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Jonathan's Neuroscience > Hearing > Flashcards

Flashcards in Hearing Deck (31):
1

What does each wave component determine in sound
wavelength
amplitude
waveform

wavelength = frequency = pitch
amplitude = loudness
waveform = how smooth the sound

2

What is the function of the pinna

localise and collect sound

3

what is the function of ossicles?

impedance matching
without it, sound wave from air will just reflect off the fluid medium

4

how do we overcome the impedance?

by providing a 200x the pressure.

5

How is the 200x pressure generated?

by the relative size of tympanic membrane and the lever action of the ossicles

6

What are the three chambers of the cochlea?

Scala vestibuli
Scala media
Scala tympani

7

What's the difference between scala vestibuli and scala tympani?

Nothing really, they are continuous at the apex, but otherwise separated by the cochlear duct

They both carry perilymph

8

The apex is _______ and ______, which is able to detect ______ frequency sound.

The base is _______ and ______, which is able to detect ______ frequency sound

broad and floppy
low
narrow and frigid
high

9

T/F the tonotopic encoding of sound only occurs at the level of the cortex

False, tonotopic organisation begins at the basilar membrane

10

What does the organ of corti consist?

basilar membrane
inner and outer hair cells
tectorial membrane

11

What is found on top of the hair cells?

Stereocilia

12

What is the name of the tallest stereocilia

kinocilium

13

How is sound transduced into a neural signal?

sound wave causes movement of basilar membrane, which generates a shearing force along with tectorial membrane. The physical pulling on the hair cell channels leads to K+ dependent Ca+ influx, and neurotransmitter release

14

T/F K+ Channels are usually closed

False, they are partially open to create resting membrane potential

15

T/F the alternating pattern of depolarisation and hyperpolarisation is asymmetric

True, hyperpolarisation is much smaller. Hair cells tend to want to depolarise in the direction of kinocilium

16

What is the function of stria vascularis

it creates the K+ gradient between endolymph and perilymph

17

What is the function of inner hair cell?

they depolarise 95% of the afferent nerves going to the brainstem

18

What is the function of outer hair cell?

they provide efferent signals from superior olivary complex and amplify the movement of basilar membrane

19

Depolarisation causes OHC to ________
Hyperpolarisation causes OHC to _______

contract
elongate

20

what happens if we don't have functional OHC?

basilar membrane movement can be 100x less

21

T/F Aminoglycoside can affect the function of OHC

True, gentamicin is ototoxic, so we need to always monitor the amount of drug taken

22

the primary auditory neuron is a bipolar neuron. Which two locations does it project to?

dorsal cochlear nucleus, which then projects upward
ventral cochlear nucleus, which then projects to superior olive

23

What is the name of the auditory ascending tract? Which structure does it pass? which structure does this secondary neuron terminate at?

lateral lemniscus
inferior colliculus
medial geniculate nucleus

24

Which area in the brainstem is responsible for localisation of sound? What does this complex consist?

the superior olivary complex

lateral and medial superior olives
trapezoid body

25

What is the function of medial superior olive?

localisation of sound by time delay

26

What is the function of lateral superior olive?

localisation of sound by intensity difference

27

How do we localise sound by time delay

sound wave travels to the two ears at different time. The ear that's closer to the sound origin will fire AP before the other ear. Both sides fire AP towards a series of neurons in MSO. At one point, one neuron will receive both signals at the same time, and this neuron may have deviated from the centre, hence direction of sound can be determined

28

In localisation by intensity, one neuron will project to two areas of superior olive. What are the two areas?

ipsilateral LSO and contralateral medial nucleus of trapezoid body (MNTB)

29

How does intensity of sound help sound localisation?

the relative amount of excitation from LSO and inhibition from MNTB will determine where the sound is

There is more excitation on the neuron that's stimulated first

30

What is the auditory cortex also known as?

Herschls gyrus

31

T/F there is symmetrical representation of sound on both auditory cortices

False, different sounds can be lateralised
music is lateralised to the right
speech is isolated to the left