Synaptogenesis of the Calyx of Held: Rapid Onset of Function and One-to-One Morphological Innervation

Synaptogenesis during early development is thought to follow a canonical program whereby synapses increase rapidly in number and individual axons multiply-innervate nearby targets. Typically, a subset of inputs then out-competes all others through experience-driven processes to establish stable, long-lasting contacts. We investigated the formation of the calyx of Held, probably the largest nerve terminal in the mammalian CNS. Many basic functional and morphological features of calyx growth have not been studied previously, including whether mono-innervation, a hallmark of this system in adult animals, is established early in development. Evoked postsynaptic currents, recorded from neonatal mice between postnatal day 1 (P1) and P4, increased dramatically from −0.14 ± 0.04 nA at P1 to −6.71 ± 0.65 nA at P4 with sharp jumps between P2 and P4. These are the first functional assays of these nascent synapses for ages less than P3. AMPA and NMDA receptor-mediated currents were prominent across this age range. Electron microscopy (EM) revealed a concomitant increase, beginning at P2, in the prevalence of postsynaptic densities (16-fold) and adhering contacts (73-fold) by P4. Therefore, both functional and structural data showed that young calyces could form within 2 d, well before the onset of hearing around P8. Convergence of developing calyces onto postsynaptic targets, indicative of competitive processes that precede mono-innervation, was rare (4 of 29) at P4 as assessed using minimal stimulation electrophysiology protocols. Serial EM sectioning through 19 P4 cells further established the paucity (2 of 19) of convergence. These data indicate that calyces of Held follow a noncanonical program to establish targeted innervation that occurs over a rapid time course and precedes auditory experience.

[1]  J. Borst,et al.  Branching of calyceal afferents during postnatal development in the rat auditory brainstem , 2006, The Journal of comparative neurology.

[2]  David A DiGregorio,et al.  Changes in synaptic structure underlie the developmental speeding of AMPA receptor–mediated EPSCs , 2005, Nature Neuroscience.

[3]  G. Ehret Infant Rodent Ultrasounds – A Gate to the Understanding of Sound Communication , 2005, Behavior genetics.

[4]  Jeff W. Lichtman,et al.  Axon Branch Removal at Developing Synapses by Axosome Shedding , 2004, Neuron.

[5]  V. Wimmer,et al.  Targeted in vivo expression of proteins in the calyx of Held , 2004, Pflügers Archiv.

[6]  D. McCormick,et al.  Multiple large inputs to principal cells in the mouse medial nucleus of the trapezoid body. , 2004, Journal of neurophysiology.

[7]  C. Sotelo,et al.  Cellular and genetic regulation of the development of the cerebellar system , 2004, Progress in Neurobiology.

[8]  F. Lang,et al.  Channel-induced apoptosis of infected host cells—the case of malaria , 2004, Pflügers Archiv.

[9]  D. K. Morest,et al.  The growth of synaptic endings in the mammalian brain: A study of the calyces of the trapezoid body , 1968, Zeitschrift für Anatomie und Entwicklungsgeschichte.

[10]  E. Friauf,et al.  Principal cells of the rat medial nucleus of the trapezoid body: an intracellular in vivo study of their physiology and morphology , 2004, Experimental Brain Research.

[11]  E. Friauf,et al.  Divergent projections of physiologically characterized rat ventral cochlear nucleus neurons as shown by intra-axonal injection of horseradish peroxidase , 2004, Experimental Brain Research.

[12]  N. Kasthuri,et al.  The role of neuronal identity in synaptic competition , 2003, Nature.

[13]  J. Sanes,et al.  Watching the neuromuscular junction , 2003, Journal of neurocytology.

[14]  N. Ziv,et al.  Unitary Assembly of Presynaptic Active Zones from Piccolo-Bassoon Transport Vesicles , 2003, Neuron.

