Central projections of auditory nerve fibers in the barn owl

Carr, Catherine; Boudreau, R. E.

doi:10.1002/cne.903140208

Cited by 87 publications

(82 citation statements)

References 55 publications

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“…Timing and intensity cues are processed in separate ascending pathways beginning with the cochlear nuclei Konishi 1978a, 1978b;Konishi et al 1985Konishi et al , 1988Moiseff and Konishi 1983;Sullivan and Konishi 1984;Takahashi et al 1984). The avian cochlear nuclei, NM and NA, receive information from the auditory nerve (Boord and Rasmussen 1963;Carr and Boudreau 1991;Häusler et al 1999;Krützfeldt et al 2010b;Parks and Rubel 1978;Puelles et al 2007;Soares and Carr 2001). NM specializes in encoding fine timing cues and projects to the binaural nucleus responsible for computing ITD, NL (Carr and Konishi 1990;Fukui et al 2006;Hackett et al 1982;Koyano et al 1996;Nishino et al 2008;Raman et al 1994;Reyes et al 1994;Smith 1981;Trussell 1999;Zhang and Trussell 1994).…”

Section: Calretinin and Parallel Processing For Sound Localizationmentioning

confidence: 99%

“…The two anatomically distinct cochlear nuclei, nucleus magnocellularis (NM) and nucleus angularis (NA), each receive information from the auditory nerve and specialize for encoding timing information (NM) and intensity, or sound level, information (NA) for the computation of sound location (Boord 1968;Carr and Boudreau 1991;Parks and Rubel 1978;Puelles et al 2007;Reyes et al 1994;Sullivan and Konishi 1984;Trussell 1999). Nucleus angularis is highly heterogeneous in terms of neuronal morphology, acoustic response types in vivo and intrinsic physiology in vitro, and has multiple ascending projections, suggesting that it performs multiple functions Fukui and Ohmori 2003;Häusler et al 1999;Krützfeldt et al 2010a;MacLeod and Carr 2007;Sachs and Sinnott 1978;Sato et al 2010;Soares and Carr 2001;Soares et al 2002;Wang and Karten 2010;Warchol and Dallos 1990).…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous Calretinin Expression in the Avian Cochlear Nucleus Angularis

Bloom

Williams

MacLeod

2014

JARO

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Multiple calcium-binding proteins (CaBPs) are expressed at high levels and in complementary patterns in the auditory pathways of birds, mammals, and other vertebrates, but whether specific members of the CaBP family can be used to identify neuronal subpopulations is unclear. We used double immunofluorescence labeling of calretinin (CR) in combination with neuronal markers to investigate the distribution of CR-expressing neurons in brainstem sections of the cochlear nucleus in the chicken (Gallus gallus domesticus). While CR was homogeneously expressed in cochlear nucleus magnocellularis, CR expression was highly heterogeneous in cochlear nucleus angularis (NA), a nucleus with diverse cell types analogous in function to neurons in the mammalian ventral cochlear nucleus. To quantify the distribution of CR in the total NA cell population, we used antibodies against neuronal nuclear protein (NeuN), a postmitotic neuronspecific nuclear marker. In NA neurons, NeuN label was variably localized to the cell nucleus and the cytoplasm, and the intensity of NeuN immunoreactivity was inversely correlated with the intensity of CR immunoreactivity. The percentage of CR+neurons in NA increased from 31 % in embryonic (E)17/18 chicks, to 44 % around hatching (E21), to 51 % in postnatal day (P) 8 chicks. By P8, the distribution of CR + neurons was uniform, both rostrocaudal and in the tonotopic (dorsoventral) axis.Immunoreactivity for the voltage-gated potassium ion channel Kv1.1, used as a marker for physiological type, showed broad and heterogeneous postsynaptic expression in NA, but did not correlate with CR expression. These results suggest that CR may define a subpopulation of neurons within nucleus angularis.

