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Eckhard Friauf - One of the best experts on this subject based on the ideXlab platform.
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Electrical Membrane Properties of Trapezoid Body Neurons in the Rat Auditory Brain Stem Are Preserved in Organotypic Slice Cultures
2020Co-Authors: Martin Kungel, Eckhard FriaufAbstract:The Superior Olivary Complex (SOC) is the first convert this information to an inhibitory, glycinergic input to the ipsilateral LSO. LSO neurons station in the mammalian auditory brain stem where input from both ears converges and binaural inforalso receive excitatory, glutamatergic inputs emerging from neurons in the ipsilateral cochlear nucleus. mation is analyzed. Among other nuclei, the SOC Thus, they compute intensity differences occurring includes the medial nucleus of the trapezoid body at the two ears and are involved in the localization (MNTB) and the lateral Superior olive (LSO). of sound sources (Irvine, 1986). The SOC nuclei MNTB neurons receive excitatory, glutamatergic show a precise topographical organization of both input from the contralateral cochlear nucleus and the excitatory and the inhibitory connections, which is why this brain area serves as a suitable system Correspondence to: S. Löhrke to study the development of these two types of con
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Development of Glycinergic and Glutamatergic Synaptic Transmission in the Auditory Brainstem of Perinatal Rats
2013Co-Authors: Karl K, Eckhard FriaufAbstract:In contrast to our knowledge about the anatomical development of the mammalian central auditory system, the development of its physiological properties is still poorly understood. In order to better understand the physiological properties of the developing mammalian auditory brainstem, we made intracellular recordings in brainstem slices from perinatal rats to examine synaptic transmission in the Superior Olivary Complex, the first binaural station in the ascending auditory pathway. We concentrated on neurons in the lateral Superior olive (LSO), which in adults, are excited from the ipsilateral side and inhibited from the contralateral side. Already at embryonic day (E) 18, when axon collaterals begin to invade the LSO anlage, synaptic potentials could be evoked from ipsilateral, as well as from contralateral inputs. lpsilaterally elicited PSPs were always depolarizing
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ª Federation of European Neuroscience Societies Gene expression profiling of the rat Superior Olivary Complex using serial analysis of gene expression
2013Co-Authors: Er Koehl, Eckhard Friauf, Nicole Schmidt, Anne Rieger, Sara M. Pilgram, Ivica Letunic, Peer Bork, Florentina Soto, Hans Gerd NothwangAbstract:The Superior Olivary Complex (SOC) is an auditory brainstem region that represents a favourable system to study rapid neurotransmission and the maturation of neuronal circuits. Here we performed serial analysis of gene expression (SAGE) on the SOC in 60-day-old Sprague–Dawley rats to identify genes specifically important for its function and to create a transcriptome reference for the subsequent identification of age-related or disease-related changes. Sequencing of 31 035 tags identified 10 473 different transcripts. Fifty-seven per cent of the unique tags with a count greater than four were statistically more highly represented in the SOC than in the hippocampus. Among them were genes encoding proteins involved in energy supply, the glutamate ⁄ glutamine shuttle, and myelination. Approximately 80 plasma membrane transporters, receptors, channels, and vesicular transporters were identified, and 25 % of them displayed a significantly higher expression level in the SOC than in the hippocampus. Some of the plasma membrane proteins were not previously characterized in the SOC, e.g. the purinergic receptor subunit P2X6 and the metabotropic GABA receptor Gpr51. Differential gene expression between SOC and hippocampus was confirmed using RNA in situ hybridization or immunohistochemistry. The extensive gene inventory presented here will alleviate the dissection of the molecular mechanisms underlying specific SOC functions and the comparison with other SAGE libraries from brain will ease the identification of promoters to generate region-specific transgenic animals. The analysis will be part of the publicly available database ID-GRAB
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electrical membrane properties of trapezoid body neurons in the rat auditory brain stem are preserved in organotypic slice cultures
Journal of Neurobiology, 1998Co-Authors: Stefan Löhrke, Martin Kungel, Eckhard FriaufAbstract:The medial nucleus of the trapezoid body (MNTB) is a conspicuous structure in the mammalian auditory brain stem. It is a major component of the Superior Olivary Complex and is involved in sound localization. Recently, organotypic slice culture preparations of the Superior Olivary Complex were introduced to investigate the development of inhibitory and excitatory projections (Sanes and Hafidi, 1996; Lohmann et al., 1998). In the present article, we further assessed the organotypicity of our culture system (Lohmann et al., 1998) and examined electrical membrane properties of MNTB neurons expressed under culture conditions. To do so, MNTB neurons from early postnatal rats (P3–5) were studied after 3–6 days in vitro (DIV) by whole-cell patch-clamp recordings. Their mean resting potential was −59 mV, the