Development of central pattern generating circuits

Current Opinion in Neurobiology

Volumn 15, Issue 1, 2005, Pages 86-93

  Marder, Eve ^a   Rehm, Kristina J ^a  

^a BRANDEIS UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

TRANSCRIPTION FACTOR;

EMBRYO DEVELOPMENT; INVERTEBRATE; MOLECULAR DYNAMICS; MOTONEURON; NERVE CELL NETWORK; NERVOUS SYSTEM DEVELOPMENT; NEUROTRANSMISSION; NONHUMAN; PRIORITY JOURNAL; PROTEIN FUNCTION; REVIEW; SPINAL CORD; VERTEBRATE;

EID: 13844264524     PISSN: 09594388     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.conb.2005.01.011     Document Type: Review

References (89)

1. L.C. Katz, and C.J. Shatz Synaptic activity and the construction of cortical circuits Science 274 1996 1133 1138
2. F. Clarac, F. Brocard, and L Vinay The maturation of locomotor networks Prog Brain Res 143 2004 57 66 This recent review focuses on the maturation of locomotion primarily by comparing adult with neonatal rat preparations.
3. E. Marder, and R.L. Calabrese Principles of rhythmic motor pattern generation Physiol Rev 76 1996 687 717
4. E. Marder, and D Bucher Central pattern generators and the control of rhythmic movements Curr Biol 11 2001 R986 R996
5. Bekoff A Spontaneous embryonic motility: an enduring legacy Int J Dev Neurosci 19 2001 155 160
6. L.D. Milner, and L.T. Landmesser Cholinergic and GABAergic inputs drive patterned spontaneous motoneuron activity before target contact J Neurosci 19 1999 3007 3022
7. M.G. Hanson, and L.T. Landmesser Characterization of the circuits that generate spontaneous episodes of activity in the early embryonic mouse spinal cord J Neurosci 23 2003 587 600 The authors recorded from isolated mouse spinal cord-limb preparations as early as embryonic day 11 (E11) when many motor neurons have not yet reached their targets. These preparations generate spontaneous rhythmic activity that depends heavily on cholinergic transmission, presumably because the motor neurons themselves are involved in burst generation. Moreover, anatomical evidence suggests the presence of motor neuron collaterals that form a precocious circuit responsible for the generation of this activity.
8. M.G. Hanson, and L.T. Landmesser Normal patterns of spontaneous activity are required for correct motor axon guidance and the expression of specific guidance molecules Neuron 43 2004 687 701 In this elegant study, the authors apply pharmacological agents in ovo at specific times during development. They then look at the levels of spontaneous activity, the position of the motor neuron somata, and the expression of EphA4, polysialic acid on neural cell adhesion molecule (NCAM) and LIM homeodomain transcription factors. They conclude from these experiments that rhythmic bursting activity is necessary for spinal motor neurons to make correct pathfinding decisions early in development.
9. B. Yvert, P. Branchereau, and P Meyrand Multiple spontaneous rhythmic activity patterns generated by the embryonic mouse spinal cord occur within a specific developmental time window J Neurophysiol 91 2004 2101 2109 The authors describe the evolution of spontaneous activity in the embryonic mouse spinal cord. On embryonic days E12.5 and E13.5, they recorded regularly recurring short spike-episodes synchronized across most of the cord. By E14.5 longer lasting episodes separated by longer time intervals appeared, whereas at E15.5, the long episodes disappeared. At E16.5, the cervical rhythm became stronger, but the lumbar activity dropped. Finally, at E17.5, short episodes of spontaneous activity resumed at caudal levels. The authors interpret their results to mean that at E14.5, a single network starts to split into locally organized regional networks.
10. J.C. Norreel, J.F. Pflieger, E. Pearlstein, J. Simeoni-Alias, F. Clarac, and L Vinay Reversible disorganization of the locomotor pattern after neonatal spinal cord transection in the rat J Neurosci 23 2003 1924 1932
11. S. Pagliardini, J. Ren, and J.J. Greer Ontogeny of the pre-Botzinger complex in perinatal rats J Neurosci 23 2003 9575 9584 The pre-Bötzinger complex is a group of neurons thought to serve as a pacemaker for the vertebrate respiratory system. Because the respiratory circuits must function as soon as the animal is born, and respiratory rhythms are easy to record, this is an ideal system in which to study development. In this study, immunocytochemistry and electrophysiology were used to study the pre-BötzC in rats from E15 to postnatal day 7. Birth dating of neurons in the ventrolateral medulla suggests that pre-BötzC neurons are born around E12.5-E13.5, and the onset of rhythmical respiratory discharge occurs around E17.
