Hearing

Question 1

what 3 things are being detected by ears?

Answer 1

1. wavelength: pitch
2. amplitude: loudness
3. waveform - tone/timbre

Question 2

Function of ossicles?

Answer 2

matches air vibrations to fluid in inner ear

Question 3

tympanic membrane amplifies how much compared to inner ear??

Answer 3

200 fold

Question 4

3 chambers of cochlea?

Answer 4

1. scala vestiboli
2. scala media
3. scala tympani

Question 5

Basilar membrane is wider where? what does it detect?

Answer 5

wider at the base (detect high freq)

Question 6

apex of basilar membrane detects?

Answer 6

apex detect low freq

Question 7

how is basilar membrane organized?

Answer 7

tono-topically

Question 8

What is the organ of Corti?

Answer 8

what transduces sound waves to neural impulses

Question 9

auditory hair cell found between?

Answer 9

basilar membrane and tectoral membrane

Question 10

each hair cell have how many stereo cilia?

Answer 10

100

Question 11

how do you trigger auditory transduction?

Answer 11

basilar membrane vibrates> create shear forces on tectorial membrane> depolarize hair cells

Question 12

Hair cells use what ions to depolarize?

Answer 12

Potassium (K+)

Question 13

deflection of hair bundle toward kinocilum? away?

Answer 13

towards: depolarization (Ca2+ influx>glutamate)
away: hyperpolarization

Question 14

hair cell potassium channels are usually closed?

Answer 14

nope. partially open

Question 15

Are the hair cells depol and hyperpol amounts equal if the movement is equal?

Answer 15

Nope. larger depol

Question 16

Normal neurons has influx of what ion?

Answer 16

Na+

Question 17

what makes the potential difference in the cochlea re: ions?

Answer 17

Endolymph at +80mV (High K+)

Perilymph is at 0mV (Low K+)

Question 18

cell connections in inner ear are called?

Answer 18

vasa vascularis

Question 19

what’s the difference between inner and outer hair cells?

Answer 19

inner: 95% to brainstem nuclei
outer:
1. enhances tectorial membrane movement
2. efferent inputs from superior olivary complex

Question 20

how does outer hair cell affect inner hair cells?

Answer 20

low intensity stim>outer change length>increase basilar membrane movement>amplify to inner hair cells

Question 21

depol and hyperpol of outer hair cells causes what?

Answer 21

depol: contraction
hyperpol: elongation

Question 22

outer hair cells can be affected by what drugs?

Answer 22

aminoglycosides (gentamycin)
aspirin
ototoxicity

Question 23

without outer hair cells, how much less does the inner hair cells detect?

Answer 23

100 fold less

Question 24

Auditory pathway starting at hair cells:

Answer 24

Hair cells>CNVIII>spiral ganglion>cochlear nucleus>decussation>superior olive>lateral lemniscus>inferior colliculus (midbrain)>medial geniculate nucleus of thalamus>auditory cortex

Question 25

what does the anteroventral cochlear n. and superior olivary complex do?

Answer 25

mediate sound localization (horizontal plane)

Question 26

superior olivary complex consists of 3 things:

Answer 26

1. lateral superior olives
2. medial superior olives
3. trapezoid body

Question 27

2 ways to localize sound: know as what theory?

Answer 27

1. time difference
2. intensity difference
   Duplex theory

Question 28

Time difference for sound localization works well particularily with what?

Answer 28

low frequency sounds

Question 29

what detects the Time difference for sound localization?

Answer 29

medial superior olive

Question 30

intensity difference for sound localization for what kind of sound?

Answer 30

high frequency

Question 31

intensity difference for sound localization, how does the MNTB come into play?

Answer 31

MNTB: medial nucleus of trapezoid body inhibits contralateral LSO (lateral superior olive) excitation

Question 32

What is in brodmann’s area 41?

Answer 32

Herschls Gyrus (tonotopic)

Question 33

Higher order of auditory processing: which hemisphere for:

1. speech
2. music
3. environmental?

Answer 33

1. left
2. right
3. both

Question 34

3 causes of hearing loss within 3hr to 3 days include?

Answer 34

1. peripheral: guillan-barre, cancer
2. central: MS
3. cochlear:infection, trauma, ototoxicity, vascular