380 Exam #1

Front 1

The inner ear includes the following structures

Back 1

vestibule
scala tympani
basilar membrane

Front 2

Which of the following structures inside cochlea houses the hair cells?

Back 2

*scala media

Front 3

The basilar membrane is

Back 3

*narrow and stiff at the base (high frequencies)and wide and flexible at the apex (low frequencies)

Front 4

The cochlear coils about

Back 4

2 1/2

Front 5

The hair cells are sandwiched by

Back 5

the basilar membrane and tectorial membrane

Front 6

Select the best answer from the following statements about BM responses to tones

Back 6

The basal end has max response to high frequency tones and the apical end to low frequency tones

Front 7

The vast majority of the auditory nerve fibers have synaps on

Back 7

inner hair cells

Front 8

Which of the following structures will respond to a tone at its frequency?

Back 8

Basilar membrane
inner hair cells
stapes and outer hair cells

Front 9

Which of the following is responsible for the frequency analysis by the basilar membrane?

Back 9

Different parts of the basilar membrane have different resonant frequencies

Front 10

Which of the following structure is likely the source of the endocochlear potential?

Back 10

stria vascularis

Front 11

The relative motion between the tectorial membrane and the basilar membrane leads to

Back 11

the bending of the OHC cilia and the OHC depolarization
the bending of the IHC cilia and the IHC depolarization
the OHC motility and the release of neurotransmitter in the IHC

Front 12

Which of the following potentials appear in the absence of acoustic stimulation?

Back 12

resting potential

Front 13

The potential difference across the top of the hair cells between the inside and outside of the hair cells is

Back 13

150mV

Front 14

.While the ___ serve to enhance sensitivity and frequency selectivity the ___ serve a role in sensory transduction for hearing

Back 14

OHCs; IHCs

Front 15

Clicks are used to measure

Back 15

TEOAEs

Front 16

About 90% of afferent fibers are ____ fibers and they innervate _____

Back 16

Type 1; IHCs

Front 17

In human cochlea, each auditory nerve innervates mostly ______ IHC(s) and each IHC receive ____ auditory nerve(s)

Back 17

one; eight

Front 18

Within the nerve bundle leaving the cochlea

Back 18

the ANs innervating low frequency are in the middle

Front 19

A Rate-Level function of an AN includes the following information

Back 19

Spontaneous discharge rate
Saturation discharge rate
Dynamic rage of a single nerve

Front 20

Choose the correct statement from the following:

Back 20

ANs with high spontaneous rate tend to have low threshold

Front 21

Tuning curve of a single nerve reflects

Back 21

How sharply the nerve is tuned to its best frequency
The stimulus level needed to excite a fixed discharge rate at different frequencies
the frequency selectivity of the BM responses to sounds

Front 22

The neural representation of stimulus spectrum is called

Back 22

an excitation pattern

Front 23

The entire range of audible sound intensity is likely encoded in the auditory system by

Back 23

the discharge rate of ANs with different spontaneous rates and different best frequencies

Front 24

The sound frequency is encoded in auditory nerve by

Back 24

a place code
a temporal code

Front 25

What are the four pieces of information that one can obtain from a rate level function?

Back 25

Spontaneous rate, threshold, dynamic range and saturation)

Front 26

How does the neural-response threshold depend on the spontaneous response rate?

Back 26

High SR – Low TH)

Front 27

List three pieces of information that a tuning curve shows?

Back 27

Best Freq; sensitivity; sharpness

Front 28

What is the ‘dynamic-range problem’ in hearing?

Back 28

Single nerve only covers 30 dB but all of hearing is 120 dB)

Front 29

How does the auditory system overcome the dynamic-range problem, list two mechanisms?

Back 29

1. Combine fibers at same best frequencies with different thresholds

2. Combine fiber at different best frequencies with same thresholds

Front 30

What is the basis for the place coding of stimulus frequency?

Back 30

Place theory- frequency mapped to place on basilar membrance

Front 31

What is the basis for the temporal coding of stimulus frequency?

Back 31

Temporal theory- frequency represented by temporal pattern of discharges

Front 32

Which histograms of auditory nerve discharge shows the neural activity can follow the temporal variation of the stimulus amplitude?

Back 32

(PST, period, and interval

Front 33

List four pieces of information or characteristics that can be observed in a PST histogram in response to a steady tone.

Back 33

Spontaneous activity, Onset response, adaptation and recovery

Front 34

In a two-tone suppression, describe what happens to the neural response to a primary tone is affected when a second tone at an adjacent frequency is introduced.

