A Short-Latency Labyrinthine Input to the Vestibular Nuclei in the Pigeon

Wilson, Victor J.; Wylie, Richard M.

doi:10.1126/science.168.3927.124

Cited by 39 publications

(11 citation statements)

References 10 publications

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“…On the other hand, the avian ciliary ganglion contains large axosomatic endings which disappear at about 6 months [5]. That the calyx starts to break up into small terminals at I week and is completed by I year in the pigeon rests on circumstantial evidence '...th a t the largest masses of frag ments, now [one and six year old pigeons] boutons, are frequently accumulated at one pole of the cell in a location formerly oc cupied by the calyx' [5], Electrophysiological studies of units in the region of the tangential nucleus of the pigeon suggest electrical coupling of second order vestibular neurons and vestibular afferenls [17]. The precise identification of these units as principal cells and spoon endings has not been made.…”

Section: Discussionmentioning

confidence: 99%

Developmental Changes of Synaptic Endings in the Nucleus Vestibularis Tangentialis of the Chicken: Degeneration of Spoon Endings

Peusner¹

1980

Dev Neurosci

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The tangential nucleus. a component of the avian lateral vestibular complex, contains a unique class of very large, axosomatic endings, the spoon endings, formed en passant by the largest vestibular afferents, the colossal fibers. In the hatchling, these endings are characterized by numerous gap junctions, attachment plaques, and a few synaptic vesicle complexes on the principal cell. Spoon endings undergo drastic structural modifications between hatching and 21 months of age in the normal chicken. The spoon endings and their characteristic junctions disappear. However, colossal fibers and principal cells do not degenerate or even atrophy. Synapses are formed by small terminals of unidentified origin on the vacated surfaces of the principal cell bodies. It is concluded that a specific type of synaptic ending may atrophy and degenerate in the normal, young adult brain without the loss of target cells or fibers of origin.

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Section: Discussionmentioning

confidence: 99%

Developmental Changes of Synaptic Endings in the Nucleus Vestibularis Tangentialis of the Chicken: Degeneration of Spoon Endings

Peusner¹

1980

Dev Neurosci

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“…The second is an EPSP mediated by NMDA (N-methyl-D-aspartate) neceptons, which is of almost comparable kinetics to the remaining, considerably larger non-NMDA component. Electrical transmission between the vestibular nerve and secondary neurons occurs in birds (Wilson and Wylie 1970;Peusner and Giaume 1994) and may occur in rodents (Wylie 1973). Both NMDA and non-NMDA chemical transmission between these structures is seen in rodents (Kinney et al 1994;Takahashi et al 1994).…”

Section: Central Mechanisms Central Terminations Of Vestibular-nerve mentioning

confidence: 99%

Afferent diversity and the organization of central vestibular pathways

2000

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This review considers whether the vestibular system includes separate populations of sensory axons innervating individual organs and giving rise to distinct central pathways. There is a variability in the discharge properties of afferents supplying each organ. Discharge regularity provides a marker for this diversity since fibers which differ in this way also differ in many other properties. Postspike recovery of excitability determines the discharge regularity of an afferent and its sensitivity to depolarizing inputs. Sensitivity is small in regularly discharging afferents and large in irregularly discharging afferents. The enhanced sensitivity of irregular fibers explains their larger responses to sensory inputs, to efferent activation, and to externally applied galvanic currents, but not their distinctive response dynamics. Morphophysiological studies show that regular and irregular afferents innervate overlapping regions of the vestibular nuclei. Intracellular recordings of EPSPs reveal that some secondary vestibular neurons receive a restricted input from regular or irregular afferents, but that most such neurons receive a mixed input from both kinds of afferents. Anodal currents delivered to the labyrinth can result in a selective and reversible silencing of irregular afferents. Such a functional ablation can provide estimates of the relative contributions of regular and irregular inputs to a central neuron's discharge. From such estimates it is concluded that secondary neurons need not resemble their afferent inputs in discharge regularity or response dynamics. Several suggestions are made as to the potentially distinctive contributions made by regular and irregular afferents: (1) Reflecting their response dynamics, regular and irregular afferents could compensate for differences in the dynamic loads of various reflexes or of individual reflexes in different parts of their frequency range; (2) The gating of irregular inputs to secondary VOR neurons could modify the operation of reflexes under varying behavioral circumstances; (3) Two-dimensional sensitivity can arise from the convergence onto secondary neurons of otolith inputs differing in their directional properties and response dynamics; (4) Calyx afferents have relatively low gains when compared with irregular dimorphic afferents. This could serve to expand the stimulus range over which the response of calyx afferents remains linear, while at the same time preserving the other features peculiar to irregular afferents. Among those features are phasic response dynamics and large responses to efferent activation; (5) Because of the convergence of several afferents onto each secondary neuron, information transmission to the latter depends on the gain of individual afferents, but not on their discharge regularity.