input resistance averaged 171 MΩ, and the average time constant was 3 ms. Four types of voltage-activated conductances were observed in voltage-clamp recordings. All cells expressed a tetrodotoxin (TTX)-sensitive sodium current. Two types of potassium currents could be characterized: a tetraethylammonium (TEA)-sensitive and a 4-aminopyridine (4-AP)-sensitive conductance, both of which are composed of a transient and a sustained component. Finally, an inwardly rectifying current, activated by hyperpolarizing voltage steps, was found. In current-clamp recordings, depolarizing current pulses typically elicited a single action potential. In the presence of 4-AP, however, these current pulses induced a train of action potentials. The duration of action potentials was increased by 4-AP and the afterhyperpolarization was reduced. Hyperpolarizing current injections induced a “sag” in the membrane potential, indicating the influence of an inwardly rectifying current. Our results demonstrate that MNTB neurons in slice cultures have electrical membrane properties comparable to those of their counterparts in acute slices. © 1998 John Wiley & Sons, Inc. J Neurobiol 36: 395–409, 1998
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distribution of the calcium binding proteins parvalbumin and calretinin in the auditory brainstem of adult and developing rats
The Journal of Comparative Neurology, 1996Co-Authors: Christian Lohmann, Eckhard FriaufAbstract:Parvalbumin (PV), calretinin (CR), and calbindin (CB) are calcium-binding proteins which are presumably involved in the regulation of the intracellular calcium concentration. Within the rat auditory system, CB is transiently expressed in several nuclei during the period of synapse refinement, indicating a specific function of CB during development, yet little is known in this regard about PV and CR. In order to gather more information about calcium-binding proteins during development, we analyzed the spatiotemporal distribution of PV and CR in the rat auditory brainstem using immunocytochemistry. In the adult, PV was heavily present in somata and neuropil of all nuclei and in fibers of all tracts. CR was found in somata of the cochlear nucleus and peripheral aspects of the inferior colliculus as well as in fibers extending into the Superior Olivary Complex and the nuclei of the lateral lemniscus. The developmental expression of PV was characterized by a relatively late appearance in somata (at postnatal day 8), followed by a rapid increase to adult levels. In contrast, CR immunoreactivity was already strong two days before birth, yet the number and intensity of labeled neurons subsequently decreased and CR disappeared almost completely in the Superior Olivary Complex, nuclei of the lateral lemniscus, and central aspects of the inferior colliculus. These data, together with those on CB, show that CR, CB, and PV are sequentially expressed during auditory brainstem development. They also suggest that the presence of the three proteins can be correlated with definite developmental stages. © 1996 Wiley-Liss, Inc.
Brett R Schofield - One of the best experts on this subject based on the ideXlab platform.
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Multiple Sources of Cholinergic Input to the Superior Olivary Complex
'Frontiers Media SA', 2021Co-Authors: Brett R Schofield, Nichole L. Beebe, Chao Zhang, Michael R. BurgerAbstract:The Superior Olivary Complex (SOC) is a major computation center in the brainstem auditory system. Despite previous reports of high expression levels of cholinergic receptors in the SOC, few studies have addressed the functional role of acetylcholine in the region. The source of the cholinergic innervation is unknown for all but one of the nuclei of the SOC, limiting our understanding of cholinergic modulation. The medial nucleus of the trapezoid body, a key inhibitory link in monaural and binaural circuits, receives cholinergic input from other SOC nuclei and also from the pontomesencephalic tegmentum. Here, we investigate whether these same regions are sources of cholinergic input to other SOC nuclei. We also investigate whether individual cholinergic cells can send collateral projections bilaterally (i.e., into both SOCs), as has been shown at other levels of the subcortical auditory system. We injected retrograde tract tracers into the SOC in gerbils, then identified retrogradely-labeled cells that were also immunolabeled for choline acetyltransferase, a marker for cholinergic cells. We found that both the SOC and the pontomesencephalic tegmentum (PMT) send cholinergic projections into the SOC, and these projections appear to innervate all major SOC nuclei. We also observed a small cholinergic projection into the SOC from the lateral paragigantocellular nucleus of the reticular formation. These various sources likely serve different functions; e.g., the PMT has been associated with things such as arousal and sensory gating whereas the SOC may provide feedback more closely tuned to specific auditory stimuli. Further, individual cholinergic neurons in each of these regions can send branching projections into both SOCs. Such projections present an opportunity for cholinergic modulation to be coordinated across the auditory brainstem
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cholinergic cells of the pontomesencephalic tegmentum connections with auditory structures from cochlear nucleus to cortex