Back 34

reduction of discharge rate

Front 35

What combinations of level and frequency for the second tone are necessary for two-tone suppression to occur?

Back 35

Hint: remember the tuning curve with a shaded area on each side} (Look for the shaded region and if the tone is in that level of frequency and level of dB it will mask it)

Front 36

What is the significance in auditory function of two-tone suppression?

Back 36

masking

Front 37

(Very Important) Describe the sequence of events that takes place in the inner ear during sound stimulation from the stapes to the auditory nerve.

Back 37

(Stapes vibrates, fluid vibrates, Basilar Membrane vibrates, bends outside hair cells and OHC depolarizes and contracts and expands, pumps energy back to BM energy picked up by Inner Hair Cells, depolarizes inner hair cells leads to release of neurotransmitter)

Front 38

What is the fluid and the potential inside the scala media?

Back 38

Endolymph; +80 mV

Front 39

Of which ion does the fluid (endolymph) have a high concentration

Back 39

potassium K+

Front 40

What is the fluid and potential inside the other two scalas: vestibular and tympani?

Back 40

(Perilymph)

Front 41

Of which ion does the fluid (perilymph) have a high concentration?

Back 41

sodium Na+

Front 42

What is the resting potential inside the hair cells?

Back 42

-70mV

Front 43

Describe how the physical properties (width and stiffness) and the resonant frequency change along the basilar membrane

Back 43

(Stiff and narrow near base, tuned to high frequencies)

Front 44

What the typical length of a human cochlear

Back 44

35mm

Front 45

Which OAE is evoked by clicks

Back 45

TEOAE

Front 46

Which OAE is evoked by a pair of tones?

Back 46

DPOAE

Front 47

The vast majority of the auditory afferent nerves are of this type of nerve fibers

Back 47

type 1

Front 48

On which hair cells do these fibers have synapses

Back 48

IHCs

Front 49

Which hair cells receive about 90% afferent fibers?

Back 49

IHCs

Front 50

From how many IHCs does each auditory nerve receive input?

Back 50

one

Front 51

Within the nerve bundle leaving the cochlea, to what frequencies are the nerves in the middle tuned?

Back 51

low frequencies

Front 52

What are the two major functions of the OHC amplification?

Back 52

(Sensitivity and frequency selectivity)

Front 53

Which two hearing abilities will be affected by damages to the OHCs?

Back 53

Lose sensitivity and frequency selectivity will not be as sharp and lose low sounds first

Front 54

What is the major function of the IHCs

Back 54

Transduction from mechanic vibration to neural activity

Front 55

What is the major function of the IHCs

Back 55

Transduction from mechanic vibration to neural activity

Front 56

What happens to the hearing in a frequency region where the OHC are intact but the IHCs are gone?

Back 56

No hearing

Front 57

During sound stimulation, what causes the stereocilia to bend

Back 57

Relative motion between BM and TM)

Front 58

Why does the BM have the max response to low frequency tones near the apical end, and a max response to high frequency tones near the basal end?

Back 58

resonance

Front 59

What are the two arguments supporting that BM traveling wave is not the same kind of traveling wave as the travels on a long rope after a person shakes it at one end?

Back 59

If you cut it and it does not need to go away from its source)

Front 60

The relative motion between the TM and the BM leads to bending cilias

Back 60

which leads to depolarization

Front 61

Why is the Alternating Current component of the cochlear potential the “cochlear microphonic”?

Back 61

Because you can hook it up to a PA system

Front 62

What is the potential difference across the top of the hair cells between the inside and outside of the hair cells?

Back 62

150mV +80 -70

Front 63

List the major outer and middle ear structures (that are of functional importance) in the correct order from pinna to oval window.

Back 63

(Pinna, cocha, ear canal, tympanic membrane, three ossicles, oval/round windows; middle ear ligaments/ muscles; E. tube)

Front 64

What is the amount of the maximum boost in dB to the sound due to the ear-canal resonance?

Back 64

10-15dB

Front 65

What is the frequency of maximum boost due to the ear canal

Back 65

2-3 kHz

Front 66

What is the maximum boost in dB to the sound due to the concha resonance

Back 66

10 dB

Front 67

What is the frequency of that maximum concha resonance

Back 67

5 kHz

Front 68

What is the primary function of the middle ear?

Back 68

overcome impedance

Front 69

Describe the three middle-ears mechanisms that contribute to overcoming mismatch of impedance.