12. J. Ren, and J.J. Greer Ontogeny of rhythmic motor patterns generated in the embryonic rat spinal cord J Neurophysiol 89 2003 1187 1195 These authors used in vitro spinal cord and medullary-spinal cord preparations isolated from rats at E13.5-E21.5 to characterize age-dependent changes in the motor patterns generated at different times during development. At E13.5-E15.5, the spinal networks generated rhythmic activity depending on cholinergic and glycinergic synaptic interconnections. At later stages (E18.5-E21.5), glutamatergic signalling by way of non-NMDA receptors appears primarily responsible, whereas during the middle period (E16.5-E17.5), a complex mixture of synaptic mechanisms is involved. These changes in neurotransmitter use are accompanied by alterations in the equilibrium potential for chloride, as chloride-mediated synaptic potentials shift from primarily excitatory to inhibitory before the animals are born.
13. M.L. Suster, and M Bate Embryonic assembly of a central pattern generator without sensory input Nature 416 2002 174 178
14. B. Casasnovas, and P Meyrand Functional differentiation of adult neural circuits from a single embryonic network J Neurosci 15 1995 5703 5718
15. Y. Le Feuvre, V.S. Fénelon, and P Meyrand Unmasking of multiple adult neural networks from a single embryonic circuit by removal of neuromodulatory inputs Nature 402 1999 660 664
16. K.S. Richards, W.L. Miller, and E Marder Maturation of the rhythmic activity produced by the stomatogastric ganglion of the lobster, Homarus americanus J Neurophysiol 82 1999 2006 2009
17. K.S. Richards, D.J. Simon, S.R. Pulver, B.S. Beltz, and E Marder Serotonin in the developing stomatogastric system of the lobster, Homarus americanus J Neurobiol 54 2003 380 392 Serotonin immunoreactivity first appears in identified sensory neurons that project to the stomatogastric ganglion only in early larval stages. Nonetheless, serotonin transporters and receptors are already present in the embryo. The presence of a serotonin transporter in the embryonic stomatogastric ganglion suggests serotonin could be functioning as a 'borrowed transmitter' subsequent to hormonal liberation from the pericardial organs. The physiological neuromodulatory actions of serotonin are more pronounced early in development.
18. P. Wenner, and M.J. O'Donovan Mechanisms that initiate spontaneous network activity in the developing chick spinal cord J Neurophysiol 86 2001 1481 1498
19. M Goulding How early is firing required for wiring? Neuron 43 2004 601 603
20. 2+ spike activity in embryonic spinal cord neurons in Xenopus do not affect expression of markers of cell identity, but do change their neurotransmitter. Suppression of activity led to more neurons with excitatory transmitters and fewer neurons with inhibitory transmitters. The opposite was seen when activity was enhanced.
21. B. Yang, J.D. Slonimsky, and S.J. Birren A rapid switch in sympathetic neurotransmitter release properties mediated by the p75 receptor Nat Neurosci 5 2002 539 545
22. P.A. Getting Emerging principles governing the operation of neural networks Annu Rev Neurosci 12 1989 185 204
23. A. Roberts, S.R. Soffe, E.S. Wolf, M. Yoshida, and F.Y. Zhao Central circuits controlling locomotion in young frog tadpoles Ann N Y Acad Sci 860 1998 19 34
24. S Grillner The motor infrastructure: from ion channels to neuronal networks Nat Rev Neurosci 4 2003 573 586 This is an excellent review focusing primarily, but not exclusively, on the organization of the lamprey spinal cord. The author takes the reader from cellular mechanisms all the way to behavior.
25. E. Jankowska Spinal interneuronal systems: identification, multifunctional character and reconfigurations in mammals J Physiol 533 2001 31 40
26. B.A. Bannatyne, S.A. Edgley, I. Hammar, E. Jankowska, and D.J. Maxwell Networks of inhibitory and excitatory commissural interneurons mediating crossed reticulospinal actions Eur J Neurosci 18 2003 2273 2284
27. W.C. Li, S. Higashijima, D.M. Parry, A. Roberts, and S.R. Soffe Primitive roles for inhibitory interneurons in developing frog spinal cord J Neurosci 24 2004 5840 5848 The authors suggest that a class of interneurons with a single function early in development might subdivide later into neurons with different functions.
