references: 22722855
references: Phys Rev Lett. 2007 Nov 30;99(22):228101
references: 18233330
references: IEEE Trans Neural Netw. 2004 Sep;15(5):1063-70
references: 15484883
references: Nat Neurosci. 2006 Nov;9(11):1432-8
references: 17057707
references: Nat Neurosci. 2010 Jun;13(6):739-44
references: 20436481
references: J Neurosci. 2008 Sep 10;28(37):9164-72
references: 18784297
references: Trends Cogn Sci. 2004 Aug;8(8):347-55
references: 15335461
references: PLoS Comput Biol. 2012;8(4):e1002461
references: 22511856
references: J Neurophysiol. 2005 Aug;94(2):1623-35
references: 15829595
references: J Neurophysiol. 1993 May;69(5):1661-72
references: 8389834
references: Neuron. 2006 Dec 7;52(5):871-82
references: 17145507
references: Neural Comput. 1995 Mar;7(2):307-37
references: 8974733
references: J Physiol. 2007 May 15;581(Pt 1):139-54
references: 17317752
references: Neuron. 2011 Nov 3;72(3):477-87
references: 22078507
references: Science. 1986 Sep 26;233(4771):1416-9
references: 3749885
references: J Physiol. 1948 Mar 15;107(2):165-81
references: 16991796
references: J Neurosci Methods. 1996 Apr;65(2):113-36
references: 8740589
references: J Neurosci. 2006 Apr 5;26(14):3875-84
references: 16597742
references: J Neurophysiol. 2000 Jul;84(1):401-14
references: 10899214
references: Neuron. 2009 Jan 29;61(2):301-16
references: 19186171
references: Biophys J. 1967 Nov;7(6):797-826
references: 19210999
references: Nat Neurosci. 1999 Nov;2(11):947-57
references: 10526332
references: Cereb Cortex. 2003 Jan;13(1):5-14
references: 12466210
references: Eur J Neurosci. 2007 Jun;25(11):3429-41
references: 17553012
references: Neurosci Res. 2004 Dec;50(4):381-94
references: 15567476
references: PLoS One. 2008;3(12):e3947
references: 19079601
references: Philos Trans R Soc Lond B Biol Sci. 2010 Aug 12;365(1551):2407-22
references: 20603361
references: J Neurophysiol. 2004 Oct;92(4):2283-94
references: 15381746
references: J Neurophysiol. 1993 May;69(5):1673-83
references: 8389835
references: Nat Neurosci. 2008 Mar;11(3):360-6
references: 18246064
references: Neural Comput. 2009 Jun;21(6):1714-48
references: 19191592
references: J Comp Neurol. 2004 Nov 22;479(4):360-73
references: 15514982
references: J Comp Neurol. 1982 Nov 20;212(1):76-88
references: 6294151
references: J Neurophysiol. 2012 Sep;108(6):1781-92
references: 22745461
references: Nat Rev Neurosci. 2010 Feb;11(2):127-38
references: 20068583
references: Sci Rep. 2012;2:485
references: 22761993
references: J Neurophysiol. 2005 Mar;93(3):1197-208
references: 15525802
references: Neurosci Res. 2004 Dec;50(4):395-410
references: 15567477
references: J Neurophysiol. 1996 Dec;76(6):3949-67
references: 8985892
references: Nat Neurosci. 2005 Dec;8(12):1677-83
references: 16261136
references: J Neurophysiol. 1998 Jan;79(1):159-73
references: 9425187
references: Nat Neurosci. 2009 Dec;12(12):1586-93
references: 19898469
references: Neural Comput. 2001 Jun;13(6):1285-310
references: 11387047
references: Phys Rev Lett. 2005 Apr 22;94(15):158101
references: 15904191
references: Cereb Cortex. 2013 Aug;23(8):1965-77
references: 22761308
references: Front Neurosci. 2009 Dec 15;3(3):337-43
references: 20198150
references: J Physiol. 1998 May 15;509 ( Pt 1):3-14
references: 9547376
references: Science. 2011 Jan 7;331(6013):83-7
references: 21212356
references: Nature. 2003 May 15;423(6937):288-93
references: 12748642
references: PLoS Comput Biol. 2011 Nov;7(11):e1002211
references: 22096452
references: Eur J Neurosci. 2010 Jan;31(2):263-72
references: 20074217
references: Somatosens Mot Res. 1993;10(3):269-89
references: 8237215
references: Nature. 2003 Nov 27;426(6965):442-6
references: 14647382
references: Front Neuroinform. 2010 Mar 22;4:6
references: 20431724
references: Neural Comput. 2003 Sep;15(9):2179-98
references: 12959671
references: J Neurophysiol. 2007 Jan;97(1):208-19
references: 16956986
references: Nature. 2003 Feb 20;421(6925):844-8
references: 12594513
references: Nat Neurosci. 2008 May;11(5):535-7
references: 18376400
references: Neuron. 2008 Nov 26;60(4):683-97
references: 19038224
references: Trends Cogn Sci. 2003 Dec;7(12):553-9
references: 14643372
references: Front Neuroinform. 2012 Mar 19;6:5
references: 22448159
references: J Neurophysiol. 2004 Aug;92(2):1182-98
references: 15028746
references: J Comput Neurosci. 2007 Oct;23(2):189-200
references: 17387606
references: Biophys J. 2007 Jan 15;92(2):683-95
references: 17192317
references: Nat Neurosci. 1998 Jul;1(3):210-7
references: 10195145
references: Neural Comput. 1996 Jul 1;8(5):979-1001
references: 8697231
references: J Neurosci. 2004 Sep 29;24(39):8441-53
references: 15456817
references: Proc Natl Acad Sci U S A. 1986 Nov;83(21):8390-4
references: 3464958
references: Proc Natl Acad Sci U S A. 1993 May 15;90(10):4470-4
references: 8506287
references: J Neurophysiol. 2004 Jul;92(1):600-8
references: 15056678
references: J Comput Neurosci. 2005 Jun;18(3):287-95
references: 15830165
references: J Neurophysiol. 2007 Jun;97(6):4235-57
references: 17376854
references: J Neurosci. 2011 Jul 13;31(28):10380-91
references: 21753015
references: J Neurosci. 2007 Dec 12;27(50):13802-12
references: 18077692