In Vivo Optogenetics Reveals Control of Cochlear Electromechanical Responses by Supporting Cells

Area of Science:

• Auditory Neuroscience
• Cellular Biophysics
• Sensory Physiology

Background:

• Cochlear sensitivity relies on outer hair cells (OHCs) within the organ of Corti (OoC), supported by surrounding cells.
• The precise role of supporting cells (Deiters' cells [DCs] and outer pillar cells [OPCs]) in cochlear function has remained unclear in vivo.

Purpose of the Study:

• To investigate the in vivo function of OoC supporting cells in cochlear sensitivity control.
• To establish the interdependency between OHCs and supporting cells in the cochlea.

Main Methods:

• Conditional expression of channelrhodopsin-2 (ChR2) in mouse DCs and OPCs.
• In vivo optogenetic stimulation of supporting cells within the OoC.
• Measurement of cochlear mechanical and electrical responses, including basilar membrane displacement and OHC voltage.

Main Results:

• Optogenetic activation of supporting cells reversibly suppressed their normal function and cochlear sensitivity.
• Suppression of supporting cells altered OHC mechanoelectrical transduction operating points and affected responses to sound.
• Interference with supporting cell function accelerated recovery from temporary noise-induced hearing loss.

Conclusions:

• Deiters' cells and outer pillar cells are crucial for controlling cochlear responses and normal hearing.
• Supporting cells play a role in the recovery from acoustic desensitization.
• This study provides the first direct in vivo evidence for the functional integration of supporting cells and OHCs in cochlear fine-tuning.