Fast Inhibition Underlies the Transmission of Auditory Information between Cochlear Nuclei

Needham, Karina; Paolini, Antonio G.

doi:10.1523/jneurosci.23-15-06357.2003

Cited by 47 publications

(74 citation statements)

References 34 publications

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“…However, other chopper units were inhibited suggesting a dual action of MOC efferents. Third, Needham and Paolini (2003) found that contralateral tones elicited sustained excitatory postsynaptic potentials in chopper units with a delay of 7-10 ms. Similarly, chopper units showed a short-latency membrane hyperpolarization after stimulation of the contralateral ear with noise that was soon exceeded by excitatory inputs (latency of õ14 ms).…”

Section: A Conceptual Model Of Contralateral Inputs To Type IV Unitsmentioning

confidence: 97%

“…Finally, the commissural pathway arises primarily from large multipolar cells in the VCN (Cant and Gaston 1982;Shore et al 1992;Schofield and Cant 1996) that are glycinergic (Wenthold 1987;Ostapoff et al 1997;Alibardi 2000;Babalian et al 2002). Recent studies have shown that at least some of these cells have O c responses to sound (Needham and Paolini 2003;Arnott et al 2004). In addition, it appears from Arnott et al that the axons of O c units travel across the brainstem near the fibers of the IAS.…”

Section: A Conceptual Model Of Contralateral Inputs To Type IV Unitsmentioning

confidence: 99%

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Contralateral Effects and Binaural Interactions in Dorsal Cochlear Nucleus

Davis

2005

JARO

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The dorsal cochlear nucleus (DCN) receives afferent input from the auditory nerve and is thus usually thought of as a monaural nucleus, but it also receives inputs from the contralateral cochlear nucleus as well as descending projections from binaural nuclei. Evidence suggests that some of these commissural and efferent projections are excitatory, whereas others are inhibitory. The goals of this study were to investigate the nature and effects of these inputs in the DCN by measuring DCN principal cell (type IV unit) responses to a variety of contralateral monaural and binaural stimuli. As expected, the results of contralateral stimulation demonstrate a mixture of excitatory and inhibitory influences, although inhibitory effects predominate. Most type IV units are weakly, if at all, inhibited by tones but are strongly inhibited by broadband noise (BBN). The inhibition evoked by BBN is also low threshold and short latency. This inhibition is abolished and excitation is revealed when strychnine, a glycine-receptor antagonist, is applied to the DCN; application of bicuculline, a GABA Areceptor antagonist, has similar effects but does not block the onset of inhibition. Manipulations of discrete fiber bundles suggest that the inhibitory, but not excitatory, inputs to DCN principal cells enter the DCN via its output pathway, and that the short latency inhibition is carried by commissural axons. Consistent with their respective monaural effects, responses to binaural tones as a function of interaural level difference are essentially the same as responses to ipsilateral tones, whereas binaural BBN responses decrease with increasing contralateral level. In comparison to monaural responses, binaural responses to virtual space stimuli show enhanced sensitivity to the elevation of a sound source in ipsilateral space but reduced sensitivity in contralateral space. These results show that the contralateral inputs to the DCN are functionally relevant in natural listening conditions, and that one role of these inputs is to enhance DCN processing of spectral sound localization cues produced by the pinna.

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Section: A Conceptual Model Of Contralateral Inputs To Type IV Unitsmentioning

confidence: 97%

Section: A Conceptual Model Of Contralateral Inputs To Type IV Unitsmentioning

confidence: 99%

Contralateral Effects and Binaural Interactions in Dorsal Cochlear Nucleus

Davis

2005

JARO

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“…Glycinergic inhibition is observed in the cochlear nucleus a few milliseconds after contralateral stimulation (Pfalz 1962;Mast 1970;Young and Brownell 1976;Evans and Zhao 1993;Joris and Smith 1998;Babalian et al 1999Babalian et al , 2002Shore et al 2003;Needham and Paolini 2003;Davis 2005;Ingham et al 2006). Type II neurons are one source of this short-latency binaural interaction (Needham and Paolini 2003;Arnott et al 2004;Smith et al 2005;Needham and Paolini 2006).…”

Section: Functional Considerationsmentioning

confidence: 99%

“…Instead, Type I neurons may contribute to the short-latency excitation that is elicited by contralateral stimulation (Mast 1973;Young and Brownell 1976;Shore et al 2003;Davis 2005;Needham and Paolini 2003;Ingham et al 2006). Such effects are observed less frequently and are of smaller magnitude when compared with Type II inhibition.…”

