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Edwin W Rubel - One of the best experts on this subject based on the ideXlab platform.

  • effect of altered neuronal activity on cell size in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of the gerbil
    The Journal of Comparative Neurology, 1994
    Co-Authors: Thomas R Pasic, David Moore, Edwin W Rubel
    Abstract:

    Activity-dependent transneuronal regulation of neuronal soma size has been studied in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of adolescent gerbils. Cochlear ablation or tetrodotoxin has been used to eliminate afferent electrical activity in auditory nerve fibers permanently or for 24 or 48 hours. Previous studies have shown that the cross-sectional area of spherical cell somata in the ipsilateral anteroventral cochlear nucleus decreases within 24 hours of electrical activity blockade with tetrodotoxin, which is fully reversible when activity is restored. The present findings extend this work by directly comparing the results of unilateral blockade of auditory nerve action potentials or unilateral cochlear ablation on the size of spherical and globular cell bodies in the ventral cochlear nucleus with changes produced by the same manipulations in third-order cells, principal neurons in the medial nucleus of the Trapezoid body. Soma size in both ventral cochlear nucleus cell types decreases reliably by 24 hours after cochlear removal or eighth nerve activity blockade by tetrodotoxin. Soma size of neurons in the contralateral medial nucleus of the Trapezoid body decreases 48 hours, but not 24 hours, after either manipulation. When activity in auditory nerve fibers is allowed to resume for 7 days following a 48-hour activity blockade, soma size fully recovers in the medial nucleus of the Trapezoid body as well as in ventral cochlear nucleus neurons. We also report that the cross-sectional area of neuronal soma in the medial nucleus of the Trapezoid body is larger in lateral regions of medial nucleus of the Trapezoid body (low-frequency representation) than in the medial regions of the nucleus (high-frequency representation). We conclude that cell body size changes in brainstem auditory neurons are reversible and that the signals associated with the loss and subsequent recovery of soma size are activity related. However, the delayed effect of activity deprivation in the medial nucleus of the Trapezoid body suggests that trophic substances released by afferent axons may contribute to the maintenance of anatomical characteristics. © 1994 Wiley-Liss, Inc.

  • effect of altered neuronal activity on cell size in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of the gerbil
    The Journal of Comparative Neurology, 1994
    Co-Authors: Thomas R Pasic, David R Moore, Edwin W Rubel
    Abstract:

    Activity-dependent transneuronal regulation of neuronal soma size has been studied in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of adolescent gerbils. Cochlear ablation or tetrodotoxin has been used to eliminate afferent electrical activity in auditory nerve fibers permanently or for 24 or 48 hours. Previous studies have shown that the cross-sectional area of spherical cell somata in the ipsilateral anteroventral cochlear nucleus decreases within 24 hours of electrical activity blockade with tetrodotoxin, which is fully reversible when activity is restored. The present findings extend this work by directly comparing the results of unilateral blockade of auditory nerve action potentials or unilateral cochlear ablation on the size of spherical and globular cell bodies in the ventral cochlear nucleus with changes produced by the same manipulations in third-order cells, principal neurons in the medial nucleus of the Trapezoid body. Soma size in both ventral cochlear nucleus cell types decreases reliably by 24 hours after cochlear removal or eighth nerve activity blockade by tetrodotoxin. Soma size of neurons in the contralateral medial nucleus of the Trapezoid body decreases 48 hours, but not 24 hours, after either manipulation. When activity in auditory nerve fibers is allowed to resume for 7 days following a 48-hour activity blockade, soma size fully recovers in the medial nucleus of the Trapezoid body as well as in ventral cochlear nucleus neurons. We also report that the cross-sectional area of neuronal soma in the medial nucleus of the Trapezoid body is larger in lateral regions of medial nucleus of the Trapezoid body (low-frequency representation) than in the medial regions of the nucleus (high-frequency representation). We conclude that cell body size changes in brainstem auditory neurons are reversible and that the signals associated with the loss and subsequent recovery of soma size are activity related. However, the delayed effect of activity deprivation in the medial nucleus of the Trapezoid body suggests that trophic substances released by afferent axons may contribute to the maintenance of anatomical characteristics.

