Hearing

Question 1

Wavelength refers to

Answer 1

pitch; short wavelength = high pitch (high frequency)

Question 2

Amplitude refers to

Answer 2

loudness; large amplitude = loud sound

Question 3

Waveform refers to

Answer 3

tone/timbre

Question 4

What is the function of the pinna?

Answer 4

Localization of sound and funnelling of waves into the middle ear

Question 5

Which ossicle is attached to the tympanic membrane?

Answer 5

Malleus

Question 6

Which ossicle is attached to the oval window?

Answer 6

Stapes

Question 7

What is the general role of the cochlea?

Answer 7

transforms physical motion of the oval window into a neural response

Question 8

What is the function of the middle ear?

Answer 8

match impedance of the air to the impedance of the fluid within the inner ear

Question 9

What are the 3 chambers of the cochlea?

Answer 9

Scala vestibuli
Scala media
Scala tympani

Question 10

What is the organisation of the basilar membrane with regards to frequency of sound?

Answer 10

stiffer at base (oval window) for high frequency sounds; wider and more floppy (like a flipper) at the apex for low frequency sounds

Question 11

What is the tonotopic organisation of hair cells of the basilar membrane?

Answer 11

towards the apex the hair cells will respond to low frequencies; as you move inwards toward the base each hair cell encodes increasing frequency of sound

Question 12

Where is the organ of corti?

Answer 12

Lies on the basilar membrane with the scala media above and the scala tympani below

Question 13

What is the function of the stereocilia?

Answer 13

project from the top of the hair cells to the tectorial membrane above; bending occurs as the basilar membrane moves, causes neuronal signaling

Question 14

What is the function of the tectorial membrane?

Answer 14

As the basilar membrane moves up and down in response to movement of the oval window, shear force movement of the tectorial membrane across the hair cells bends the stereocilia which signals to neurons

Question 15

Movement of inner hair cell stereocilia towards the kinocilium results in

Answer 15

full opening of K+ channels and tf K+ influx and depolarization of the cell; this opens VD-Ca channels (Ca in) leading to release of glutamate (NT)

Question 16

Movement of inner hair cell stereocilia away from the kinocilium results in

Answer 16

full closure of K+ channels and hyperpolarization of the cell, closing VDCCs and stopping glutamate release

Question 17

Displacement relative to the kinocilium favours

Answer 17

depolarization; ie depolarizations (moving towards) are much larger than hyperpolarizations (moving away)

Question 18

Depolarization and repolarization of hair cells is dependent on

Answer 18

K+

Question 19

The scala media contains

Answer 19

endolymph

Question 20

The scala tympani contains

Answer 20

perilymph

Question 21

The concentration of K+ in endolymph is

Answer 21

high (80mV)

Question 22

The concentration of K+ in perilymph is

Answer 22

low (0mV)

Question 23

What is the significance of high [K+] in the scala media?

Answer 23

Without it, K+ will not flow into hair cells and cause depolarization when K+ channels open

Question 24

What is unique about neuronal firing in hearing?

Answer 24

normally K+ is released in response to depolarization; in the inner ear depolarization depends on K+ influx due to the high [K+] around the hair cells

Question 25

Inner hair cells are

Answer 25

major transducers of sound waves to neural signals

Question 26

Outer hair cells

Answer 26

amplify movement of the basilar membrane through contraction in response to depolarization and elongation to hyperpolarization

Question 27

How do drugs impact on hearing?

Answer 27

inhibit movement of the outer hair cells which decreases movement and therefore amplification of the basilar membrane 100x

Question 28

The superior olivary complex is comprised of

Answer 28

medial and lateral superior olives and the trapezoid body

Question 29

How does the MSO localize sound?

Answer 29

measures the time that sound arrives at each ear, especially low frequencies

Question 30

Low frequency sounds are lateralized by the

Answer 30

MSO

Question 31

High frequency sounds are lateralized by the

Answer 31

LSO and inhibition of excitation of the contralateral LSO via the medial nuclei of the trapezoid body

Question 32

How does the LSO localize sound?

Answer 32

Sound inputs via the cochlear nuclei in the brainstem activate excitatory signals from LSO up to the brain, as well as an inhibitory signal via the MNTB to the contralateral LSO, inhibiting excitatory input from the opposite ear

Question 33

The auditory cortex is located

Answer 33

in Herschls gyrus on the superiolateral temporal lobes

Question 34

Speech sounds are heard in the

Answer 34

left hemisphere

Question 35

Environmental sounds are heard in

Answer 35

both hemispheres

Question 36

Music is heard in the

Answer 36

right hemisphere