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Neuroscience & Mental Health Y2 > Sound Conduction and Transduction > Flashcards

Sound Conduction and Transduction Flashcards

1
Q

What % of UK population suffer from hearing loss

A

10%

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2
Q

Main causes of hearing loss? (5)

A 
Loud sounds
Genetics
Infections such meningitis
Drugs used for severe heart infections and chemo
Ageing
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3
Q

Hearing range of humans in Hz?

A

20Hz to 20kHz

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4
Q

1 Hertz = 1 X per second

A

Cycle

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5
Q

The ear can detect movements as small as …

A

a fraction of a nanometer, size of water molecule

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6
Q

We Watt range can we hear

A

1x10-12 to 1W

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7
Q

Outline sound detection:

A

Sound penetrates ear and causes tympanic membrane to vibrate
The vibration is transmitted to the cochlear which has hair cells along its length. when the hair cell deflects due to vibration we detect sound.

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8
Q

How many ossicles in an ear

A

3

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9
Q

Role of the ossicle?

A

To facilitate transmission of tympanic membrane vibration to the cochlear

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10
Q

What must the ossicle do to be able to carry out its role well

A

Match the impedance of the tympanic membrane and so reduce the loss in energy as the vibration goes from the air to the cochlea

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11
Q

The impedance measures ….

A

reluctance of a system in receiving energy from a source.

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12
Q

reluctance of a system in receiving energy from a source is called …

A

Impedance

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13
Q

resonant frequency is the …

A

The frequency at which the impedance of the system is minimal

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14
Q

The frequency at which the impedance of the system is minimal is called

A

resonant frequency

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15
Q

What controls the tension of the tympanic membrane (muscle and what the muscle controls)

A

Malleus and Incus position can be adjusted by the tensor tympanic muscle and stapedius muscles to control the tension of the tympanic membrane.

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16
Q

What muscles control tension of the tympanic membrane

A

Tympanic muscle and stapedius muscle

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17
Q

What is conductive hearing loss

A

when the ear is not capable of transmitting the vibration of sound waves onto the cochlea

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18
Q

What can cause conductive hearing loss in children

A

fluid accumulation in the middle ear is a common

cause of conductive hearing loss (cold)

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19
Q

What can cause conductive hearing loss in adults (3)

A

• Barotrauma is a temporary form of conductive hearing loss

An abnormal growth of bone (otosclerosis) can obstruct the ear
canal.

A perforated tympanic membrane is a form of conductive hearing
loss.

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20
Q

What is in the organ of Corti (4)

A

Basilar and tectorial membranes, the hair cells and and supporting cells

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21
Q

How does sound vibration cause movement in the Organ of Corti

A

The motion of the stapes generates a difference in pressure between the two liquid-filled chambers of the cochlea which in turns causes the vibration of the basilar membrane

On top of the basilar membrane are hair cells which on top of that has the tectorial membrane. the relative movement of the tectorial and basilar membrane due to the difference in pressures of the two chambers of the ear bends the air bundles adjacent to the hair cell which allows detection of sound

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22
Q

The basilar membrane is an X structure that vibrates at different Y in response to different frequencies

A

elastic

positions along its length

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23
Q

How does the impedance of the basilar membrane vary along its length, and what does this do to the local resonant frequency

A

Start is narrow and tough end is broad and floppy

this means the resonant frequency is different along its length

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24
Q

What are the microvilli of hair cells known as

A

Stereocilium

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25
Q

What is a hair cell characterised by

A

Bundles of 3 rows of stereo cilia

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26
Q

What is mechanotransduction of hair cells

A

The bending of stereocilia towards the tallest stereocilium (we can use a glass probe) changes the internal voltage of the cell, ultimately producing an electric signal that travels towards the brain. This is called Mechano-transduction (MT

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27
Q

Stereocilia are connected by XXXXX

A

filamentous linkages called tip links.

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28
Q

What ion is needed for stereo cilia to transmit noise

A

Ca

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29
Q

How does bending of stereo cilia produce an electrical current

A

Bending stretches the tip links connecting stereo cilia which in turn results in the opening of ion channels and a current generation and action potentials etc etc

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30
Q

Explain why the bending of stereo cilia producing an electrical current is not a passive process but an active one. What does the active work?

A

If we measure the stiffness of the tip links, before it pull the channels open tension increases, and after the channel opens the tension SHOULD decrease (think pulling door with a spring) however the tip link tension becomes negative, suggesting it actively does some work.

This is caused by the basilar membrane

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31
Q

Why is the active process of sound conduction in the hair cells necessary in sound conduction

A

A large portion of energy generated by sound is lost in the viscous damping effects of the cochlear liquids

32
Q

4 aspects of the active process of hair cells in sound conduction?

A

Amplification
Frequency tuning
Compressive nonlinearity
Spontaneous otoacoustic emission

33
Q

Explain amplification aspect of the active process of hair cells in sound conduction?

A

Basilar membrane amplifies the relevant frequency of the stimulus

34
Q

Explain the frequency tuning aspect of the active process of hair cells in sound conduction?

A

If you increase the amplitude of your stimulus, the basilar membrane will concentrate the sound at a particular frequency

35
Q

Explain the Compressive nonlinearity aspect of the active process of hair cells in sound conduction?

A

The hair cells basilar membrane amplifies low intensity sounds a lot more than high intensity sounds

36
Q

Explain Spontaneous otoacoustic emission aspect of the active process of hair cells in sound conduction?

