2014 Inner Ear Physiology

Outer hair cell function

Outer hair cells use their receptor potential to contract and exert force on the basilar membrane ---thereby generating a POSITIVE FEEDBACK MECHANISM which amplifies the vibration of the membrane in a nonlinear, highly frequency specific manner.  This force produces its own fluid wave, which is conducted back through the perilymph, vibrating the middle ear apparatus and generating sounds that are emitted from the ear (OTOACOUSTIC EMISSIONS).
Critical facts icon
OHC positive feedback cycle Therefore, there are five steps in the cochlear transduction process:
  1. Sound induces the travelling wave on the basilar membrane.
  2. Basilar membrane vibration causes stereocilia deflection.
  3. In both types of hair cells, the mechanical stimulus is transduced and receptor potentials are generated. In IHCs, this leads to neurotransmitter release and AP generation in underlying auditory nerve fibres.
  4. However, in OHCs, receptor potentials result in contraction, which amplifies the basilar membrane motion.
  5. This amplification increases the movement of the basilar membrane (positive feedback).
Email: Dr. Janet Fitzakerley | ©2014 University of Minnesota Medical School Duluth | Last modified: 15-feb-14 9:04 PM