The Calyx of Held Develops Adult-Like Dynamics and Reliability by Hearing Onset in the Mouse<i>In Vivo</i>

Sonntag, Mandy; Englitz, Bernhard; Typlt, Marei; Rübsamen, Rudolf

doi:10.1523/jneurosci.0575-11.2011

Cited by 47 publications

(61 citation statements)

References 41 publications

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“…We initially determined whether the mechanisms of PTP are developmentally regulated by comparing the properties of synaptic plasticity before (P8-10) and after (P16-19) the onset of hearing (~P12) (Sonntag et al, 2009; Sonntag et al, 2011). A widely-used approach to assess whether changes in p contribute to changes in neurotransmitter release is to determine whether synaptic changes are accompanied by alterations in the paired-pulse ratio (PPR) of two closely spaced stimuli.…”

Section: Resultsmentioning

confidence: 99%

Calcium-Dependent PKC Isoforms Have Specialized Roles in Short-Term Synaptic Plasticity

Chu

Fioravante

Leitges

et al. 2014

Neuron

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Summary Post-tetanic potentiation (PTP) is a widely observed form of short-term plasticity lasting for tens of seconds after high-frequency stimulation. Here we show that although protein kinase C (PKC) mediates PTP at the calyx of Held synapse in the auditory brainstem before and after hearing onset, PTP is produced primarily by an increased probability of release (p) before hearing onset, and by an increased readily-releasable pool of vesicles (RRP) thereafter. We find that these mechanistic differences, which have distinct functional consequences, reflect unexpected differential actions of closely related calcium-dependent PKC isoforms. Prior to hearing onset, when PKCγ and PKCβ are both present, PKCγ mediates PTP by increasing p and partially suppressing PKCβ actions. After hearing onset, PKCγ is absent and PKCβ produces PTP by increasing RRP. In hearing animals, virally expressed PKCγ overrides PKCβ to produce PTP by increasing p. Thus, two similar PKC isoforms mediate PTP in distinctly different ways.

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Section: Resultsmentioning

confidence: 99%

Calcium-Dependent PKC Isoforms Have Specialized Roles in Short-Term Synaptic Plasticity

Chu

Fioravante

Leitges

et al. 2014

Neuron

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“…We examined glial marker expression at P14, after the period of hearing onset (Mikaelian et al, 1965, Sonntag et al, 2011). Synaptic function and structure change at this stage as the calyx of Held matures.…”

Section: Discussionmentioning

confidence: 99%

Distribution of glial cells in the auditory brainstem: Normal development and effects of unilateral lesion

et al. 2014

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Auditory brainstem networks facilitate sound source localization through binaural integration. A key component of this circuitry is the projection from the ventral cochlear nucleus (VCN) to the medial nucleus of the trapezoid body (MNTB), a relay nucleus that provides inhibition to the superior olivary complex. This strictly contralateral projection terminates in the large calyx of Held synapse. The formation of this pathway requires spatiotemporal coordination of cues that promote cell maturation, axon growth, and synaptogenesis. Here we have examined the emergence of distinct classes of glial cells, which are known to function in development and in response to injury. Immunofluorescence for several astrocyte markers revealed unique expression patterns. ALDH1L1 was expressed earliest in both nuclei, followed by S100β, during the first postnatal week. GFAP expression was seen in the second postnatal week. GFAP-positive cell bodies remained outside the boundaries of VCN and MNTB, with a limited number of labeled fibers penetrating into the margins of the nuclei. OLIG2 expression revealed the presence of oligodendrocytes in VCN and MNTB from birth until after hearing onset. In addition, IBA1-positive microglia were observed after the first postnatal week. Following hearing onset, all glial populations were found in MNTB. We then determined the distribution of glial cells following early (P2) unilateral cochlear removal, which results in formation of ectopic projections from the intact VCN to ipsilateral MNTB. We found that following perturbation, astrocytic markers showed expression near the ectopic ipsilateral calyx. Taken together, the developmental expression patterns are consistent with a role for glial cells in the maturation of the calyx of Held and suggest that these cells may have a similar role in maturation of lesion-induced connections.

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“…Also the SBCs of the AVCN were identified by the complex waveform of the recorded discharges (Pfeiffer, 1966;Winter et al, 1990;Englitz et al, 2009;Typlt et al, 2010) and/or by the primary-like PSTH (Blackburn and Sachs, 1989). The accurate analysis of the complex waveforms was done using a fitting method, which decomposes the extracellularly recorded signal into its presynaptic and postsynaptic components (Sonntag et al, 2011). However, due to the smaller size of the prepotential signal in the AVCN than in MNTB, and the higher noise susceptibility in recordings with multibarrel electrodes, the fitting method could be applied only to a limited number of recordings.…”

Section: In Vivo Recordingsmentioning

confidence: 99%

Purinergic Modulation of Neuronal Activity in Developing Auditory Brainstem

Dietz

Jovanovic²,

Wielsch³

et al. 2012

Journal of Neuroscience

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In the developing nervous system, spontaneous neuronal activity arises independently of experience or any environmental input. This activity may play a major role in axonal pathfinding, refinement of topographic maps, dendritic morphogenesis, and the segregation of axonal terminal arbors. In the auditory system, endogenously released ATP in the cochlea activates inner hair cells to trigger bursts of action potentials (APs), which are transferred to the central auditory system. Here we show the modulatory role of purinergic signaling beyond the cochlea, i.e., the developmentally regulated and cell-type-specific depolarizing effects on auditory brainstem neurons of Mongolian gerbil. We assessed the effects of P2X receptors (P2XRs) on neuronal excitability from prehearing to early stages of auditory signal processing. Our results demonstrate that in neurons expressing P2XRs, extracellular ATP can evoke APs in sync with Ca 2ϩ signals. In cochlear nucleus (CN) bushy cells, ATP increases spontaneous and also acoustically evoked activity in vivo, but these effects diminish with maturity. Moreover, ATP not only augmented glutamate-driven firing, but it also evoked APs in the absence of glutamatergic transmission. In vivo recordings also revealed that endogenously released ATP in the CN contributes to neuronal firing activity by facilitating AP generation and prolonging AP duration. Given the enhancing effect of ATP on AP firing and confinement of P2XRs to certain auditory brainstem nuclei, and to distinct neurons within these nuclei, it is conceivable that purinergic signaling plays a specific role in the development of neuronal brainstem circuits.

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The Calyx of Held Develops Adult-Like Dynamics and Reliability by Hearing Onset in the MouseIn Vivo

Cited by 47 publications

References 41 publications

Calcium-Dependent PKC Isoforms Have Specialized Roles in Short-Term Synaptic Plasticity

Calcium-Dependent PKC Isoforms Have Specialized Roles in Short-Term Synaptic Plasticity

Distribution of glial cells in the auditory brainstem: Normal development and effects of unilateral lesion

Purinergic Modulation of Neuronal Activity in Developing Auditory Brainstem

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