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Physiology and anatomy of neurons in the medial superior olive of the mouse.

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journal contribution
posted on 25.01.2017, 16:40 by M. J. Fischl, R. M. Burger, M. Schmidt-Pauly, O. Alexandrova, J. L. Sinclair, B. Grothe, Ian D. Forsythe, C. Kopp-Scheinpflug
In mammals with good low-frequency hearing, the medial superior olive (MSO) computes sound location by comparing differences in the arrival time of a sound at each ear, called interaural time disparities (ITDs). Low-frequency sounds are not reflected by the head, and therefore level differences and spectral cues are minimal or absent, leaving ITDs as the only cue for sound localization. Although mammals with high-frequency hearing and small heads (e.g., bats, mice) barely experience ITDs, the MSO is still present in these animals. Yet, aside from studies in specialized bats, in which the MSO appears to serve functions other than ITD processing, it has not been studied in small mammals that do not hear low frequencies. Here we describe neurons in the mouse brain stem that share prominent anatomical, morphological, and physiological properties with the MSO in species known to use ITDs for sound localization. However, these neurons also deviate in some important aspects from the typical MSO, including a less refined arrangement of cell bodies, dendrites, and synaptic inputs. In vitro, the vast majority of neurons exhibited a single, onset action potential in response to suprathreshold depolarization. This spiking pattern is typical of MSO neurons in other species and is generated from a complement of Kv1, Kv3, and IH currents. In vivo, mouse MSO neurons show bilateral excitatory and inhibitory tuning as well as an improvement in temporal acuity of spiking during bilateral acoustic stimulation. The combination of classical MSO features like those observed in gerbils with more unique features similar to those observed in bats and opossums make the mouse MSO an interesting model for exploiting genetic tools to test hypotheses about the molecular mechanisms and evolution of ITD processing.

History

Citation

Journal of Neurophysiology, 2016, 116 (6), pp. 2676-2688

Author affiliation

/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/MBSP Non-Medical Departments/Neuroscience, Psychology and Behaviour

Version

VoR (Version of Record)

Published in

Journal of Neurophysiology

Publisher

American Physiological Society

issn

0022-3077

eissn

1522-1598

Acceptance date

19/09/2016

Copyright date

2016

Available date

25/01/2017

Publisher version

http://jn.physiology.org/content/116/6/2676

Language

en

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