Justin M. Zook - One of the best experts on this subject based on the ideXlab platform.

  • projections to the medial superior olive from the medial and lateral nuclei of the Trapezoid body in rodents and bats
    The Journal of Comparative Neurology, 1992
    Co-Authors: N. Kuwabara, Justin M. Zook
    Abstract:

    In this study we present direct evidence of axonal projections from both the medial and lateral nuclei of the Trapezoid body to the medial superior olive. Projections were traced by intracellularly labeling cells and axons in a tissue slice preparation of two rodent species, Mus musculus and Meriones unguiculatus and two bat species, Eptesicus fuscus and Pteronotus parnellii. The main axon of most principal cells in the medial nucleus of the Trapezoid body gives off one or more collateral branches which arborize within the medial superior olive. These collateral axons form small bouton-like swellings which primarily contact somata within the central cell column in the medial superior olive. Likewise, labeled elongate and multipolar cells of the lateral nucleus of the Trapezoid body send axons to both the medial and lateral superior olives. These axons also form perisomatic contacts in both target nuclei. These two sets of projections may relay ascending input to the medial superior olive and the lateral superior olive; the medial nucleus of the Trapezoid body is known to relay input from the contralateral ventral cochlear nucleus, and the lateral nucleus of the Trapezoid body may relay input from the ipsilateral ventral cochlear nucleus. These projections offer two routes for indirect, possibly inhibitory input to reach the medial superior olive from both cochlear nuclei. These indirect, inhibitory pathways may parallel the direct excitatory projections the medial superior olive receives from each cochlear nucleus.

  • afferents to the medial nucleus of the Trapezoid body and their collateral projections
    The Journal of Comparative Neurology, 1991
    Co-Authors: N. Kuwabara, Ralph A. Dicaprio, Justin M. Zook
    Abstract:

    Cells and axons that supply direct afferent input to the medial nucleus of the Trapezoid body are described. Afferents were intracellularly labeled in brainstem tissue slices of two rodent and two bat species. The main afferents are calyciferous axons from globular bushy cells of the ventral cochlear nucleus. Calyciferous axons were highly consistent across species, projecting directly from the cochlear nucleus, across the midline in the Trapezoid body, to the contralateral medial nucleus of the Trapezoid body. Within the target nucleus, a typical axon turned sharply away from horizontal to form a large ending, the calyx of Held, around the soma of a single principal cell. Three groups of calyciferous axons were classified based on the path taken from bend to calyx. In subjects younger than four weeks, single axons often formed two calyces, each on a different cell. These calyx pairs were often found on adjacent or vertically aligned cells. In older animals, calyx pairs were more closely aligned, but fewer double calyx axons were seen. A secondary focus of this study was the system of thin collateral branches that characterizes calyciferous axons in all species. The projection patterns of these collaterals suggest that calyciferous axons may provide ascending input to periolivary cell groups with descending projections. In addition to calyciferous afferents, labeled cells that provide input to the medial nucleus of the Trapezoid body from adjacent periolivary cell groups are described. Also described is a type of afferent that descends from the level of the lateral lemniscus to the medial nucleus of the Trapezoid body.

Thomas R Pasic - One of the best experts on this subject based on the ideXlab platform.

  • effect of altered neuronal activity on cell size in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of the gerbil
    The Journal of Comparative Neurology, 1994
    Co-Authors: Thomas R Pasic, David Moore, Edwin W Rubel
    Abstract:

