Auditory, Vestibular Systems

Front 1

Tonotopy: defn

Back 1

systematic representation of sound frequency along the length of the cochlea. Important organizational feature preserved throughout central auditory pathways.

Front 2

What's the first place that info from the two ears interacts?

Back 2

superior olivary complex

Front 3

selective hearing loss in the 2-5 kHz range disproportionately degrades what?

Back 3

speech recognition

Front 4

site where bones of middle ear contact inner ear

Back 4

oval window

Front 5

connect tympanic membrane to oval window

Back 5

ossicles (malleus, incus, stapes)

Front 6

Losses that lower the efficiency at which sound energy is transferred to inner ear

Back 6

conductive hearing losses

Front 7

hyperacusis

Back 7

painful sensitivity to sound. caused by paralysis of either tensor tympanic (CN V) or stapedius (CN VII)

Front 8

Losses due to damage of hair cells of inner ear or to auditory nerve itself

Back 8

sensorineural hearing losses

Front 9

T/F Auditory hair cells regenerate in humans

Back 9

F

Front 10

What do conventional hearing aids do?

Back 10

Used in conductive hearing loss to boost sounds to compensate for reduced efficiency of conductive apparatus

Front 11

T/F Conventional hearing aids are useless in sensorineural hearing loss

Back 11

T

Front 12

What is the defining symptom of peripheral hearing loss and why?

Back 12

Monaural hearing deficits, because unilateral damage at or above auditory brainstem leads to binaural deficits

Front 13

Two types of peripheral hearing loss

Back 13

Conductive or sensorineural

Front 14

Cochlear implants are useful for people with CN VIII damage

Back 14

F

Front 15

Describe mechanoelectrical transduction mediated by hair cells

Back 15

When hair bundle is deflected towards the tallest stereocilium, cation-selective channels open near tips, allowing K+ to come in and depolarize. Depolarization allows Ca2+ channels to open, causing release of neurotransmitter onto nerve endings of auditory nerve.

Front 16

What are the two sound localization functions the human auditory system uses?

Back 16

1) Interaural time differences
2) Interaural intensity differences

Front 17

T/F Even at the level of the brainstem, info from each ear reaches both sides of the system

Back 17

T

Front 18

Interaural time differences are processed in the __________

Back 18

medial superior olive

Front 19

Interaural intensity differences are processed in the __________

Back 19

lateral superior olive

Front 20

preferred horizontal location

Back 20

azimuth

Front 21

part of thalamus that is obligatory relay for all ascending auditory information destined for cortex

Back 21

medial geniculate complex

Front 22

location of primary auditory cortex/A1

Back 22

Superior temporal gyrus

Front 23

area critical to comprehension of human language in secondary auditory area

Back 23

wernicke's area

Front 24

For high frequency sounds, the amplitude of the traveling wave reaches a max at ____ of cochlea while low frequency sounds reach max at ______ of cochlea

Back 24

base ; apex

Front 25

Which bone touches the oval window?

Back 25

Stapes

Front 26

ribbon of sensory
epithelium which runs
lengthwise down the
cochlea's entire scala
media. Its hair cells
(15,000-20,000)
transform the fluid
waves into nerve signals

Back 26

organ of Corti

Front 27

Scala vestibuli and tympani filled with ___________; the scala media filled with __________. **** know this.

Back 27

paralymph; endolymph (they have slightly different ionic concentration). Para is more like CSF; endolymph more like ICF.

Front 28

Top membrane of cochlea

Back 28

tectorial

Front 29

bottom membrane of cochlea

Back 29

basilar

Front 30

What do the outer hair cells do?

Back 30

They receive efferent input from the superior olive which causes them to stretch out. Result is <b>amplification of sound.</b>

Front 31

Basilar membrane is thin and stiff at base which receives _____ frequencies; relatively more flexible and wider at apex to receive ____ frequencies.

Back 31

high;low

Front 32

T/F Vertical movement of the basilar membrane translates into a shearing
force that bend the stereocilia of the hair cells.

Back 32

T. There is an upward and a downward phase.

Front 33

Endolymph has _____ K+ than the perilymph, leading to what?

Back 33

more. Leads to setting up an electrochemical gradient that favors the movement of K+ into the cell when the cation channels open.

This leads to depolarization, which leads to NT release.

Front 34

How is the tonotopic map maintained past the cochlea?

Back 34

The hair cells interact with auditory nerve fibers in a 1-to-1 ratio.

As a result, auditory
nerve fibers related to the apical end respond to low frequencies and visa versa.

Front 35

How does the Medial Superior Olive (MSO) compute the location of a sound by interaural time differences?

Back 35

Sound arrives at different times in the two ears so that the resultant nerve
impulses arrive at a particular MSO neuron simultaneously, making
each cell especially sensitive to sound sources in a particular space.

Front 36

condition in which the ossicles of the middle ear become
immobile because of growth of the surrounding bone

Back 36

otosclerosis

Front 37

Otoacoustic emission

Back 37

inaudible sounds (produced by the hair cells) generated from the
cochlea when audible sound stimulates the cochlea.

Front 38

How does otoacoustic emission testing work?

Back 38

Persons with normal hearing produce otoacoustic emissions. Those with hearing loss greater
than 25-30 dB do not.

