title: Convergence of pyramidal and medial brain stem descending pathways onto macaque cervical spinal interneurons.
abstract: We investigated the control of spinal interneurons by corticospinal and medial brain stem descending tracts in two macaque monkeys. Stimulating electrodes were implanted in the left pyramidal tract (PT), and the right medial longitudinal fasciculus (MLF), which contains reticulospinal, vestibulospinal, and some tectospinal fibers. Single unit discharge was recorded from 163 interneurons in the intermediate zone of the right spinal cord (segmental levels C(6)-C(8)) in the awake state; inputs from descending pathways were assessed from the responses to stimulation through the PT and MLF electrodes. Convergent input from both pathways was the most common finding (71/163 cells); responses to PT and MLF stimulation were of similar amplitude. Interneuron discharge was also recorded while the animal performed a reach and grasp task with the right hand; the output connections of the recorded cells were determined by delivering intraspinal microstimulation (ISMS) at the recording sites. Convergent input from MLF/PT stimulation was also common when analysis was restricted to cells that increased their rate during grasp (14/23 cells) or to cells recorded at sites where ISMS elicited finger or wrist movements (23/57 cells). We conclude that medial brain stem and corticospinal descending pathways have largely overlapping effects on spinal interneurons, including those involved in the control of the hand. This may imply a more important role for the brain stem in coordinating hand movements in primates than commonly assumed; brain stem pathways could contribute to the restoration of function seen after lesions to the corticospinal tract.
authors.affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
authors.forename: C Nicholas
authors.initials: CN
authors.lastname: Riddle
authors.forename: Stuart N
authors.initials: SN
authors.lastname: Baker
mesh_terms: D000200:Action Potentials; D000818:Animals; D001132:Arm / Q000502:physiology*; D001933:Brain Stem / Q000502:physiology*; D002574:Cervical Vertebrae; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004576:Electromyography; D005260:Female; D005385:Fingers / Q000502:physiology; D007839:Functional Laterality; D007395:Interneurons / Q000502:physiology*; D008253:Macaca mulatta; D009043:Motor Activity / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D011712:Pyramidal Tracts / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D014953:Wrist / Q000502:physiology
references.citation: Prog Neurobiol. 1987;28(2):161-95
references.pmid: 3544055
references.citation: J Neurosci. 2007 Jul 25;27(30):8053-8
references.pmid: 17652596
references.citation: Exp Brain Res. 1978 Sep 15;33(1):101-30
references.pmid: 699994
references.citation: J Physiol. 1994 Sep 15;479 ( Pt 3):463-73
references.pmid: 7837102
references.citation: J Comp Neurol. 1977 Jun 1;173(3):583-612
references.pmid: 404340
references.citation: J Neurosci. 1993 Feb;13(2):467-91
references.pmid: 8426224
references.citation: J Physiol. 1994 Oct 1;480 ( Pt 1):191-202
references.pmid: 7853222
references.citation: J Comp Neurol. 1985 Dec 1;242(1):56-92
references.pmid: 2416786
references.citation: J Neurophysiol. 1999 Dec;82(6):3580-5
references.pmid: 10601484
references.citation: Exp Neurol. 1964 Mar;9:212-27
references.pmid: 14130538
references.citation: J Comp Neurol. 1997 Jan 13;377(2):234-50
references.pmid: 8986883
references.citation: Biofizika. 1970 Jan-Feb;15(1):171-8
references.pmid: 5457895
references.citation: Exp Brain Res. 1977 Sep 28;29(3-4):323-46
references.pmid: 913521
references.citation: J Neurosci Methods. 1993 Sep;49(3):175-9
references.pmid: 8271837
references.citation: Exp Brain Res. 1985;59(2):353-64
references.pmid: 4029309
references.citation: J Neurosci. 2004 Sep 8;24(36):7804-13
references.pmid: 15356191
references.citation: J Physiol. 1992 Mar;448:397-412