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“…Similar observations have been made in the vestibular nuclei or their anatomical equivalent in lower vertebrates, including lamprey (Stefanelli and Caravita, 1970), goldfish (Hinojosa, 1973), toadfish (Korn et al, 1977), frog (Sotelo, 1977) and chick (Hinojosa and Robertson, 1967; Peusner, 1984). The terminals forming gap junctions in these species as well as in rat are either known or have been inferred to be of primary afferent origin based on demonstrations of electrical transmission by vestibular primary afferents in toadfish (Korn et al, 1977), frog (Precht et al, 1974; Babalian and Shapovalov, 1984), lizard (Richter et al, 1975), pigeon (Wilson and Wylie, 1970) and rat (Wylie, 1973). Nearly four decades after these early studies, mixed synapses in vestibular nuclei have received little attention, although glutamatergic transmission by primary afferents in these nuclei have been well studied (Highstein and Holstein, 2006).…”

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confidence: 99%

Morphologically mixed chemical–electrical synapses formed by primary afferents in rodent vestibular nuclei as revealed by immunofluorescence detection of connexin36 and vesicular glutamate transporter-1

et al. 2013

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Axon terminals forming mixed chemical/electrical synapses in the lateral vestibular nucleus of rat were described over forty years ago. Because gap junctions formed by connexins are the morphological correlate of electrical synapses, and with demonstrations of widespread expression of the gap junction protein connexin36 (Cx36) in neurons, we investigated the distribution and cellular localization of electrical synapses in the adult and developing rodent vestibular nuclear complex, using immunofluorescence detection of Cx36 as a marker for these synapses. In addition, we examined Cx36 localization in relation to that of the nerve terminal marker vesicular glutamate transporter-1 (vglut-1). An abundance of immunolabelling for Cx36 in the form of Cx36-puncta was found in each of the four major vestibular nuclei of adult rat and mouse. Immunolabelling was associated with somata and initial dendrites of medium and large neurons, and was absent in vestibular nuclei of Cx36 knockout mice. Cx36-puncta were seen either dispersed or aggregated into clusters on the surface of neurons, and were never found to occur intracellularly. Nearly all Cx36-puncta were localized to large nerve terminals immunolabelled for vglut-1. These terminals and their associated Cx36-puncta were substantially depleted after labyrinthectomy. Developmentally, labelling for Cx36 was already present in the vestibular nuclei at postnatal day 5, where it was only partially co-localized with vglut-1, and did not become fully associated with vglut-1-positive terminals until postnatal day 20 to 25. The results show that vglut-1-positive primary afferent nerve terminals form mixed synapses throughout the vestibular nuclear complex, that the gap junction component of these synapses contain Cx36, that multiple Cx36-containing gap junctions are associated with individual vglut-1 terminals and that the development of these mixed synapses is protracted over several postnatal weeks.

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A Short-Latency Labyrinthine Input to the Vestibular Nuclei in the Pigeon

Cited by 39 publications

References 10 publications

Developmental Changes of Synaptic Endings in the Nucleus Vestibularis Tangentialis of the Chicken: Degeneration of Spoon Endings

Developmental Changes of Synaptic Endings in the Nucleus Vestibularis Tangentialis of the Chicken: Degeneration of Spoon Endings

Afferent diversity and the organization of central vestibular pathways

Morphologically mixed chemical–electrical synapses formed by primary afferents in rodent vestibular nuclei as revealed by immunofluorescence detection of connexin36 and vesicular glutamate transporter-1

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