Front 39

What is auditory brainstem response testing?

Back 39

An auditory evoked potential that originates from the auditory nerve.
Electrodes on the head measure brain wave activity in response to sound.
ABR assesses the auditory pathway from periphery to brainstem.

Front 40

What does the labyrinth consist of?

Back 40

3 semicircular canals plus the otolith organs (utricle and saccule)

Front 41

Specialized to primarily respond to linear accelerations and static head position

Back 41

utricle and saccule

Front 42

Specialized to respond to rotational accelerations of the head

Back 42

semicircular canals

Front 43

what kind of fluid are the membranous sacs within the bone/mebranous labyrinth filled with?

Back 43

endolymph (high in K+, low in Na+)

Front 44

What kind of fluid is between the bony walls (osseous labyrinth) and membranous labyrinth?

Back 44

perilymph (low in K+, high in Na+)

Front 45

What are the ampullae?

Back 45

The juglike swellings at the base of the semicircular canals. Where vestibular hair cells are located.

Front 46

What is the macula?

Back 46

Sensory epithelium of the otoliths, consists of hair cells and supporting cells

Front 47

What are otoconia?

Back 47

Embedded crystals of CaCO3. They make the otolithic membrane they're embedded in heavier than structures and fluids surrounding it, thus, when head tilts, gravity causes membrane to shift relative to sensory epithelium

Front 48

What is the striola?

Back 48

specialized area in the utricle and saccule that divide the hair cells into two populations with opposing polarities

Front 49

What is a normal person's response to irrigating one ear with cold water?

Back 49

1) SLOW movement TOWARD irrigated ear

2) FAST movement AWAY

Front 50

COWS

Back 50

(cold opposite, warm same) - for determining which direction the fast movement should be

Front 51

What is a person with a cerebral hemisphere dysfunction's response to irrigating one ear with cold water?

Back 51

ONLY the slow movement component of the eyes to side of irrigated ear

Front 52

utricle and saccule ONLY respond to what?

Back 52

linear acceleration

Front 53

semicircular canals only respond to what?

Back 53

angular acceleration

Front 54

the direction of depolarizing deflection is (toward, away from) the kinocilium

Back 54

toward

Front 55

the direction of hyperpolarizing deflection is (toward, away from) the kinocilium

Back 55

away from

Front 56

How does gravity cause the stereocilia to move towards the kinocilia?

Back 56

the calcium crystals are heavier and affected by gravity. when it moves in a particular orientation they create a dragging force along the macule

Front 57

where and what is the cupula?

Back 57

located within the ampullae of each of the three semicircular canals.

It's a gelatinous mass that is a barrier thru which endolymph can't circulate. as a result it gets distorted by movement of the endolymphatic fluid.

Front 58

what activates the cupula?

Back 58

dragging the hair thru the fluid and bending the cupula

Front 59

A counterclockwise rotation to the Left side causes the endolymph (thru inertia) to move right. the cupula gets displaced such that the ____ side is stimulated.

Back 59

L side. R side gets hyperpolarized.

Front 60

When you slowly rotate head to right, what is slow and fast nystagmus direction beat?

Back 60

First it's slow to LEFT. then the fast beat is to right.

Front 61

T/F vestibular fibers innervating otoliths and semicircular canals exhibit a high level of spontaneous activity

Back 61

t

Front 62

Vestibular nerves arise from a population of bipolar neurons, the cell bodies of which reside in ___________

Back 62

vestibular nerve ganglion/scarpa's ganglion

Front 63

Where do the proximal / central processes of the vestibular nerve ganglia synapse?

Back 63

In the <b>medial and lateral vestibular nuclei</b>

Front 64

Where do the fibers from medial vestibular nuclei project?

Back 64

excitatory fibers cross to the contralateral abducens nucleus; Inhibitory neurons project from medial vestibular nucleus to left abducens nuclear.

Front 65

Where do fibers originating in the abducens nucleus project?

Back 65

there are two outputs. One is motor (causes lateral rectus in contralateral eye to contract); the other is an excitatory projection that crosses the midline and ascends via the medial longitudinal fasciculus to the left oculomotor nucleus, where is activates neurons of the ipsilateral side and contracts the medial rectus.

Front 66

what is medial longitudinal fasciculus?

Back 66

It is a tract that fibers traveling from abducens nuclei to oculomotor nucleus use. while traveling in it, fibers cross the midline, such that the oculomotor nucleus they synapse on is CONTRALATERAL to the abducens nucleus they are arising from.

Front 67

Site where the fibers arising from the abducens nucleus to innervate oculomotor nucleus cross

Back 67

medial longitudinal fasciculus

Front 68

What is the vestibulo-ocular reflex?

Back 68

A rotation of the head is detected, which triggers an inhibitory signal to the extraocular muscles on one side and an excitatory signal to the muscles on the other side. The result is a compensatory movement of the eyes.

Front 69

what mediates postural adjustments of the body?

Back 69

vestibulo-spinal reflex

Front 70

What happens in vestibulo-spinal reflex (VSR?)

Back 70

Inputs from otoliths project to lateral vestibular nucleus which sends axons in the lateral vestibulospinal tract to the spinal cord. these axons terminate on extensor motor neurons