references.pmid: 1593472
references.citation: J Comp Neurol. 1999 Aug 2;410(3):413-30
references.pmid: 10404409
references.citation: Prog Brain Res. 1964;12:222-45
references.pmid: 14202441
references.citation: J Physiol. 1999 Aug 1;518 ( Pt 3):895-906
references.pmid: 10420023
references.citation: J Neurophysiol. 2000 Aug;84(2):698-709
references.pmid: 10938297
references.citation: Exp Brain Res. 1981;42(3-4):269-81
references.pmid: 7238671
references.citation: J Physiol. 1962 Apr;161:91-111
references.pmid: 14461967
references.citation: Electroencephalogr Clin Neurophysiol. 1978 Aug;45(2):302-4
references.pmid: 78843
references.citation: Exp Brain Res. 2004 Jul;157(2):225-33
references.pmid: 15024538
references.citation: J Neurophysiol. 2008 Apr;99(4):2012-20
references.pmid: 18234981
references.citation: J Neurosci Methods. 1982 May;5(4):317-25
references.pmid: 6285087
references.citation: J Neurophysiol. 2006 Dec;96(6):2995-3005
references.pmid: 16943320
references.citation: Exp Brain Res. 1998 Dec;123(4):397-411
references.pmid: 9870600
references.citation: J Neurophysiol. 2004 Jul;92(1):83-95
references.pmid: 15014106
references.citation: J Physiol. 1975 Aug;249(3):617-36
references.pmid: 1177108
references.citation: J Neurophysiol. 2001 Oct;86(4):1573-86
references.pmid: 11600621
references.citation: Exp Brain Res. 2004 Dec;159(3):284-300
references.pmid: 15221165
references.citation: Brain Res Rev. 2008 Jan;57(1):134-46
references.pmid: 17936363
references.citation: J Neurophysiol. 2004 Nov;92(5):3142-7
references.pmid: 15175371
references.citation: J Neurophysiol. 2001 Feb;85(2):679-98
references.pmid: 11160503
references.citation: Brain. 1990 Dec;113 ( Pt 6):1843-56
references.pmid: 2276047
references.citation: Science. 1960 Jul 1;132(3418):38-40
references.pmid: 14413009
references.citation: J Neurophysiol. 1986 Jul;56(1):184-95
references.pmid: 3746394
references.citation: J Neurophysiol. 1998 Nov;80(5):2475-94
references.pmid: 9819257
references.citation: Brain. 1968 Mar;91(1):1-14
references.pmid: 4966862
references.citation: J Neurophysiol. 2006 Jun;95(6):3674-85
references.pmid: 16495365
references.citation: Brain. 1968 Mar;91(1):15-36
references.pmid: 4966860
references.citation: Brain. 1960 Mar;83:161-84
references.pmid: 14413010
references.citation: J Comp Neurol. 1962 Feb;118:107-37
references.pmid: 14461005
references.citation: J Physiol. 1993 Sep;469:213-43
references.pmid: 8271199
references.citation: J Neurophysiol. 2006 Nov;96(5):2229-52
references.pmid: 16837662
references.citation: J Neurophysiol. 2000 May;83(5):3147-53
references.pmid: 10805709
references.citation: J Neurosci. 2003 Mar 1;23(5):1867-78
references.pmid: 12629191
references.citation: Exp Brain Res. 2006 Aug;173(1):25-39
references.pmid: 16506008
references.citation: J Neurophysiol. 1945 Nov;8:387-92
references.pmid: 21004991
references.citation: Adv Neurol. 2001;87:25-40
references.pmid: 11347228
references.citation: J Neurophysiol. 2004 Apr;91(4):1722-33
references.pmid: 14668295
references.citation: Brain Res. 1985 Aug 12;340(2):341-54
references.pmid: 4027655
references.citation: J Neurosci. 2009 Apr 15;29(15):4993-9
references.pmid: 19369568
references.citation: J Neurophysiol. 1986 Feb;55(2):375-401
references.pmid: 3950696
references.citation: Exp Brain Res. 1976 Dec 22;26(5):509-19
references.pmid: 1010004
references.citation: J Neurosci. 1993 Dec;13(12):5105-18
references.pmid: 7504721
references.citation: J Comp Neurol. 1964 Jun;122:355-67
references.pmid: 14184859
references.citation: Brain Res. 1967 Oct;6(2):275-324
references.pmid: 6060511
references.citation: J Neurophysiol. 1968 Mar;31(2):166-75
references.pmid: 4879854
references.citation: J Neurophysiol. 2007 Jan;97(1):110-20
references.pmid: 16971685
references.citation: J Physiol. 1998 Aug 15;511 ( Pt 1):191-212
references.pmid: 9679174
references.citation: J Neurophysiol. 2006 Feb;95(2):1194-206
references.pmid: 16424458