Hearing Research, 2011Co-Authors: Brett R Schofield, Susan D Motts, Jeffrey G MellottAbstract:Acetylcholine (ACh) is a neuromodulator that is likely to play a role in plasticity as well as other phenomena at many sites in the auditory system. The auditory cortex receives cholinergic innervation from the basal forebrain, whereas the cochlea receives cholinergic innervation from the Superior Olivary Complex. Much of the remainder of the auditory pathways receives innervation from the pedunculopontine and laterodorsal tegmental nuclei, two nuclei referred to collectively as the pontomesencephalic tegmentum (PMT). The PMT provides the major source of ACh to the auditory thalamus and the midbrain, and is a substantial source (in addition to the Superior Olivary Complex) of ACh in the cochlear nucleus. Individual cholinergic cells in the PMT often have axon branches that innervate multiple auditory nuclei, including nuclei on both sides of the brain as well as nuclei at multiple levels of the auditory system. The auditory cortex has direct axonal projections to the PMT cells, including cholinergic cells that project to the inferior colliculus or cochlear nucleus. The divergent projections of PMT cholinergic cells suggest widespread effects on the auditory pathways. These effects are likely to include plasticity as well as novelty detection, sensory gating, reward behavior, arousal and attention. Descending projections from the forebrain, including the auditory cortex, are likely to provide a high level of cognitive input to these cholinergic effects. Dysfunction associated with the cholinergic system may play a role in disorders such as tinnitus and schizophrenia.
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ascending and descending projections from the Superior Olivary Complex in guinea pigs different cells project to the cochlear nucleus and the inferior colliculus
The Journal of Comparative Neurology, 2002Co-Authors: Brett R SchofieldAbstract:The Superior Olivary Complex is a source of ascending projections to the inferior colliculus and descending projections to the cochlear nucleus. We used multiple-labeling techniques with fluorescent retrograde tracers to determine whether individual Superior Olivary cells project to the inferior colliculus and the cochlear nucleus. Almost all labeled cells contained one tracer, suggesting that they projected to only one of the injected targets. A small number of cells sent collateral projections to the ipsilateral cochlear nucleus and ipsilateral inferior colliculus. The double-labeled cells constituted fewer than 2% of the cells that projected to the cochlear nucleus or to the inferior colliculus. There was no evidence for cells projecting to both contralateral targets or to one ipsilateral target and one contralateral target. We conclude that the ascending projections to the inferior colliculus and the descending projections to the cochlear nucleus arise almost exclusively from separate populations of cells in the Superior Olivary Complex. Their separate origins suggest that these projections are sending different information to higher and lower centers of the auditory pathways. J. Comp. Neurol. 453:217–225, 2002. © 2002 Wiley-Liss, Inc.
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projections to the cochlear nuclei from principal cells in the medial nucleus of the trapezoid body in guinea pigs
The Journal of Comparative Neurology, 1994Co-Authors: Brett R SchofieldAbstract:Spherical and globular cells in the cochlear nucleus provide input to the cell groups in the Superior Olivary Complex devoted to the analysis of binaural cues. Desending projections from the Superior Olivary Complex appear to inhibit the spherical and globular cells. It is not known which of the numerous cell types in the Superior olive provide this descending input, but recent studies have shown that some of the cells are located in the medial nucleus of the trapezoid body (MTB). The present experiments were designed to determine whether the MTB projections arise from principal cells, which are known to play a role sound localization, and to determine whether their projections terminate on spherical or globular cells. Principal cells in the MTB are characterized by their contacts with synaptic specializations called calyces, which arise from the axons of cells in the contralateral cochlear nucleus. In the first experiment, a fluorescent tracer was injected into one cochlear nucleus to label the calyces anterogradely. A dfferent tracer was injected into the opposite cochlear nucleus to label cells retogradely in the MTB. In every case, some of the labeled cells were enveloped by a labeled calyx, demonstrating that principal cells do project to the cochlear nucleus. In the second experiment, fluorescent tracers were injected into different parts of the cochlear nucleus. Anaysis of the distribution of labeled cells suggested that MTB projections selectively target the globular cell region of the cochlear nucleus. In a third experiment, the axonal arborizations arising from this projection were labeled with biocytin or wheat germ agglutinin conjugated to horseradish peroxidase. Labeled boutons appeared to contact globular cels but not spherical cells. Multipolar cells in the ventral cochlear nucleus and cells in the dorsal cochlear nucleus were also contacted. The results suggest that MTB projections to the cochlear nucleus arise largely from principal cells and contact, at least in part, cells in the cochlear nucleus that give rise to ascending pathways involved in sound localization. © 1994 Wiley-Liss, Inc.