28. L. Cheng, A. Arata, R. Mizuguchi, Y. Qian, A. Karunaratne, P.A. Gray, S. Arata, S. Shirasawa, M. Bouchard, and P. Luo Tlx3 and Tlx1 are post-mitotic selector genes determining glutamatergic over GABAergic cell fates Nat Neurosci 7 2004 510 517 In this study the authors address the issue of how developing neurons in the spinal cord select transmitters. The authors present evidence suggesting that the homeobox genes Tlx3 and Tlx1 are important in the decision between glutamate and GABA expression.
29. A. Kania, and T.M. Jessell Topographic motor projections in the limb imposed by LIM homeodomain protein regulation of ephrin-A:EphA interactions Neuron 38 2003 581 596
30. S.E. Cheesman, M.J. Layden, T. Von Ohlen, C.Q. Doe, and J.S. Eisen Zebrafish and fly Nkx6 proteins have similar CNS expression patterns and regulate motoneuron formation Development 131 2004 5221 5232 Overexpression of fish or fly Nkx6 results in supernumerary motor neurons in both zebrafish and flies, suggesting an ancestral function for Nkx6 proteins in motor neuron development.
31. M. Goulding, G. Lanuza, T. Sapir, and S Narayan The formation of sensorimotor circuits Curr Opin Neurobiol 12 2002 508 515
32. K.E. Lewis, and J.S. Eisen From cells to circuits: development of the zebrafish spinal cord Prog Neurobiol 69 2003 419 449 This is an outstanding review of the factors controlling determination and the early development in the zebrafish spinal cord.
33. Nissen UV, Mochida H, Glover JC: Development of projection-specific interneurons and projection neurons in the embryonic mouse and rat spinal cord. C Comp Neurol 2004, in press. This is a careful description of the development of spinal cord interneurons in rats and mice using classical anatomical and immunocytochemical methods.
34. S.J. Butt, and O. Kiehn Functional identification of interneurons responsible for left-right coordination of hindlimbs in mammals Neuron 38 2003 953 963 In this study, the authors subdivide a population of descending commissural interneurons into four functionally different classes on the basis of their synaptic actions on motor neurons. The authors go on to study the action of each of these classes during fictive motor patterns and suggest some hypotheses about their roles in the organization of locomotion.
35. S.J. Butt, R.M. Harris-Warrick, and O. Kiehn Firing properties of identified interneuron populations in the mammalian hindlimb central pattern generator J Neurosci 22 2002 9961 9971
36. A. Birinyi, K. Viszokay, I. Weber, O. Kiehn, and M. Antal Synaptic targets of commissural interneurons in the lumbar spinal cord of neonatal rats J Comp Neurol 461 2003 429 440
37. S.R. Kadison, and Z. Kaprielian Diversity of contralateral commissural projections in the embryonic rodent spinal cord J Comp Neurol 472 2004 411 422
38. P. Szucs, F. Odeh, K. Szokol, and M. Antal Neurons with distinctive firing patterns, morphology and distribution in laminae V-VII of the neonatal rat lumbar spinal cord Eur J Neurosci 17 2003 537 544
39. J.S. Dasen, J.P. Liu, and T.M. Jessell Motor neuron columnar fate imposed by sequential phases of Hox-c activity Nature 425 2003 926 933
40. S. Sockanathan, T. Perlmann, and T.M. Jessell Retinoid receptor signaling in postmitotic motor neurons regulates rostrocaudal positional identity and axonal projection pattern Neuron 40 2003 97 111 In this study, the authors show that retinoid receptor activation is important in specifying motor neuron subtypes. This suggests a regionally restricted role for retinoid signaling.
41. B.G. Novitch, H. Wichterle, T.M. Jessell, and S. Sockanathan A requirement for retinoic acid-mediated transcriptional activation in ventral neural patterning and motor neuron specification Neuron 40 2003 81 95 In this study, the authors investigate the roles of retinoid signaling in neuronal specification in the ventral spinal cord.
