Glutamatergic connections of the auditory midbrain: Selective uptake and axonal transport of D-[3H]aspartate

Marie, Richard L. Saint

doi:10.1002/(sici)1096-9861(19960916)373:2<255::aid-cne8>3.0.co;2-2

Cited by 111 publications

(47 citation statements)

References 69 publications

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“…3), individual IC neurons receive ascending inputs from several different brainstem nuclei (Oliver and Shneiderman, 1991;Roth et al, 1978), some of which are excitatory and some of which are inhibitory (Burger and Pollak, 2001;Li and Kelly, 1992;Saint Marie, 1996;Saint Marie and Baker, 1990). Small spiral ganglion lesions produce CF shifts and other unexpected changes in the shapes of IC frequency tuning curves that could not occur in peripheral neurons, demonstrating that IC neurons integrate frequency information in a complex way (Snyder and Sinex, 2002).…”

Section: B What Accounts For Differences Between An Fiber and Ic Dismentioning

confidence: 64%

Spectral Processing and Sound Source Determination

Sinex

2005

International Review of Neurobiology

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Humans normally listen in mixed environments, in which sounds originating from more than one source overlap in time and in frequency. The auditory system is able to extract information specific to the individual sources that contribute to the composite signal and process the information for each source separately; this is called "auditory scene analysis" or "sound-source determination." Sounds that are simultaneously present but generated independently tend to differ along relatively simple acoustic dimensions. These dimensions may be temporal, as when sounds begin or end asynchronously, or spectral, as when the sounds have different fundamental frequencies. Psychophysical experiments have identified some of the ways in which human listeners use these dimensions to isolate sources of sound. A simple but useful stimulus, a harmonic complex tone with or without a mistuned component, can be used for parametric investigation of the processing of spectral structure. This "mistuned tone" stimulus has been used in several psychophysical experiments, and more recently in studies that specifically address the neural mechanisms that underlie segregation based on harmonicity. Studies of the responses of single neurons in the chinchilla auditory system to mistuned tones are reviewed here in detail. The results of those experiments support the view that neurons in the inferior colliculus (IC) exhibit responses to mistuned tones that are larger and temporally more complex than the same neurons' responses to harmonic tones. Mistuning does not produce comparable changes in the discharge patterns of auditory nerve (AN) fibers, indicating that a major transformation in the neural representation of harmonic structure occurs in the auditory brainstem. The brainstem processing that accomplishes this transformation may contribute to the segregation of competing sounds and ultimately to the identification of sound sources.

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Section: B What Accounts For Differences Between An Fiber and Ic Dismentioning

confidence: 64%

Spectral Processing and Sound Source Determination

Sinex

2005

International Review of Neurobiology

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“…Previous data support the role of glutamate as the main excitatory neurotransmitter in the inferior colliculus (Faingold, 2002;Caicedo and Eybalin, 1999;Feliciano and Potashner, 1995;Gaza and Ribak, 1997;Goldsmith et al, 1995;Helfert et al, 1999;Liao et al, 2000;Moore et al, 1998;Parks, 2000;Saint Marie, 1996;Suneja et al, 1995Suneja et al, , 2000. In addition, glutamine and glutamate have numerous functions in different organs working as precursors for neurotransmitters, related proteins, nucleotides, nucleic acids and glutathione synthesis.…”

Section: Introductionmentioning

confidence: 68%

Glutamate-related gene expression changes with age in the mouse auditory midbrain

et al. 2007

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Glutamate is the main excitatory neurotransmitter in both the peripheral and central auditory systems. Changes of glutamate and glutamate-related genes with age may be an important factor in the pathogenesis of age-related hearing loss -presbycusis. In this study, changes in glutamate-related mRNA gene expression in the CBA mouse inferior colliculus with age and hearing loss were examined and correlations were sought between these changes and functional hearing measures, such as the auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs). Gene expression of 68 glutamate-related genes was investigated using both genechip microarray and real-time PCR (qPCR) molecular techniques for four different age/hearing loss CBA mouse subject groups. Two genes showed consistent differences between groups for both the genechip and qPCR. Pyrroline-5-carboxylate synthetase enzyme (Pycs) showed down-regulation with age and a highaffinity glutamate transporter (Slc1a3) showed up-regulation with age and hearing loss. Since Pycs plays a role in converting glutamate to proline, its deficiency in old age may lead to both glutamate increases and proline deficiencies in the auditory midbrain, playing a role in the subsequent inducement of glutamate toxicity and loss of proline neuroprotective effects. The up-regulation of Slc1a3 gene expression may reflect a cellular compensatory mechanism to protect against age-related glutamate or calcium excitoxicity.

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“…In addition, some projections from the periolivary nuclei are also immunonegative for both glycine and GABA (Ostapoff et al 1997). Finally, projections from the inferior colliculus may be glutamatergic and excitatory (Saint Marie 1996).…”

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

confidence: 99%

“…DAVIS 1996;Arnott et al 2004). Figure 7 shows the effects on representative type IV units of pharmacological and surgical manipulations of the dorsal fiber tracts at two locations.…”

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confidence: 99%

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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Glutamatergic connections of the auditory midbrain: Selective uptake and axonal transport of D-[3H]aspartate

Cited by 111 publications

References 69 publications

Spectral Processing and Sound Source Determination

Spectral Processing and Sound Source Determination

Glutamate-related gene expression changes with age in the mouse auditory midbrain

Contralateral Effects and Binaural Interactions in Dorsal Cochlear Nucleus

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