    Activity-dependent transneuronal regulation of neuronal soma size has been studied in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of adolescent gerbils. Cochlear ablation or tetrodotoxin has been used to eliminate afferent electrical activity in auditory nerve fibers permanently or for 24 or 48 hours. Previous studies have shown that the cross-sectional area of spherical cell somata in the ipsilateral anteroventral cochlear nucleus decreases within 24 hours of electrical activity blockade with tetrodotoxin, which is fully reversible when activity is restored. The present findings extend this work by directly comparing the results of unilateral blockade of auditory nerve action potentials or unilateral cochlear ablation on the size of spherical and globular cell bodies in the ventral cochlear nucleus with changes produced by the same manipulations in third-order cells, principal neurons in the medial nucleus of the Trapezoid body. Soma size in both ventral cochlear nucleus cell types decreases reliably by 24 hours after cochlear removal or eighth nerve activity blockade by tetrodotoxin. Soma size of neurons in the contralateral medial nucleus of the Trapezoid body decreases 48 hours, but not 24 hours, after either manipulation. When activity in auditory nerve fibers is allowed to resume for 7 days following a 48-hour activity blockade, soma size fully recovers in the medial nucleus of the Trapezoid body as well as in ventral cochlear nucleus neurons. We also report that the cross-sectional area of neuronal soma in the medial nucleus of the Trapezoid body is larger in lateral regions of medial nucleus of the Trapezoid body (low-frequency representation) than in the medial regions of the nucleus (high-frequency representation). We conclude that cell body size changes in brainstem auditory neurons are reversible and that the signals associated with the loss and subsequent recovery of soma size are activity related. However, the delayed effect of activity deprivation in the medial nucleus of the Trapezoid body suggests that trophic substances released by afferent axons may contribute to the maintenance of anatomical characteristics. © 1994 Wiley-Liss, Inc.

  • effect of altered neuronal activity on cell size in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of the gerbil
    The Journal of Comparative Neurology, 1994
    Co-Authors: Thomas R Pasic, David R Moore, Edwin W Rubel
    Abstract:

    Activity-dependent transneuronal regulation of neuronal soma size has been studied in the medial nucleus of the Trapezoid body and ventral cochlear nucleus of adolescent gerbils. Cochlear ablation or tetrodotoxin has been used to eliminate afferent electrical activity in auditory nerve fibers permanently or for 24 or 48 hours. Previous studies have shown that the cross-sectional area of spherical cell somata in the ipsilateral anteroventral cochlear nucleus decreases within 24 hours of electrical activity blockade with tetrodotoxin, which is fully reversible when activity is restored. The present findings extend this work by directly comparing the results of unilateral blockade of auditory nerve action potentials or unilateral cochlear ablation on the size of spherical and globular cell bodies in the ventral cochlear nucleus with changes produced by the same manipulations in third-order cells, principal neurons in the medial nucleus of the Trapezoid body. Soma size in both ventral cochlear nucleus cell types decreases reliably by 24 hours after cochlear removal or eighth nerve activity blockade by tetrodotoxin. Soma size of neurons in the contralateral medial nucleus of the Trapezoid body decreases 48 hours, but not 24 hours, after either manipulation. When activity in auditory nerve fibers is allowed to resume for 7 days following a 48-hour activity blockade, soma size fully recovers in the medial nucleus of the Trapezoid body as well as in ventral cochlear nucleus neurons. We also report that the cross-sectional area of neuronal soma in the medial nucleus of the Trapezoid body is larger in lateral regions of medial nucleus of the Trapezoid body (low-frequency representation) than in the medial regions of the nucleus (high-frequency representation). We conclude that cell body size changes in brainstem auditory neurons are reversible and that the signals associated with the loss and subsequent recovery of soma size are activity related. However, the delayed effect of activity deprivation in the medial nucleus of the Trapezoid body suggests that trophic substances released by afferent axons may contribute to the maintenance of anatomical characteristics.

David C Ross - One of the best experts on this subject based on the ideXlab platform.

  • quantitative distribution of choline acetyltransferase activity in rat Trapezoid body
    Hearing Research, 2018
    Co-Authors: Lauren A Linker, Lissette Carlson, Donald A. Godfrey, Judy A Parli, David C Ross
    Abstract:

