inner ear

Question 1

Be able to label the parts of the organ of corti

Answer 1

Look on google doc notes

Question 2

What are the characteristics of IHC

Answer 2

stereocilia in U pattern

1 row

Question 3

What are the characteristics of OHC

Answer 3

stereocilia in V or W pattern

3 rows

*they can emit their own sound because they have a feature called motility

Question 4

What is motility

Answer 4

existing or capable of movement (the ability to move spontaneously and actively)

Question 5

What is the primary role of the mechanical response of the inner ear

Answer 5

convert mechanical vibrations at the stapes and of the inner ear fluids into neural (electrical) responses in the auditory nerve

Question 6

How is the motion of the basilar membrane described

Answer 6

as a paradoxical traveling wave

Question 7

Why is the basilar membrane paradoxical

Answer 7

if you stimulate the apical end, the basal end will move first

Basilar membrane is organized so that it is represented by independent oscillators

Even if you damage one place it can still function
Stiffness gradient works across the entire length of the basilar membrane to enable tonotopic organization

Question 8

What is the evidence that the basilar membrane is not stretched

Answer 8

paradoxical traveling waves

if you cut the BM it does not stretch

Question 9

What are the two types of otoacoustic emissions

Answer 9

spontaneous

evoke

Question 10

What are otoacoustic emissions evidence of

Answer 10

evidence that the basilar membrane is nonlinear

Question 11

In what percent of ears do spontaneous emissions occur

Answer 11

50%

Question 12

What are transient evoked otoacoustic emissions

Answer 12

present a short duration sound in the ear canal of a person

sound sets the outer hair cells into oscillation

can record the echo in the ear canal

Question 13

What are distortion produce otoacoustic emissions

Answer 13

present subject with 2 primary tones: f1 and f2

f2/f1 = the biggest cubic distortion product

measure energy at 2f1-f2 to record the emission

if its audible its a combination tone

f2-f1 = simple difference tone

Question 14

What are cochlear voltages

Answer 14

a voltage in the inner ear

Question 15

What is an alternating current

Answer 15

can either be cochlear microphonic (mimics the stimulus) or action potential

in both cases the stimulus is induced

Question 16

What is direct current

Answer 16

can either be resting potentials or summating potentials

summating potentials have stimulus induced and are helpful in diagnosing meneire’s disease

Question 17

What is resting potential and what are the two types

Answer 17

voltages that are present in the cochlea in the absence of sound

endocochlear potential: an extracellular potential that you can record in the endolymph

hair cell potential: an intracellular potential

Question 18

What is the total voltage gradient between the EP and the hair cell potential

Answer 18

160 mV

Question 19

anything that we hear has to be represented through what?

Answer 19

the firing of the 8th auditory nerve

Question 20

What are afferent fibers
(what are the two types)

Answer 20

carry information up to the central auditory system

radial fibers: comprise 85-95% of the total number
- innervate only inner hair cells
- 20:1 ICH ratio, many to 1
- primarily responsible for carrying information about sound to the brain

outer spiral fibers: comprise 5-15% of fibers
- innervate only the outer hair cells
- unmyelinated, skinny, slowly conducting
- 1:10 OHC ratio, 1 to many)
unknown function

Question 21

what are efferent fibers

Answer 21

carry information back down from the central auditory system

Question 22

What’s on the vertical and horizontal axes of a neural rate intensity function

Answer 22

x axis = intensity (dB SPL)

y axis = firing rate (spikes/sec)

Question 23

when no sound is presented, what will the neuron fire at

Answer 23

its spontaneous rate

Question 24

What kind of relationship do Spontaneous rate and threshold have

Answer 24

inverse