Diana I Lurie - One of the best experts on this subject based on the ideXlab platform.
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chronic low level lead exposure affects the monoaminergic system in the mouse Superior Olivary Complex
The Journal of Comparative Neurology, 2009Co-Authors: Tyler Fortune, Diana I LurieAbstract:Low-level lead (Pb) exposure is associated with behavioral and cognitive dysfunction, but it is not clear how Pb produces these behavioral changes. Pb has been shown to alter auditory temporal processing in both humans and animals. Auditory temporal processing occurs in the Superior Olivary Complex (SOC) in the brainstem, where it is an important component in sound detection in noisy environments and in selective auditory attention. The SOC receives a serotonergic innervation from the dorsal raphe, and serotonin has been implicated in auditory temporal processing within the brainstem and inferior colliculus. Because Pb exposure modulates auditory temporal processing, the serotonergic system is a potential target for Pb. The current study was undertaken to determine whether developmental Pb exposure preferentially changes the serotonergic system within the SOC. Pb-treated mice were exposed to no Pb, very low Pb (0.01 mM), or low Pb (0.1 mM) throughout gestation and through 21 days postnatally. Brainstem sections from control and Pb-exposed mice were immunostained for the vesicular monoamine transporter 2 (VMAT2), serotonin (5-HT), and dopamine-beta-hydroxylase (DbetaH; a marker for norepinephrine) in order to elucidate the effect of Pb on monoaminergic input into the SOC. Sections were also immunolabeled with antibodies to vesicular glutamate transporter 1 (VGLUT1), vesicular gamma-aminobutyric acid (GABA) transporter (VGAT), and vesicular acetylcholine transporter (VAChT) to determine whether Pb exposure alters the glutaminergic, GABAergic, or cholinergic systems. Pb exposure caused a significant decrease in VMAT2, 5-HT, and DbetaH expression, whereas VGLUT1, VGAT, and VAChT showed no change. These results provide evidence that Pb exposure during development alters normal monoaminergic expression in the auditory brainstem.
Chiyeko Tsuchitani - One of the best experts on this subject based on the ideXlab platform.
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the brain stem evoked response and medial nucleus of the trapezoid body
Otolaryngology-Head and Neck Surgery, 1994Co-Authors: Chiyeko TsuchitaniAbstract:: Single-unit responses of cat Superior Olivary Complex neurons to acoustic stimuli were examined to determine whether the units' action potentials were sufficiently synchronized to contribute to the brain stem evoked response. The medial nucleus of the trapezoid body and lateral Superior olive are two major nuclei within the cat Superior Olivary Complex. The first-spike discharge latencies of medial nucleus of the trapezoid body and lateral Superior Olivary neurons to monaural presentations of tone burst stimuli were measured as a function of stimulus level. Evidence is provided to support the hypotheses that in cat the medial nucleus of the trapezoid body may contribute directly to the monaural brain stem evoked response by producing action potentials synchronized to stimulus onset and may also contribute indirectly to the brain stem evoked response binaural difference wave bc by inhibiting the lateral Superior olive unit excitatory responses synchronized to stimulus onset.
Leonard M Kitzes - One of the best experts on this subject based on the ideXlab platform.