A

if the active process is working well in a basilar membrane, a healthy human ear emit one or more pure tones when in a quiet environment

37
Q

2 types of hair cells? which is more common

A

Inner and outer

outer is more common

38
Q

Difference in 2 types of hair cells structure?

A

Outer hair cells have a V/U shaped bundles

Inner have a linear shaped hair bundle

39
Q

Where do most afferent projections of sound originate from

A

Inner hair cells

40
Q

Where do most efferent projections from the brain project to

A

Outer hair cells

41
Q

What is the role of outer hair cells?

A

help in Frequency selectivity and sensitivity enhancing

42
Q

What happens in electro mobility and what rate does it happen at

A

heir cell body shortens and elongates when their internal voltage is changed. This is called electromobility and can happen at a rate of 80 kHz

due to the reorientation of the protein prestin.

43
Q

Hair cells (mostly IHCs) form synapses with sensory neurons in the XX

A

cochlear ganglion (spiral ganglion).

44
Q

What is different about ganglion cells regarding their detection of frequencies

A

Each ganglion cell responds best to stimulations at a particular frequency.

45
Q

Where does tonotopic mapping begin

A

In the cochlear ganglion

46
Q

In the spiral/cochlear ganglion, Neurotransmitters are X at rest, but the rate changes in response to Y
(as a result of MT ion channel gating)

A

continuously released

a change of the presynaptic voltage

47
Q

What is tonotopic mapping

A

spatial arrangement of where sounds of different frequency are processed in the brain

48
Q

How do we encode middle and high frequency sounds considering the frequency is too high for a neuron to repeatedly fire and encode

A

We have multiple fibres which are phase locked that give a collective response at a frequency that single nerve fibres couldn’t manage individually

49
Q

sensorineural hearing loss is when the problem is in the …

A

sensory apparatus of the Inner ear or

in the vestibulocochlear nerve (retrocochlear hearing loss)

50
Q

the most widespread type of hearing loss is …

A

sensorineural hearing loss

51
Q

Causes of sensorineural hearing loss? (6)

A

Loud noises, headphones at high volume can cause temporary
or permanent hearing loss (Club: ~100 dB, Rock concert:
~120 dB)
• Ménière’s disease: excess of fluid in the cochlea
• Many genetics mutations affect the Organ of Corti
• Aminoglycoside antibiotics are toxic for hair cells
• Congenital diseases (rubella, toxoplasmosis)
• Ageing (presbycusis).

52
Q

Hearing loss is primarily due to …

A

the loss of hair cells

53
Q

How do cochlear implants work

A

bypass the dead cells and stimulate the nerve fibres directly: detect sounds, break them down into their constituent
frequencies and send the signal directly to the auditory nerve via antennas

54
Q

Path from Sound to the right auditory cortex? (8)

A

Sound Cochlea Auditory nerve fibre Ipsilateral cochlear nucleus Superior olivary nucleus Inferior colliculus Medial geniculate nucleus Right auditory cortex

55
Q

What is the tonotopic arrangement of neurons in the cochlear nucleus

A

(low frequencies

ventrally, high frequencies dorsally).

56
Q

What nucleus is responsible for locating the direction of high frequency sounds

A

dorsal cochlear nucleus

57
Q

What are spectral cues.

A

The ears detect and affect differently sounds coming from different directions due to their asymmetrical shape of the ear and the fact that high frequency sounds are wavelengths of the size of our head/ear/shoudlers

58
Q

What is the dorsal cochlear nucleus responsible for

A

locating the direction of high frequency sounds in the vertical plane

59
Q

what neurons are present in the cochlear nucleus (2)

A

T-STELLATE CELLS

BUSHY CELLS

60
Q

Which nucleus identifies direction of sounds in the vertical plane

A

dorsal cochlear nucleus

61
Q

Which nucleus identifies direction of sounds in the horizontal plane

A

Superior olivary complex

62
Q

Superior olivary complex does what

A

compares the bilateral activity of the cochlear nuclei

63
Q

MEDIAL SUPERIOR OLIVE does what

A

the interaural time difference is computed: sounds are first

detected at the nearest ear before they reach the other one.

64
Q

What cells are important in the medial superior olive

A

Bushy cells

65
Q

LATERAL SUPERIOR OLIVE does what

A

The LSO detects differences in intensity between the two ears (if a sound originates in the left it will be perceived louder in the left ear).

66
Q

A map of

interaural delay can be formed due to XX(birds).

A

DELAY LINES

67
Q

What happens at the INFERIOR COLLICULUS (2)

A

Here responses from different frequencies merge. In the IC all ascending
pathways converge and collateral sounds (e.g. talking bouncing off a wall) is filtered out

68
Q

What are the three parts of the inferior colliculus

A

entral nucleus, dorsal cortex and

external cortex

69
Q

Which part of the inferior colliculus is tonotopically arranged

A

central nucleus

70
Q

What is the precedence effect

A

Collateral sounds (e.g. talking bouncing off a wall) are filtered out

71
Q

What happens at the superior COLLICULUS (2)

A

Here auditory and visual maps merge.
The auditory map here created is fundamental for reflexes in orienting
the head and eyes to acoustic stimuli.

72
Q

The primary auditory cortex A1 is located in the ….

A

superior bank of the

temporal lobe

73
Q

Mapping of the auditory cortex?

A

Tonotopic

74
Q

What else is mapped in the auditory cortex apart from tone?

A

Loudness, rate, frequency modulation

75
Q

at what point in the auditory pathway is the earliest point tonotopic mapping starts

A

basilar membrane

Neuroscience & Mental Health Y2 (18 decks)

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