Back 69

Area 25 dB; lever 2 dB, buckling motion 6 dB

Front 70

What is the amount of the peak of max gain in DB that the middle ear transfer function shows?

Back 70

30 dB

Front 71

At what frequency does the middle ear transfer function show the max gain

Back 71

1000 Hz

Front 72

What is the primary function of the E tube

Back 72

Equalizing pressure

Front 73

Due to the presence of pinna, sounds coming from different directions will be affected differently upon reaching the eardrum. In which aspect does the pinna cause the sounds to change?

Back 73

Spectral shape

Front 74

During sound stimulation, what causes the stereocilia to bend?

Back 74

Relative motion between BM and TM)

Front 75

Boost due to sphere head
Why there is a boost?

Back 75

constructive interaction

Front 76

How many dBs is the boost for a sphere head?

Back 76

5dB

Front 77

What frequency region has the boost for sphere head

Back 77

> 500Hz

Front 78

How is it done localization?

Back 78

A change in the sound direction will cause a change in spectral shape, particularly at high frequencies

Front 79

What’re the limitations of the hearing protection that the middle-ear muscles can provide?

Back 79

Contraction in responding to loud sound to protect hearing
-reduction in transmission of loud sound by 10-30 dB

Front 80

Auditory (Eustachian) tube Audult vs. Infant

Back 80

Infant is more horizontal and leads to more ear infections.

Front 81

The Ossicles apply force to only one window

Back 81

oval window

Front 82

What’re the limitations of the hearing protection that the middle-ear muscles can provide?

Back 82

10 to 30 dB; only from very loud sound; slow to react

Front 83

Why is it important to pass the sound to only one window but not both oval and round window?

Back 83

cochlear fluid is incompressible, thus when one window is pushed in, the other window must be going out

Front 84

Describe how hair cells are positioned along the BM within the organ of corti.

Back 84

Three rows of OHCs and one row of IHC along the BM

Front 85

Organ of Corti

Back 85

Hair Cells: 3 rows of OHC 1 row of IHC. supporting hair cells. surrounded by tectorial membrane

Front 86

When a tone vibrates the stapes, how does the stapes stimulate each point along the BM?

Back 86

The stapes stimulates every point simultaneously

Front 87

Describe how OHC amplifies the BM response to sound

Back 87

1. The initial motion of BM will set off the OHC to dance
2. The OHC ‘dance’ pumps energy back into the BM and amplifies its motion
3. The enhanced BM motion is much more easily detected by the IHC

Front 88

What voltages are the three resting potentials?

Back 88

1. EP: +80 mV;
2. Intracellular: -70 mV;
3. extracellular: 0 mV

Front 89

What are stimulus evoked potentials?

Back 89

CM, ac; mostly from OHCs; it follows the stimulus frequency
SP, dc; from multiple sources

Front 90

Disturbance/motion OAE

Back 90

* originated on BM  vibration of cochlear fluid  vibrations of the ossicles and tympanic membrane  sound in the ear canal

Front 91

How many Type I fibers innervate each IHCs?

Back 91

many to one

Front 92

Where do efferent fibers make connections?

Back 92

directly on the OHCs, and indirectly via afferent fiber on the IHCs

Front 93

Inside the nerve bundle within the modiolus wall, how are the AN fibers organized according to their best frequencies?

Back 93

low-freq fibers in the center; high-frequency fibers on the outside

Front 94

What’s in a PST histogram?

Back 94

SOAR: spontaneous activity, onset response, adaptation, recovery

Front 95

Neural Rate-Intensity Function

Back 95

spontaneous rate, dynamic range= staturation - thershold

Front 96

Three Types of Neurons

Back 96

Low-SR (< 0.5 Spikes/sec): High thresh
Med-SR (0.5 <SR < 18 s/s): Med thresh
High-SR (> 18 s/s): Low thresh

Front 97

What is the limit for a nerve’s discharge rate?

Back 97

1000 spikes/sec

Front 98

Why is the discharge rate limited to 1000 S/s?

Back 98

because action potential has a refractory period of about 1 ms, during which no two spikes are allowed

Front 99

Tuning Curve

Back 99

place coding:A frequency to place mapping; each nerve carries info about a specific place or frequency

Front 100

Temporal

Back 100

: The temporal pattern of spikes (e.g., interval histogram) encodes stimulus frequency and pitch

Front 101

Place:

Back 101

The peak of the BM excitation, as reflected in the AN responses, encodes stimulus frequency and pitch