Cochlear Mechanics Flashcards
In what direction does a rarefaction deflect the basilar membrane?
-Upward
In what direction does a rarefaction open the ion channels at the end of the stereocilia?
-Laterally
Tip links do what for stereocilia?
- Strengthen the structure
- Open/close ion channels in stereocilia
Why does the traveling wave goes from base to apex?
-Travels from a stiffness-limited region to mass-limited region
The tuning on the basilar membrane is improved by what?
-Active cochlear potentials, which add energy to the basal slope of the TW
How does the basilar membrane tuning of a zombie compare to an alive person?
-Broader
How does the sensitivity of a zombie compare to an alive person?
-Poorer
How long does the traveling wave take to go from base to apex in a human?
-10 ms
How does the tuning at the basilar membrane change with level?
-Broader tuning occurs at high intensity levels
What are on the axes of a tuning curve?
- X axis: BM amplitude (dB)
- Y axis: Stimulus frequency (Hz)
What frequencies show linear basilar membrane input-output functions?
-Off-frequencies away from the CF
Why were von Bekesy’s original Nobel prize winning measurements questioned?
- Subjects were dead, which is problematic if tuning is metabolic-dependent
- Stimuli needed to be presented at ~130 dB to get a response, which would not be feasible to replicate in live subjects due to cochlear damage
- Poor/broad tuning could not explain frequency selectivity in perception
How does the tuning curve of a hearing impaired person compared to a typical hearing person?
- Broader
- Poor frequency selectivity
Does the amplitude of the traveling wave grow or diminish as it travels down the cochlear duct? Why?
- Grows
- When the same amount of energy passes from a dense region to less dense reason, TW will increase in amplitude
After reaching the resonance point, how fast does the traveling wave dissipate? Why?
- Extremely quickly
- Reaches a mass-limited region whose nature makes wave motion impossible
