Topographic organization in the auditory brainstem of juvenile mice is disrupted in congenital deafness

Richardson N. Leao, Hong Sun, Katarina Svahn, Amy Berntson, Monique Youssoufian, Antonio G. Paolini, Robert E.W. Fyffe, Bruce Walmsley*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    83 Citations (Scopus)

    Abstract

    There is an orderly topographic arrangement of neurones within auditory brainstem nuclei based on sound frequency. Previous immunolabelling studies in the medial nucleus of the trapezoid body (MNTB) have suggested that there may be gradients of voltage-gated currents underlying this tonotopic arrangement. Here, our electrophysiological and immunolabelling results demonstrate that underlying the tonotopic organization of the MNTB is a combination of medio-lateral gradients of low-and high-threshold potassium currents and hyperpolarization-activated cation currents. Our results also show that the intrinsic membrane properties of MNTB neurones produce a topographic gradient of time delays, which may be relevant to sound localization, following previous demonstrations of the importance of the timing of inhibitory input from the MNTB to the medial superior olive (MSO). Most importantly, we demonstrate that, in the MNTB of congenitally deaf mice, which exhibit no spontaneous auditory nerve activity, the normal tonotopic gradients of neuronal properties are absent. Our results suggest an underlying mechanism for the observed topographic gradient of neuronal firing properties in the MNTB, show that an intrinsic neuronal mechanism is responsible for generating a topographic gradient of time-delays, and provide direct evidence that these gradients rely on spontaneous auditory nerve activity during development.

    Original languageEnglish
    Pages (from-to)563-578
    Number of pages16
    JournalJournal of Physiology
    Volume571
    Issue number3
    DOIs
    Publication statusPublished - Mar 2006

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