Sequential alterations of neuronal architecture in nucleus magnocellularis of the developing chicken: A golgi study

Jhaveri, Sonal; Morest, D. Kent

doi:10.1016/0306-4522(82)90046-x

Cited by 190 publications

(104 citation statements)

References 29 publications

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“…Appropriate specializations include minimal cable distortion as a result of somatic innervation, and short membrane time constants (Oertel, 1983;Rothman et al, 1993) both of which are features of the neurons of the nMAG (Jhaveri and Morest, 1982;Zhang and Trussell, unpublished observations). At the level of the synapse, the release of transmitter and the response ofthe postsynaptic cells must preserve the temporal structure of signals.…”

Section: Channel Conductances and Open Timesmentioning

confidence: 99%

“…Cochlear ganglion (CC) cells, which are contacted by hair cells of the cochlea, constitute the sole output of the cochlea. Their projections form the auditory nerve and innervate two brainstem nuclei, nMAG and nANG (Parks and Rubel, 1978), which are homologous to parts of the mammalian cochlear nuclei (Boord, 1969;Jhaveri and Morest, 1982). The nMAG neurons bilaterally innervate nLAM neurons, which are also in the brainstem (Ramon y Cajal, 1908b;Jhaveri and Morest, 1982;Young and Rubel, 1983).…”

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confidence: 99%

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Pathway-specific variants of AMPA receptors and their contribution to neuronal signaling

1994

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Neurons of the nucleus magnocellularis (nMAG) of the chick express AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate) receptors displaying unusually rapid kinetics of desensitization (Raman and Trussell, 1992a). To investigate whether fast AMPA receptors are present in other auditory neurons, we compared the properties of AMPA receptors in auditory as well as nonauditory cells. These included neurons of nMAG, the nucleus angularis, the nucleus laminaris, the cochlear ganglion, the Purkinje cell layer of the cerebellum, the ventral horn of the spinal cord, and the brainstem nucleus of the glossopharyngeal nerve (ncIX). Rapid application of glutamate to voltage-clamped outside-out membrane patches indicated that AMPA receptors in the four types of auditory cells had significantly faster kinetics of desensitization than did the three types of nonauditory neurons. Channel kinetics in auditory (nMAG) and nonauditory (ncIX) cells were also compared by means of spectral analysis and the time course of current deactivation upon removal of glutamate. Both techniques revealed a burst duration for nMAG channels of 400–500 musec at room temperature, two to three times shorter than for ncIX cells. Single channels in nMAG had a burst duration of 550 musec and an open time of approximately 150 musec. Miniature excitatory postsynaptic currents of brainstem auditory neurons in slices were also brief, with decay constants of 150–250 musec at 29–32 degrees C. We demonstrated that the fast kinetics of this AMPA receptor are physiologically important, since cyclothiazide, which reduces desensitization and prolongs synaptic currents, doubled the relative refractory period of orthodromic spikes in nMAG cells in brain slices. We conclude that auditory brainstem neurons express a specialized subtype of AMPA receptors. This “fast” AMPA receptor may be useful in transmitting signals necessary for sound localization.

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Section: Channel Conductances and Open Timesmentioning

confidence: 99%

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confidence: 99%

Pathway-specific variants of AMPA receptors and their contribution to neuronal signaling

1994

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“…Each collateral branch descends ventrally to form a single endbulb on a NM cell body and the distribution of the endings corresponds to the tonotopic organization of the nucleus [165,201]. Endbulbs are a large calyx-like axosomatic ending formed by auditory nerve fibers in a wide variety of terrestrial vertebrates, including turtles [24], lizards [199], birds [31,78,140], mice [22,102], guinea pigs [208], cats [103,170,175], and humans [1]. The endbulb arises from the main axon as several gnarled branches that arborize repeatedly to enclose the postsynaptic cell in a nest of en passant swellings and terminal boutons (Fig.…”

Section: Innervationmentioning

confidence: 99%

Primary innervation of the avian and mammalian cochlear nucleus

Ryugo¹,

Parks²

2003

Brain Research Bulletin

115

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The auditory nerve of birds and mammals exhibits differences and similarities, but given the millions of years since the two classes diverged from a common ancestor, the similarities are much more impressive than the differences. The avian nerve is simpler than that of mammals, but share many fundamental features including principles of development, structure, and physiological properties. Moreover, the available evidence shows that the human auditory nerve follows this same general organizational plan. Equally impressive are reports that homologous genes in worms, flies, and mice exert the same heredity influences in man. The clear implication is that animal studies will produce knowledge that has a direct bearing on the human condition.

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“…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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Sequential alterations of neuronal architecture in nucleus magnocellularis of the developing chicken: A golgi study

Cited by 190 publications

References 29 publications

Pathway-specific variants of AMPA receptors and their contribution to neuronal signaling

Pathway-specific variants of AMPA receptors and their contribution to neuronal signaling

Primary innervation of the avian and mammalian cochlear nucleus

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

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