[15]  J. Lichtman,et al.  In Vivo Time-Lapse Imaging of Synaptic Takeover Associated with Naturally Occurring Synapse Elimination , 2003, Neuron.

[16]  G. Spirou,et al.  Optimizing Synaptic Architecture and Efficiency for High-Frequency Transmission , 2002, Neuron.

[17]  Bert Sakmann,et al.  Three-Dimensional Reconstruction of a Calyx of Held and Its Postsynaptic Principal Neuron in the Medial Nucleus of the Trapezoid Body , 2002, The Journal of Neuroscience.

[18]  B. Billups,et al.  Detecting synaptic connections in the medial nucleus of the trapezoid body using calcium imaging , 2002, Pflügers Archiv.

[19]  Lu-Yang Wang,et al.  Developmental profiles of glutamate receptors and synaptic transmission at a single synapse in the mouse auditory brainstem , 2002, The Journal of physiology.

[20]  Bernd Fritzsch,et al.  Auditory system development: primary auditory neurons and their targets. , 2002, Annual review of neuroscience.

[21]  T. Moser,et al.  The Presynaptic Function of Mouse Cochlear Inner Hair Cells during Development of Hearing , 2001, The Journal of Neuroscience.

[22]  K. Futai,et al.  High-Fidelity Transmission Acquired via a Developmental Decrease in NMDA Receptor Expression at an Auditory Synapse , 2001, The Journal of Neuroscience.

[23]  Eckart D. Gundelfinger,et al.  Assembling the Presynaptic Active Zone A Characterization of an Active Zone Precursor Vesicle , 2001, Neuron.

[24]  G. Spirou,et al.  Specialized Synapse-Associated Structures within the Calyx of Held , 2000, The Journal of Neuroscience.

[25]  H. von Gersdorff,et al.  Fine-Tuning an Auditory Synapse for Speed and Fidelity: Developmental Changes in Presynaptic Waveform, EPSC Kinetics, and Synaptic Plasticity , 2000, The Journal of Neuroscience.

[26]  Charles J. Limb,et al.  Development of Primary Axosomatic Endings in the Anteroventral Cochlear Nucleus of Mice , 2000, Journal of the Association for Research in Otolaryngology.

[27]  A. Hall,et al.  Axonal Remodeling and Synaptic Differentiation in the Cerebellum Is Regulated by WNT-7a Signaling , 2000, Cell.

[28]  G. Spirou,et al.  PEP-19 immunoreactivity in the cochlear nucleus and superior olive of the cat , 1998, Neuroscience.

[29]  Mnh,et al.  Histologie du Système Nerveux de Lʼhomme et des Vertébrés , 1998 .

[30]  G. Spirou,et al.  Glycine immunoreactivity in the lateral nucleus of the trapezoid body of the cat. , 1997, The Journal of comparative neurology.

[31]  I. Forsythe,et al.  Pre‐ and postsynaptic glutamate receptors at a giant excitatory synapse in rat auditory brainstem slices. , 1995, The Journal of physiology.

[32]  M. Semple,et al.  Development of ventral cochlear nucleus projections to the superior olivary complex in gerbil , 1995, The Journal of comparative neurology.

[33]  I. Forsythe,et al.  The binaural auditory pathway: excitatory amino acid receptors mediate dual timecourse excitatory postsynaptic currents in the rat medial nucleus of the trapezoid body , 1993, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[34]  E. Friauf,et al.  Pre‐ and postnatal development of efferent connections of the cochlear nucleus in the rat , 1993, The Journal of comparative neurology.

[35]  J. Lichtman,et al.  In vivo observations of pre- and postsynaptic changes during the transition from multiple to single innervation at developing neuromuscular junctions , 1993, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[36]  J. Zook,et al.  Afferents to the medial nucleus of the trapezoid body and their collateral projections , 1991, The Journal of comparative neurology.

[37]  Philip H Smith,et al.  Projections of physiologically characterized globular bushy cell axons from the cochlear nucleus of the cat , 1991, The Journal of comparative neurology.