Section: Functional Considerationsmentioning

confidence: 99%

“…Tract-tracing studies have confirmed that these neurons project to the contralateral cochlear nucleus (Arnott et al 2004;Smith et al 2005;Doucet and Ryugo 2006). Because Type II (D-stellate) neurons are glycinergic (Wenthold 1987;Alibardi, 1998;Doucet et al 1999), they are thought to be a major source of the short-latency inhibition that is observed in the cochlear nucleus after contralateral stimulation (Pfalz 1962;Mast 1970;Young and Brownell 1976;Babalian et al 1999;Needham and Paolini 2003;Shore et al 2003). However, the majority of commissural neurons lack the anatomical features that are characteristic of the Type II morphology (Shore et al 1992;Schofield and Cant 1996b;Alibardi 1998;Doucet and Ryugo 2006).…”

Section: Introductionmentioning

confidence: 97%

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Commissural Neurons in the Rat Ventral Cochlear Nucleus

Doucet

Lenihan

May

2009

JARO

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Commissural neurons connect the cochlear nucleus complexes of both ears. Previous studies have suggested that the neurons may be separated into two anatomical subtypes on the basis of percent apposition (PA); that is, the percentage of the soma apposed by synaptic terminals. The present study combined tract tracing with synaptic immunolabeling to compare the soma area, relative number, and location of Type I (low PA) and Type II (high PA) commissural neurons in the ventral cochlear nucleus (VCN) of rats. Confocal microscopic analysis revealed that 261 of 377 (69%) commissural neurons have mediumsized somata with Type I axosomatic innervation. The commissural neurons also showed distinct topographical distributions. The majority of Type I neurons were located in the small cell cap of the VCN, which serves as a nexus for regulatory pathways within the auditory brainstem. Most Type II neurons were found in the magnocellular core. This anatomical dichotomy should broaden current views on the function of the commissural pathway that stress the fast inhibitory interactions generated by Type II neurons. The more prevalent Type I neurons may underlie slow regulatory influences that enhance binaural processing or the recovery of function after injury.

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Structural and functional classes of multipolar cells in the ventral cochlear nucleus

Doucet

Ryugo

2006

Anat. Rec.

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Multipolar cells in the ventral cochlear nucleus (VCN) are a structurally and functionally diverse group of projection neurons. Understanding their role in the ascending pathway involves partitioning multipolar cells into distinct populations and determining where in the brain each sends its coded messages. In this study, we used retrograde labeling techniques in rats to identify multipolar neurons that project their axons to the ipsilateral dorsal cochlear nucleus (DCN), the contralateral CN, or both structures. Three rats received injections of biotinylated dextran amine in the ipsilateral DCN and diamidino yellow in the contralateral CN. Several radiate multipolar neurons (defined by their axonal projections to the ipsilateral DCN and their dendrites that traverse VCN isofrequency sheets) were double-labeled but over 70% were not. This result suggests two distinct populations: (1) radiate-commissural (RC) multipolar cells that project to the ipsilateral DCN and the contralateral CN, and (2) radiate multipolar cells that project exclusively (in this context) to the ipsilateral DCN. In a different group of animals, we retrogradely labeled multipolar neurons that project their axons to the contralateral CN and measured the size of their cell bodies. The mean size of this population (266 Ϯ 156 m 2 ) was significantly smaller than those of RC-multipolar cells (418 Ϯ 140 m 2 ). We conclude that the CN commissural pathway is composed of at least two components: (1) RC multipolar cells and (2) commissural multipolar cells that are small-and medium-sized neurons that project exclusively (in this context) to the contralateral CN. These results identify separate structural groups of multipolar cells that may correspond to physiological unit types described in the literature. They also provide protocols for isolating and studying different populations of multipolar cells to determine the neural mechanisms that govern their responses to sound. Anat Rec Part 288A:331-344, 2006. Key words: hearing; ascending pathways; classifying neurons; naming neuronsInformation about sound is conveyed to the brain by patterns of action potentials in the auditory nerve. These patterns are analyzed first by neurons in the cochlear nucleus (CN) that are the source of all ascending pathways in the central auditory system. An important step toward understanding the neural circuits that underlie hearing is to define how CN neurons divide, select, and encode the enormous amount of acoustic information that they receive.Dendritic morphology can be used to partition ventral cochlear nucleus (VCN) projection neurons into three groups: bushy, multipolar, and octopus. Octopus cells are located in the caudal pole of the VCN and they are distinguished by several long dendrites that extend from one side of the cell body. Bushy cells usually have one or two primary dendrites. Shortly after arising from the soma, each primary dendrite ends in a spray of thinner and

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Fast Inhibition Underlies the Transmission of Auditory Information between Cochlear Nuclei

Cited by 47 publications

References 34 publications

Contralateral Effects and Binaural Interactions in Dorsal Cochlear Nucleus

Contralateral Effects and Binaural Interactions in Dorsal Cochlear Nucleus

Commissural Neurons in the Rat Ventral Cochlear Nucleus

Structural and functional classes of multipolar cells in the ventral cochlear nucleus

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