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Maintenance of neuronal size gradient in MNTB requires sound-evoked activity.

Title: Maintenance of neuronal size gradient in MNTB requires sound-evoked activity.
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Name(s): Weatherstone, Jessica H, author
Kopp-Scheinpflug, Conny, author
Pilati, Nadia, author
Wang, Yuan, author
Forsythe, Ian D, author
Rubel, Edwin W, author
Tempel, Bruce L, author
Type of Resource: text
Genre: Journal Article
Text
Date Issued: 2017-02-01
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The medial nucleus of the trapezoid body (MNTB) is an important source of inhibition during the computation of sound location. It transmits fast and precisely timed action potentials at high frequencies; this requires an efficient calcium clearance mechanism, in which plasma membrane calcium ATPase 2 (PMCA2) is a key component. Deafwaddler (dfw(2J) ) mutant mice have a null mutation in PMCA2 causing deafness in homozygotes (dfw(2J) /dfw(2J) ) and high-frequency hearing loss in heterozygotes (+/dfw(2J) ). Despite the deafness phenotype, no significant differences in MNTB volume or cell number were observed in dfw(2J) homozygous mutants, suggesting that PMCA2 is not required for MNTB neuron survival. The MNTB tonotopic axis encodes high to low sound frequencies across the medial to lateral dimension. We discovered a cell size gradient along this axis: lateral neuronal somata are significantly larger than medially located somata. This size gradient is decreased in +/dfw(2J) and absent in dfw(2J) /dfw(2J) The lack of acoustically driven input suggests that sound-evoked activity is required for maintenance of the cell size gradient. This hypothesis was corroborated by selective elimination of auditory hair cell activity with either hair cell elimination in Pou4f3 DTR mice or inner ear tetrodotoxin (TTX) treatment. The change in soma size was reversible and recovered within 7 days of TTX treatment, suggesting that regulation of the gradient is dependent on synaptic activity and that these changes are plastic rather than permanent.NEW & NOTEWORTHY Neurons of the medial nucleus of the trapezoid body (MNTB) act as fast-spiking inhibitory interneurons within the auditory brain stem. The MNTB is topographically organized, with low sound frequencies encoded laterally and high frequencies medially. We discovered a cell size gradient along this axis: lateral neurons are larger than medial neurons. The absence of this gradient in deaf mice lacking plasma membrane calcium ATPase 2 suggests an activity-dependent, calcium-mediated mechanism that controls neuronal soma size.
Identifier: FSU_pmch_27881722 (IID), 10.1152/jn.00528.2016 (DOI), PMC5304411 (PMCID), 27881722 (RID), 27881722 (EID), jn.00528.2016 (PII)
Keywords: PMCA2, Auditory brain stem, Calyx of Held, Synaptic transmission, Tonotopic gradients
Grant Number: 568:LEI:IF, MR/K005170/1, U54 HD083091
Publication Note: This NIH-funded author manuscript originally appeared in PubMed Central at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5304411.
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_pmch_27881722
Owner Institution: FSU
Is Part Of: Journal of neurophysiology.
1522-1598
Issue: iss. 2, vol. 117

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Weatherstone, J. H., Kopp-Scheinpflug, C., Pilati, N., Wang, Y., Forsythe, I. D., Rubel, E. W., & Tempel, B. L. (2017). Maintenance of neuronal size gradient in MNTB requires sound-evoked activity. Journal Of Neurophysiology. Retrieved from http://purl.flvc.org/fsu/fd/FSU_pmch_27881722