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development of ventral cochlear nucleus projections to the Superior Olivary Complex in gerbil
The Journal of Comparative Neurology, 1995Co-Authors: Jonathan Kil, Glenn Hkageyama, Malcolm N Semple, Leonard M KitzesAbstract:The postnatal development of the projection from the ventral cochlear nucleus to the principal nuclei in the Superior Olivary Complex in gerbil (Meriones unguiculatus) was studied in an age-graded series of pups ranging from 0 to 18 days old. Small crystals of 1, 1′-dioctadecyl3, 3, 3′, 3′-tetramethylindocarbocyanine perchlorate (DiI) were inserted into the ventral cochlear nucleus of aldehyde-fixed brains, and the labeled projections were examined with epifluorescence microscopy. Selected sections were photooxidized in a solution of diaminobenzidine and subsequently processed for electron microscopy to examine the development of labeled synapses in the target nuclei. Horseradish peroxidase was injected into the ventral cochlear nucleus of adult gerbils to assess the form and persistence of projections observed in the neonatal animals. In addition, electrophysiological responses to acoustic stimuli of single units in the adult auditory brainstem were analyzed to confirm the functionality of the novel projection from the ventral cochlear nucleus to the contralateral lateral Superior olive. By the day of birth (PO), developing axons from the ventral cochlear nucleus have already established highly ordered pathways to the three primary nuclei of the Superior Olivary Complex: the ipsilateral lateral Superior olive, the contralateral medial nucleus of the trapezoid body, and at the lateral and medial dendrites of the ipsilateral and contralateral medial Superior olive, respectively. Developing axons from the ventral cochlear nucleus that innervated the contralateral medial nucleus of the trapezoid body lacked the terminal morphology characteristic of the calyx of Held, but began to adopt a more characteristic form on P5. The mature calyx appeared around P14–16. Exuberant developmental projections to topographically inappropriate areas of the Superior Olivary Complex were not observed at the postnatal ages studied. In addition to the projections of the ventral cochlear nucleus to the Superior Olivary Complex described in other species, we observed the development and maintenance of a major direct projection from the ventral cochlear nucleus to the contralateral lateral Superior olive. On PO, ventral cochlear nucleus axons decussate in the dorsal trapezoid body, form a plexus at the dorsal edge of the contralateral medial Superior olive, and enter the ventrolateral limb of the contralateral lateral Superior olive. Over the next 2 weeks, fascicles of fibers form on the hilar and ventral aspects of the ventrolateral limb. Fibers arising from these fascicles form converging, but nonoverlapping, arborizations within the ventrolateral limb at right angles to the curvature of the nucleus. The medial region was devoid of labeled axons. The direct innervation of the contralateral lateral Superior olive was confirmed in the adult gerbil with anterograde horseradish peroxidase histochemistry and by the recording of excitatory responses in the innervated region to acoustic stimulation of the contralateral ear. © 1995 Wiley-Liss, Inc.
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development of ectopic projections from the ventral cochlear nucleus to the Superior Olivary Complex induced by neonatal ablation of the contralateral cochlea
The Journal of Comparative Neurology, 1995Co-Authors: Leonard M Kitzes, Malcolm N Semple, Glenn H Kageyama, Jonathan KilAbstract:The ability of an animal to localize a sound in space requires the precise innervation of the Superior Olivary Complex by the ventral cochlear nuclei on each side of the lower brainstem. This precise pattern of innervation could require an immutable recognition of appropriate targets by afferent processes arising from these nuclei. This possibility was investigated by destroying one cochlea of gerbil pups (Meriones unguiculatus) on the second postnatal day and assessing the projections from the ventral cochlear nucleus (VCN) on the unablated side to the Superior Olivary Complex during the subsequent 2 weeks and after the animals had reached maturity. A crystal of 1, l′-dioctadecyl-3, 3, 3′, 3′-tetramethylindocarbocyanine perchlorate (DiI) was inserted into VCN on the unablated side in animals ranging in age from 3 to 14 days. To assess the permanence of any altered pattern of innervation, horseradish peroxidase was injected into VCN on the unablated side in adult, neonatally ablated animals. Finally, electrophysiological responses to acoustic stimuli delivered to the ear on the unablated side were recorded in the Superior Olivary Complex of adult animals to assess whether altered innervation patterns were functional. Normative data were derived from our accompanying study of the development of VCN projections to the Superior Olivary Complex in normal gerbils (Kil et al., this issue). Whereas VCN normally projects to the lateral aspect of the ipsilateral medial Superior olive and to the medial aspect of the contralateral medial Superior olive in control animals, in experimental animals VCN on the unablated side projects to both sides of these nuclei. Whereas in the gerbil, VCN normally projects only to the hilar area and to the ventrolateral limb of the contralateral lateral Superior olive, in experimental animals VCN on the unablated side projects throughout this nucleus. This induced projection is specific in that the efferents to each limb of the contralateral nucleus are linked to the normal projection to the homotopic region of the ipsilateral nucleus. Whereas VCN innervates the contralateral medial nucleus of the trapezoid body in control animals, in experimental animals VCN on the unablated side provides calyces of Held in the ipsilateral nucleus as well. The induced projections to these three major subnuclei of the Superior Olivary Complex first appear within 24 hours of the cochlear ablation and continue to develop over at least the subsequent 11 days. Thus, prior to the day when the cochlea becomes functional, VCN has established specific ectopic projections to loci normally innervated by VCN on the ablated side. All induced ectopic projections observed in neonatal animals were also present in neonatally ablated adult animals, indicating their permanence. As in the case of the normal projections from VCN to these subnuclei, all labeled synapses contained round vesicles and formed asymmetric synaptic junctional Complexes with dendrites and somata in these target nuclei. Electrophysiological responses of single units in the ipsilateral medial nucleus of the trapezoid body demonstrated that the induced calyces of Held in this structure are quite functional in adult animals. © 1995 Wiley-Liss, Inc.