42. C.M. William, and Y. Tanabe Jessell TM: Regulation of motor neuron subtype identity by repressor activity of Mnx class homeodomain proteins Development 130 2003 1523 1536
43. F. Helmbacher, E. Dessaud, S. Arber, O. deLapeyriere, C.E. Henderson, R. Klein, and F. Maina Met signaling is required for recruitment of motor neurons to PEA3-positive motor pools Neuron 39 2003 767 777
44. A.W. Lin, and E.M. Carpenter Hoxa10 and Hoxd10 coordinately regulate lumbar motor neuron patterning J Neurobiol 56 2003 328 337
45. O. Kiehn, and K. Kullander Central pattern generators deciphered by molecular genetics Neuron 41 2004 317 321 An excellent review of new advances in the use of genetic and molecular tools to understand the organization of mammalian central pattern generating networks.
46. G.M. Lanuza, S. Gosgnach, A. Pierani, T.M. Jessell, and M. Goulding Genetic identification of spinal interneurons that coordinate left-right locomotor activity necessary for walking movements Neuron 42 2004 375 386 A subset of commissural spinal interneurons express the homeobox gene Dbx1. Mutant mice without these ventral interneurons do not show normal patterns of left-right alternation, suggesting that these neurons are part of the central pattern generating circuit in normal locomotion.
47. T. Sapir, E.J. Geiman, Z. Wang, T. Velasquez, S. Mitsui, Y. Yoshihara, E. Frank, F.J. Alvarez, and M. Goulding Pax6 and Engrailed 1 regulate two distinct aspects of Renshaw cell development J Neurosci 24 2004 1255 1264 In this study, the authors provide evidence that a subset of V1 interneurons become Renshaw cells, one of the best-defined populations of spinal cord interneurons. Pax6 (paired box gene 6) is required for early Renshaw cell development, and Engrailed 1 (En1) is important for synapse formation between Renshaw cells and motor neurons.
48. J, although non-functional Lmx1a is correctly expressed at E8.5-E9.5, it disappears by E10.5. As it does, Bmp expression fails, and the generation and differentiation of the dorsal-most spinal cord interneurons is abnormal.
49. S. Higashijima, M.A. Masino, G. Mandel, and J.R. Fetcho Engrailed-1 expression marks a primitive class of inhibitory spinal interneuron J Neurosci 24 2004 5827 5839 This study demonstrates the utility (in some cases) of transcription factors for cell identification in the zebrafish spinal cord. Engrailed-1 expression marks a class of ascending interneurons, called circumferential ascending (CiA) interneurons that express the glycine transporter 2 gene. The CiA neurons are rhythmically active during swimming and make monosynaptic connections with other neurons. Individual Engrailed-1-positive cells function in both sensory gating and motor pattern generation.
50. J.P. Thaler, S.J. Koo, A. Kania, K. Lettieri, S. Andrews, C. Cox, T.M. Jessell, and S.L. Pfaff A postmitotic role for Isl-class LIM homeodomain proteins in the assignment of visceral spinal motor neuron identity Neuron 41 2004 337 350
51. J.M. Weimann, and E. Marder Switching neurons are integral members of multiple oscillatory networks Curr Biol 4 1994 896 902
52. J.P. Miller, and A.I. Selverston Mechanisms underlying pattern generation in lobster stomatogastric ganglion as determined by selective inactivation of identified neurons. IV. Network properties of pyloric system J Neurophysiol 48 1982 1416 1432
53. K. Kullander, S.J. Butt, J.M. Lebret, L. Lundfald, C.E. Restrepo, A. Rydstrom, R. Klein, and O. Kiehn Role of EphA4 and EphrinB3 in local neuronal circuits that control walking Science 299 2003 1889 1892 In this study, the authors characterize the motor patterns generated by mice lacking either ephrinB3 or the EphA4 receptor. Isolated spinal cords from newborn mice were studied. Bilateral ventral roots displayed an abnormal synchronous rhythm instead of the normal left-right alternation seen in wild type mice of the same age. Left-right alternation is supposed to be mediated by commissural interneurons that cross the midline. In the mutant mice additional fibers were seen to cross the midline, suggesting that these aberrant connections were responsible, at least in part, for the abnormal motor patterns.
54. M.E. Hale, M.A. Kheirbek, J.E. Schriefer, and V.E. Prince Hox gene misexpression and cell-specific lesions reveal functionality of homeotically transformed neurons J Neurosci 24 2004 3070 3076 The authors asked whether or not ectopic Mauthner cells made by manipulations of the Hox genes could integrate into spinal circuitry and participate in the escape response of larval zebrafish. Using calcium imaging the authors found that the homeotically transformed neurons responded to startle stimuli and that lesions of the normal Mauthner cells did not decrease escape performance when the ectopic cells were present. From these data the authors suggest that the incorporation of functionally redundant neurons into circuits could provide a substrate for circuit evolution.
