Basilar membrane vibration in the gerbil hemicochlea

Claus Peter Richter*, Burt N. Evans, Roxanne Edge, Peter Dallos

*Corresponding author for this work

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

Excised gerbil cochleae were cut along the mid-modiolar plane (hemicochlea). Along one-half turn of this preparation, fluorescent microbeads were placed on the basilar membrane (BM). The BM was vibrated with click stimuli (50 μs) produced mechanically by a piezo pusher. The stimulus delivery probe could be positioned either more apical or more basal from the beads. Vibration patterns were measured with a wide bandwidth photomultiplier from the movements of the beads. When the probe was positioned more basal, the responses to click stimuli were brief, damped sinusoids. According to the fast Fourier transforms (FFTs) of the averaged time wave forms, the best frequency between successive beads decreased toward the apex (0.8 octave/mm). Sharpness of tuning of the normalized FFT spectra (NQ(10dB)) on average was 1.5. Response amplitude at a fixed input level, measured at different beads away from the stimulation site, dropped exponentially (58 dB/mm). In addition, for each individual bead, amplitude dropped linearly with decreasing stimulus intensity. In experiments where the stimulating probe was placed more apical, two major properties were observed: first, beads revealed only the spectral components present in the motion of the probe. Second, magnitude reduction of the displacement of the cochlear partition was greater, on average 155 dB/mm, indicating a lack of significant propagation in the reverse direction.

Original languageEnglish (US)
Pages (from-to)2255-2264
Number of pages10
JournalJournal of neurophysiology
Volume79
Issue number5
DOIs
StatePublished - May 1998

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology

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