Utricular Sensitivity during Hydrodynamic Displacements of the Macula

AbstractTo explore the effects of cochlear hair cell displacement, researchers have previously monitored functional and mechanical responses during low-frequency (LF) acoustic stimulation of the cochlea. The induced changes are believed to result from modulation of the conductance of mechano-electrical transduction (MET) channels on cochlear hair cells, along with receptor potential modulation. It is less clear how, or if, vestibular hair cell displacement affects vestibular function. Here, we have used LF (<20  Hz) hydrodynamic modulation of the utricular macula position, whilst recording functional and mechanical responses, to investigate the effects of utricular macula displacement. Measured responses included the Utricular Microphonic (UM), the vestibular short-latency evoked potential (VsEP), and las er Doppler vibrometry recordings of macular position. Over 1 cycle of the LF bias, the UM amplitude and waveform were cyclically modulated, with Boltzmann analysis suggesting a cyclic modulation of the vestibular MET gating. The VsEP amplitude was cyclically modulated throughout the LF bias, demons trating a relative increase (~20–50 %; re baseline) and decrease (~10–20 %; re baseline), which is believed to be related to the MET conductance and vestibular hair cell sensitivity. The relationship between macular displacement and changes in UM and VsEP responses was consistent within and ac ross animals. These results suggest that the sensory structures underlying th...

Source: JARO - Journal of the Association for Research in Otolaryngology - August 10, 2020 Category: ENT & OMF Source Type: research