55. b420 mutants were active during an escape response and that the escape response in mutant larvae was similar to that in wild type fish. The authors argue that excess Mauthner cells are incorporated into the escape-response circuit in such a way to produce a normal response.
56. J.C. Caldwell, M.M. Miller, S. Wing, D.R. Soll, and D.F. Eberl Dynamic analysis of larval locomotion in Drosophila chordotonal organ mutants Proc Natl Acad Sci USA 100 2003 16053 16058 Mutants lacking chordotonal organs show altered larval movements, similar to those generated in animals lacking almost all sensory neurons, suggesting that the chordotonal organs play a major part in the production of normal larval movements.
57. M. Landgraf, V. Jeffrey, M. Fujioka, J.B. Jaynes, and M. Bate Embryonic origins of a motor system: motor dendrites form a myotopic map in Drosophila PLoS Biol 1 2003 E41 The authors present a description of the development of the structure of motor dendrites in the larval Drosophila.
58. M.L. Suster, J.R. Martin, C. Sung, and S. Robinow Targeted expression of tetanus toxin reveals sets of neurons involved in larval locomotion in Drosophila J Neurobiol 55 2003 233 246 In this study, the authors blocked transmitter release from defined populations of larval Drosophila neurons using targeted tetanus toxin expression. Expression of toxin in dopaminergic and serotonergic neurons altered turning.
59. J.C. Choi, D. Park, and L.C. Griffith Electrophysiological and morphological characterization of identified motor neurons in the Drosophila third instar larva central nervous system J Neurophysiol 91 2004 2353 2365 The authors used genetic methods to express green fluorescent protein (GFP) in subsets of neurons, and then electrophysiological recordings and dye-fills of individual neurons were made. This is an important paper because it is one of the first to obtain voltage clamp recordings from identified neurons in the fly.
60. J.A. Ainsley, J.M. Pettus, D. Bosenko, C.E. Gerstein, N. Zinkevich, M.G. Anderson, C.M. Adams, M.J. Welsh, and W.A. Johnson Enhanced locomotion caused by loss of the Drosophila DEG/ENaC protein Pickpocket1 Curr Biol 13 2003 1557 1563 Pickpocket1 (PPK1) is a Drosophila subunit of the epithelial sodium channel (ENaC) that is found in dendritic (md) sensory neurons in the larval body wall and in some bipolar neurons in the brain. ppk1 null mutant larvae showed normal touch sensation and md neuron morphology but altered crawling.
61. V.S. Fénelon, Y. Le Feuvre, and P. Meyrand Phylogenetic, ontogenetic and adult adaptive plasticity of rhythmic neural networks: a common neuromodulatory mechanism? J Comp Physiol A Neuroethol Sens Neural Behav Physiol 190 2004 691 705 The authors present a comprehensive review of the development of the stomatogastric nervous system and compare it with other preparations.
62. V.S. Fénelon, V. Kilman, P. Meyrand, and E. Marder Sequential developmental acquisition of neuromodulatory inputs to a central pattern-generating network J Comp Neurol 408 1999 335 351
63. V.L. Kilman, V. Fénelon, K.S. Richards, V. Thirumalai, P. Meyrand, and E. Marder Sequential developmental acquisition of cotransmitters in identified sensory neurons of the stomatogastric nervous system of the lobsters, Homarus americanus and Homarus gammarus J Comp Neurol 408 1999 318 334
64. Y. Le Feuvre, V.S. Fénelon, and P. Meyrand Ontogeny of modulatory inputs to motor networks: early established projection and progressive neurotransmitter acquisition J Neurosci 21 2001 1313 1326
65. S.R. Pulver, V. Thirumalai, K.S. Richards, and E. Marder Dopamine and histamine in the developing stomatogastric system of the lobster Homarus americanus J Comp Neurol 462 2003 400 414
66. K.S. Richards, and E. Marder The actions of crustacean cardioactive peptide on adult and developing stomatogastric ganglion motor patterns J Neurobiol 44 2000 31 44
67. S.D. Merrywest, J.R. McDearmid, O. Kjaerulff, O. Kiehn, and K.T. Sillar Mechanisms underlying the noradrenergic modulation of longitudinal coordination during swimming in Xenopus laevis tadpoles Eur J Neurosci 17 2003 1013 1022