[38]  J. Jansen,et al.  The perinatal reorganization of the innervation of skeletal muscle in mammals , 1990, Progress in Neurobiology.

[39]  G. Spirou,et al.  Recordings from cat trapezoid body and HRP labeling of globular bushy cell axons. , 1990, Journal of neurophysiology.

[40]  James E. Vaughn,et al.  Review: Fine structure of synaptogenesis in the vertebrate central nervous system , 1989 .

[41]  J. E. Vaughn,et al.  Fine structure of synaptogenesis in the vertebrate central nervous system. , 1989, Synapse.

[42]  R. Semba,et al.  Glycine-like immunoreactivity in the rat auditory pathway , 1988, Brain Research.

[43]  J. McGee,et al.  Postnatal development of auditory nerve and cochlear nucleus neuronal responses in kittens , 1987, Hearing Research.

[44]  Donata Oertel,et al.  Maturation of synapses and electrical properties of cells in the cochlear nuclei , 1987, Hearing Research.

[45]  J. Aran,et al.  Glycine immunoreactivity in the brainstem auditory and vestibular nuclei of the guinea pig. , 1987, Acta oto-laryngologica.

[46]  E Eldred,et al.  Maximal force as a function of anatomical features of motor units in the cat tibialis anterior. , 1987, Journal of neurophysiology.

[47]  M. Geffard,et al.  Glycine neurons in the brain and spinal cord. Antibody production and immunocytochemical localization , 1986, Brain Research.

[48]  J. Eggermont Evoked potentials as indicators of auditory maturation. , 1985, Acta oto-laryngologica. Supplementum.

[49]  D. K. Morest,et al.  The neuronal architecture of the anteroventral cochlear nucleus of the cat in the region of the cochlear nerve root: Electron microscopy , 1982, Neuroscience.

[50]  D. Yurgelun-Todd,et al.  The neuronal architecture of the anteroventral cochlear nucleus of the cat in the region of the cochlear nerve root: Horseradish peroxidase labelling of identified cell types , 1982, Neuroscience.

[51]  T. Parks,et al.  Functional synapse elimination in the developing avian cochlear nucleus with simultaneous reduction in cochlear nerve axon branching , 1982, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[52]  S. Jhaveri,et al.  Sequential alterations of neuronal architecture in nucleus magnocellularis of the developing chicken: An electron microscope study , 1982, Neuroscience.

[53]  Nell B. Cant,et al.  The bushy cells in the anteroventral cochlear nucleus of the cat. A study with the electron microscope , 1979, Neuroscience.

[54]  F. Crépel,et al.  Evidence for a multiple innervation of Purkinje cells by climbing fibers in the immature rat cerebellum. , 1976, Journal of neurobiology.

[55]  R. Oppenheim,et al.  Some aspects of synaptogenesis in the spinal cord of the chick embryo: A quantitative electron microscopic study , 1975, The Journal of comparative neurology.

[56]  Viktor Hamburger,et al.  Fine structure of dendritic and axonal growth cones in embryonic chick spinal cord , 1974, The Journal of comparative neurology.

[57]  W. Warr Fiber degeneration following lesions in the multipolar and globular cell areas in the ventral cochlear nucleus of the cat. , 1972, Brain research.

[58]  D. K. Morest,et al.  The collateral system of the medial nucleus of the trapezoid body of the cat, its neuronal architecture and relation to the olivo-cochlear bundle. , 1968, Brain research.

[59]  B. Lane,et al.  DIFFERENTIAL STAINING OF ULTRATHN SECTIONS OF EPON-EMBEDDED TISSUES FOR LIGHT MICROSCOPY , 1965, The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society.

[60]  R. Ruben,et al.  Development of Hearing in the Normal Cba-J Mouse: Correlation of Physiological Observations with Behavioral Responses and with Cochlear Anatomy , 1965 .