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Section: Calretinin and Parallel Processing For Sound Localizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heterogeneous Calretinin Expression in the Avian Cochlear Nucleus Angularis

Bloom

Williams

MacLeod

2014

JARO

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“…In the bird, auditory nerve afferents divide into two with one branch to the nucleus angularis, and the other branch to the nucleus magnocellularis [17,113]. In mammals, similar cell types receiving auditory nerve input are contained in a single nucleus, the ventral cochlear nucleus (see [98]).…”

Section: Presynaptic Specializations For Encoding Temporal Informationmentioning

confidence: 99%

“…In mammals, similar cell types receiving auditory nerve input are contained in a single nucleus, the ventral cochlear nucleus (see [98]). The termination of the auditory nerve onto the cell bodies of avian magnocellularis neurons and mammalian bushy cells takes the form of a specialized calyceal or endbulb terminal while avian NA neurons and mammalian stellate cells are contacted through bouton-like synapses [10,17,26,45,97]. The endbulb terminals envelop the postsynaptic cell body and are characterized by numerous release sites [75,101].…”

Section: Presynaptic Specializations For Encoding Temporal Informationmentioning

confidence: 99%

Coding interaural time differences at low best frequencies in the barn owl

Carr

Köppl

2004

Journal of Physiology-Paris

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In birds and mammals, precisely timed spikes encode the timing of acoustic stimuli, and interaural acoustic disparities propagate to binaural processing centers. The Jeffress model proposes that these projections act as delay lines to innervate an array of coincidence detectors, every element of which has a different relative delay between its ipsilateral and contralateral excitatory inputs. Thus, interaural time difference (ITD) is encoded into the position of the coincidence detector whose delay lines best cancel out the acoustic ITD. Neurons of the avian nucleus laminaris and mammalian MSO phase-lock to both monaural and binaural stimuli but respond maximally when phase-locked spikes from each side arrive simultaneously, i.e. when the difference in the conduction delays compensates for the ITD. McAlpine et al. [Nat. Neurosci. 4 (2001) 396] identified an apparent difference between avian and mammalian ITD coding. In the barn owl, the maximum firing rate appears to encode ITD. This may not be the case for the guinea pig, where the steepest region of the function relating discharge rate to interaural time delay (ITD) is close to midline for all neurons, irrespective of best frequency (BF). These data suggest that low BF ITD sensitivity in the guinea pig is mediated by detection of a change in slope of the ITD function, and not by maximum rate. We review coding of low best frequency ITDs in barn owls and mammals and discuss whether there may be differences in the code used to signal ITD in mammals and birds.

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“…ANF terminals in NM neurons form large end-bulbs of Held (Parks and Rubel, 1978;Whitehead and Morest, 1981;Jhaveri and Morest, 1982a,b,c), and each neuron receives only one to four such inputs (Hackett et al, 1982;Carr and Boudreau, 1991). However, in the barn owl, ANFs are reported to form bouton-like terminals in the low CF (lower than 0.64 kHz) region (Köppl, 1994).…”

Section: Introductionmentioning

confidence: 99%

Tonotopic Gradients of Membrane and Synaptic Properties for Neurons of the Chicken Nucleus Magnocellularis

Fukui¹,

Ohmori²

2004

J. Neurosci.

144

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Nucleus magnocellularis (NM) is a division of the avian cochlear nucleus that extracts the timing of auditory signals. We compared the membrane excitability and synaptic transmission along the tonotopic axis of NM. Neurons expressed a Kv1.1 potassium channel mRNA and protein predominantly in the high characteristic frequency (CF) region of NM. In contrast, the expression of Kv1.2 mRNA did not change tonotopically. Neurons also showed tonotopic gradients in resting potential, spike threshold, amplitude, and membrane rectification. All neurons were sensitive to 100 nM dendrotoxin, but the effects were most significant in the high CF neurons. The EPSC recorded by minimal stimulation of auditory nerve fibers (ANFs) was 13 times larger in high CF neurons than in low CF neurons. Moreover, EPSCs were generated in an all-or-none manner in the high CF neurons when stimulus intensity was increased, whereas EPSCs were graded in the low CF neurons, indicating multiple axonal inputs. ANF synaptic terminals were visualized by DiI. ANF formed enfolding end-bulbs of Held around the cell body in the high and middle CF region but not in the low CF region. These observations indicate coordinated gradients of neuronal properties both presynaptically and postsynaptically along the tonotopic axis. Such specializations may be suitable for extracting and preserving the timing information of auditory signals over a wide range of acoustic frequencies.

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Central projections of auditory nerve fibers in the barn owl

Cited by 87 publications

References 55 publications

Heterogeneous Calretinin Expression in the Avian Cochlear Nucleus Angularis

Heterogeneous Calretinin Expression in the Avian Cochlear Nucleus Angularis

Coding interaural time differences at low best frequencies in the barn owl

Tonotopic Gradients of Membrane and Synaptic Properties for Neurons of the Chicken Nucleus Magnocellularis

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