68. S.A. Pearson, A. Mouihate, Q.J. Pittman, and P.J. Whelan Peptidergic activation of locomotor pattern generators in the neonatal spinal cord J Neurosci 23 2003 10154 10163
69. M.A. Madriaga, L.C. McPhee, T. Chersa, K.J. Christie, and P.J. Whelan Modulation of locomotor activity by multiple 5-HT and dopaminergic receptor subtypes in the neonatal mouse spinal cord J Neurophysiol 92 2004 1566 1576
70. E. Brustein, M. Chong, B. Holmqvist, and P. Drapeau Serotonin patterns locomotor network activity in the developing zebrafish by modulating quiescent periods J Neurobiol 57 2003 303 322
71. D.L. McLean, and K.T. Sillar Divergent actions of serotonin receptor activation during fictive swimming in frog embryos J Comp Physiol A Neuroethol Sens Neural Behav Physiol 190 2004 391 402
72. P. Branchereau, J. Chapron, and P. Meyrand Descending 5-hydroxytryptamine raphe inputs repress the expression of serotonergic neurons and slow the maturation of inhibitory systems in mouse embryonic spinal cord J Neurosci 22 2002 2598 2606
73. J.R. Cazalets, M. Gardette, and G. Hilaire Locomotor network maturation is transiently delayed in the MAOA- deficient mouse J Neurophysiol 83 2000 2468 2470
74. Y.Q. Ding, U. Marklund, W. Yuan, J. Yin, L. Wegman, J. Ericson, E. Deneris, R.L. Johnson, and Z.F. Chen Lmx1b is essential for the development of serotonergic neurons Nat Neurosci 6 2003 933 938 This is a study of the mechanisms that influence the development of serotonin neurons in the raphe nuclei in mice. A LIM homeodomain-containing gene Lmx1b, is required for the development of the neurons that contain 5-HT.
75. J.C. Viemari, H. Burnet, M. Bevengut, and G. Hilaire Perinatal maturation of the mouse respiratory rhythm-generator: in vivo and in vitro studies Eur J Neurosci 17 2003 1233 1244 This study shows that two days before birth mice are unable to survive when surgically delivered despite the fact that slice preparations from these animals indicate that respiratory rhythms can be produced. These slice preparations respond differently from those from older animals.
76. J.C. Smith, H.H. Ellenberger, K. Ballanyi, D.W. Richter, and J.L. Feldman Pre-Bötzinger complex: a brainstem region that may generate respiratory rhythm in mammals Science 254 1991 726 729
77. P.A. Gray, W.A. Janczewski, N. Mellen, D.R. McCrimmon, and J.L. Feldman Normal breathing requires preBotzinger complex neurokinin-1 receptor-expressing neurons Nat Neurosci 4 2001 927 930
78. B. Blanchi, L.M. Kelly, J.C. Viemari, I. Lafon, H. Burnet, M. Bevengut, S. Tillmanns, L. Daniel, T. Graf, and G. Hilaire MafB deficiency causes defective respiratory rhythmogenesis and fatal central apnea at birth Nat Neurosci 6 2003 1091 1100 Mice deficient for the transcription factor MafB die at birth and slices made from these animals show altered respiratory rhythms. MafB is expressed in neurons found in the preBötzC, suggesting that proper formation of the preBötzC requires MafB action.
79. J.C. Viemari, M. Bevengut, H. Burnet, P. Coulon, J.M. Pequignot, M.C. Tiveron, and G. Hilaire Phox2a gene, A6 neurons, and noradrenaline are essential for development of normal respiratory rhythm in mice J Neurosci 24 2004 928 937 The Phox2a gene encodes a homeodomain protein required for the development of noradrenergic A6 neurons. Mice fetuses mutant for this gene had impaired in vivo ventilation, and slices from these animals showed alterations in respiratory rhythms and responses to hypoxia and norepinephrine. Treatments with the adrenergic antagonist prazosin produced effects similar to those shown in the mutants. These data are interpreted to mean that normal development requires noradrenergic inputs at the appropriate time.
80. C. Consoulas, C. Duch, R.J. Bayline, and R.B. Levine Behavioral transformations during metamorphosis: remodeling of neural and motor systems Brain Res Bull 53 2000 571 583
81. J.C. Weeks Thinking globally, acting locally: steroid hormone regulation of the dendritic architecture, synaptic connectivity and death of an individual neuron Prog Neurobiol 70 2003 421 442 An excellent review of steroid reconfiguration of the nervous system in Manduca sexta.
