Auditory And Vestibular Systems

Front 1

Sense of hearing is for...

Back 1

Detecting sounds, perceive and interpret nuances

Front 2

Sense or balance is for...

Back 2

Head and body location, head and body movements

Front 3

What is sound?

Back 3

Audible variations in air pressure

Front 4

What is sound frequency?

Back 4

Number of cycles per second expressed in Hz

Front 5

What is one cycle?

Back 5

Distance between successive compressed patches

Front 6

Frequency range of human hearing:

Back 6

20-20,000 Hz

Front 7

What is intensity?

Back 7

Difference in air pressure between compressed and rarefied patches of air

Front 8

Auditory pathway stages:

Back 8

Sound waves

TM

Ossicles
Oval window

Cochlea fluid

Sensory neuron response

Front 9

Brainstem nuclei output

Back 9

thalamus to A1

Front 10

Middle ear: sound force amplification by the...

Back 10

ossicles

Front 11

Pressure:

Back 11

force by surface area; greater pressure at oval window than TM, moves fluid

Front 12

The acoustic reflex:

Back 12

Response where onset of loud sound causes tensor tympani and stapedius muscle contraction

Front 13

Function of AR:

Back 13

Adapt ear to loud sounds, understand speech better

Front 14

Perilymph:

Back 14

fluid in scala vestibuli and scala tympani

Front 15

Endolymph:

Back 15

fluid in scala media

Front 16

Endocochlear potential:

Back 16

endolymph electric potential 80 mV more positive than perilymph (perilymph is 0 mV)

Front 17

Pressure at the ______ window pushes ________ into scala vestibuli, ______ window membrane bulges out

Back 17

oval; perilymph; round

Front 18

Structural properties of the BM

Back 18

wider at apex

stiffness decreases from base to apex

Front 19

Research from Georg von Bekesy

Back 19

Endolymph movement bends BM near base, wave moves towards apex

Front 20

Sound causes...

Back 20

BM to move upward, reticular lamina up, and stereocilia bends outward

Front 21

Innervation of hair cells

Back 21

one spiral ganglion fiber, one inner hair cell, numerous outer hair cells

Front 22

Amplification by ______

Back 22

outer hair cells

Front 23

function of outer hair cells

Back 23

sound transduction

Front 24

motor proteins

Back 24

change length of outer hair cells

Front 25

prestin

Back 25

required for outer hair cell movements

Front 26

Auditory pathway has more _______ at nuclei and more alternative _________ than the visual pathway

Back 26

synapses; pathways

Front 27

Dominant pathway goes from...

Back 27

SOC to contra side (but still goes on ipsi side)

Front 28

Characteristic frequency of neurons in auditory pathway:

Back 28

frequency at which neuron is most responsive

Front 29

Response of neurons in auditory pathway:

Back 29

more complex and diverse on ascending auditory pathway in the brainstem

Front 30

Encoding info about sound intensity

Back 30

firing rates of neurons; number of active neurons

Front 31

Frequency sensitivity:

Back 31

basilar membrane

Front 32

Frequency

Back 32

highest at base, lowest at apex

Front 33

tonotopy:

Back 33

systematic organization of characteristic frequency within auditory structure

Front 34

Phase locking:

Back 34

Consistent firing of cell at same sound wave phase

Front 35

Techniques for sound localization:

Back 35

Horizontal (left-right), vertical (up-down)

Front 36

Localization of sound in horizontal plane

Back 36

ITDs, ILDs, duplex theory of sound localization

Front 37

ITD:

Back 37

time taken for sound to reach from ear to ear

Front 38

ILD:

Back 38

sound at HF from one side of ear

Front 39

Duplex theory of sound localization:

Back 39

ITD: 20-20,000 Hz

ILD: 2000-20,000 Hz

Front 40

The sensitivity of binaural neurons to sound localization:

Back 40

Monaural, binaural, superior olive

Front 41

Superior olive:

Back 41

cochlear nuclei input to superior olive, greatest response to specific interaural delay

Front 42

Acoustic radiation:

Back 42

axons leaving MGN project to auditory cortex via internal capsule in an array

structure of A1 and secondary auditory areas similar to corresponding visual cortex

Front 43

Neuronal response properties:

Back 43

frequency tuning; isofrequency bands

Front 44

Frequency tuning:

Back 44

similar characteristic frequency

Front 45

isofrequency bands:

Back 45

similar characteristic frequency, diversity among cells

Front 46

Principles in study of auditory cortex

Back 46

tonotopy, columnar organization of cells with similar binaural interaction

Front 47

Lesion in auditory cortex

Back 47

normal auditory function

Front 48

lesion in striate cortex:

Back 48

complete blindness in one visual hemisphere

Front 49

different frequency band information:

Back 49

parallel processing, localization deficit

Front 50

Importance of vestibular system

Back 50

balance, equilibrium, posture, head, body, eye movements

Front 51

Function of semicircular canals:

Back 51

detect head movements

Front 52

Structures of vestib system:

Back 52

crista, ampulla, cilia, kinocili, semicircular canals

Front 53

Crista:

Back 53

sheet of cells where hair cells of semicircular canals clustered

Front 54

Ampulla:

Back 54

bulge along canal, contains crista

Front 55

Cilia:

Back 55

project into gelatinous cupula

Front 56

Kinocilia:

Back 56

oriented in same direction so all excited or inhibited together

Front 57

Three semicircular canals on one side:

Back 57

-helps sense all possible head-rotation angles

Front 58

Each canal paired with...

Back 58

another on opposite side of head

Front 59

Push-pull arrangement of vestib axons:

Back 59

rotation causes excitation on one side, inhibition on the other

Front 60

Vestibulo-ocular reflex (VOR) function:

Back 60

line of sight fixed on visual target

Front 61

VOR mechanism

Back 61

senses rotations of head, commands compensatory movement of eyes in opposite direction

Front 62

connections from semicircular canals to....

Back 62

vestib nucleus, to cranial nerve nuclei --> excite extraocular muscles

Front 63

Hearing and balance have nearly identical ____

Back 63

sensory receptors (hair cells)

Front 64

Movement detectors:

Back 64

periodic waves, rotational, and linear force

Front 65

Auditory system:

Back 65

senses external environment

Front 66

vestib system:

Back 66

senses movements relative to gravity and environment

Front 67

auditory system parallels ______

Back 67

visual system

Front 68

how?

Back 68

tonotopy (auditory) and retinotopy (visual) preserved from sensory cells to cortex code

Front 69

convergence of inputs from lower levels -->

Back 69

neurons at higher levels have more complex responses