    Abstract There is evidence for a function of acetylcholine in the cochlear nucleus, primarily in a feedback, modulatory effect on auditory processing. Using a microdissection and quantitative microassay approach, choline acetyltransferase activity was mapped in the Trapezoid bodies of rats, in which the activity is relatively higher than in cats or hamsters. Maps of series of sections through the Trapezoid body demonstrated generally higher choline acetyltransferase activity rostrally than caudally, particularly in its portion ventral to the medial part of the spinal trigeminal tract. In the lateral part of the Trapezoid body, near the cochlear nucleus, activities tended to be higher in more superficial portions than in deeper portions. Calculation of choline acetyltransferase activity in the total Trapezoid body cross-section of a rat with a comprehensive Trapezoid body map gave a value 3–4 times that estimated for the centrifugal labyrinthine bundle, which is mostly composed of the olivocochlear bundle, in the same rat. Comparisons with other rats suggest that the ratio may not usually be this high, but it is still consistent with our previous results suggesting that the centrifugal cholinergic innervation of the rat cochlear nucleus reaching it via a Trapezoid body route is much higher than that reaching it via branches from the olivocochlear bundle. The higher choline acetyltransferase activity rostrally than caudally in the Trapezoid body is consistent with evidence that the centrifugal cholinergic innervation of the cochlear nucleus derives predominantly from locations at or rostral to its anterior part, in the superior olivary complex and pontomesencephalic tegmentum.

N. Kuwabara - One of the best experts on this subject based on the ideXlab platform.

  • projections to the medial superior olive from the medial and lateral nuclei of the Trapezoid body in rodents and bats
    The Journal of Comparative Neurology, 1992
    Co-Authors: N. Kuwabara, Justin M. Zook
    Abstract:

    In this study we present direct evidence of axonal projections from both the medial and lateral nuclei of the Trapezoid body to the medial superior olive. Projections were traced by intracellularly labeling cells and axons in a tissue slice preparation of two rodent species, Mus musculus and Meriones unguiculatus and two bat species, Eptesicus fuscus and Pteronotus parnellii. The main axon of most principal cells in the medial nucleus of the Trapezoid body gives off one or more collateral branches which arborize within the medial superior olive. These collateral axons form small bouton-like swellings which primarily contact somata within the central cell column in the medial superior olive. Likewise, labeled elongate and multipolar cells of the lateral nucleus of the Trapezoid body send axons to both the medial and lateral superior olives. These axons also form perisomatic contacts in both target nuclei. These two sets of projections may relay ascending input to the medial superior olive and the lateral superior olive; the medial nucleus of the Trapezoid body is known to relay input from the contralateral ventral cochlear nucleus, and the lateral nucleus of the Trapezoid body may relay input from the ipsilateral ventral cochlear nucleus. These projections offer two routes for indirect, possibly inhibitory input to reach the medial superior olive from both cochlear nuclei. These indirect, inhibitory pathways may parallel the direct excitatory projections the medial superior olive receives from each cochlear nucleus.

  • afferents to the medial nucleus of the Trapezoid body and their collateral projections
    The Journal of Comparative Neurology, 1991
    Co-Authors: N. Kuwabara, Ralph A. Dicaprio, Justin M. Zook
    Abstract:

    Cells and axons that supply direct afferent input to the medial nucleus of the Trapezoid body are described. Afferents were intracellularly labeled in brainstem tissue slices of two rodent and two bat species. The main afferents are calyciferous axons from globular bushy cells of the ventral cochlear nucleus. Calyciferous axons were highly consistent across species, projecting directly from the cochlear nucleus, across the midline in the Trapezoid body, to the contralateral medial nucleus of the Trapezoid body. Within the target nucleus, a typical axon turned sharply away from horizontal to form a large ending, the calyx of Held, around the soma of a single principal cell. Three groups of calyciferous axons were classified based on the path taken from bend to calyx. In subjects younger than four weeks, single axons often formed two calyces, each on a different cell. These calyx pairs were often found on adjacent or vertically aligned cells. In older animals, calyx pairs were more closely aligned, but fewer double calyx axons were seen. A secondary focus of this study was the system of thin collateral branches that characterizes calyciferous axons in all species. The projection patterns of these collaterals suggest that calyciferous axons may provide ascending input to periolivary cell groups with descending projections. In addition to calyciferous afferents, labeled cells that provide input to the medial nucleus of the Trapezoid body from adjacent periolivary cell groups are described. Also described is a type of afferent that descends from the level of the lateral lemniscus to the medial nucleus of the Trapezoid body.