82. S. Hebbar, and J.J. Fernandes Pruning of motor neuron branches establishes the DLM innervation pattern in Drosophila J Neurobiol 60 2004 499 516 In Drosophila, larval muscles are replaced by adult muscles at metamorphosis. In this study, the authors describe the dorsal longitudinal muscle (DLM) innervation pattern through metamorphosis in wild type and in flies carrying several mutations.
83. C. Duch, and T. Mentel Stage-specific activity patterns affect motoneuron axonal retraction and outgrowth during the metamorphosis of Manduca sexta Eur J Neurosci 17 2003 945 962 During metamorphosis many larval muscles and sensory neurons are replaced, but many motor neurons persist and are remodeled in the adult. In Manduca sexta, the formation of adult dorsal longitudinal flight muscle is accompanied by retraction of the axonal terminals and dendrites of the larval motor neurons, muscle degeneration, and myoblast accumulation. These structural changes have been attributed to steroid action. This study investigates whether or not activity-dependent mechanisms are also important. Precociously simulating the motor neurons with ecdysis-like patterns resulted in growth of their terminals, suggesting that steroids might act together with activity-dependent mechanisms during postembryonic alterations at the neuromuscular junction.
84. J.R. Gray, and J.C. Weeks Steroid-induced dendritic regression reduces anatomical contacts between neurons during synaptic weakening and the developmental loss of a behavior J Neurosci 23 2003 1406 1415 Steroid hormones influence neuronal structure in many preparations. In larvae of Manduca sexta, each abdominal proleg has an array of mechanosensory hairs that are innervated by a planta hair sensory neuron. Planta hair sensory neurons elicit monosynaptic excitatory post-synaptic potentials (EPSPs) onto accessory planta retractor motor neurons that mediate a withdrawal reflex behavior that is lost when the animal pupates. An ecdysteriod prepupal peak triggers the regression of motor neuron dendrites and a large reduction in the amplitude of EPSPs evoked by planta hair sensory neurons. The authors conclude that steroid-induced regression of motor neuron dendrites physically disconnects the sensory neurons and the motor neurons, resulting in the loss of the proleg withdrawal reflex.
85. C. Duch, and T. Mentel Activity affects dendritic shape and synapse elimination during steroid controlled dendritic retraction in Manduca sexta J Neurosci 24 2004 9826 9837 In this study, the authors demonstrate that enhanced electrical activity of the MN5 neuron decreases dendritic regression and loss of synaptic connections normally triggered by steroids. The authors suggest that activity can modify otherwise rigidly defined hormonally triggered developmental sequences.
86. D. Combes, S.D. Merrywest, J. Simmers, and K.T. Sillar Developmental segregation of spinal networks driving axial- and hindlimb-based locomotion in metamorphosing Xenopus laevis J Physiol 559 2004 17 24 This is a remarkable study describing the motor patterns produced in Xenopus as swimming tadpoles make the transition from axial-based swimming to limbed propulsion. During this switch the larval and adult motor systems function in the same animal. The authors of this study developed isolated preparations of the spinal cord and brainstem at varying times during these transitions. Extracellular ventral root recordings from the spinal cord of pre-metamorphic tadpoles showed motor patterns corresponding to larval axial swimming. Older, postmetamorphic animals expressed bilaterally synchronous hindlimb flexion-extension kicks. In vitro recordings from stages in which the tail and the limbs are both functional showed two distinct motor patterns, corresponding to bipedal extension-flexion cycles and larval-like swimming. The authors take these data to indicate that during metamorphosis separate networks coexist in the spinal cord and remain functional after isolation in vitro, thus enabling the opportunity to study changes in the nervous system required to adapt to changes in body plan.
87. C. Straus, R.J. Wilson, and J.E. Remmers Developmental disinhibition: turning off inhibition turns on breathing in vertebrates J Neurobiol 45 2000 75 83
88. D.R. Bentley, and R.R. Hoy Postembryonic development of adult motor patterns in crickets: a neural analysis Science 170 1970 1409 1411
89. R.E. Winmill, and M.S. Hedrick Gap junction blockade with carbenoxolone differentially affects fictive breathing in larval and adult bullfrogs Respir Physiol Neurobiol 138 2003 239 251