hearing

Question 1

why is endocochlear potential important

Answer 1

high conc. of K in endolymph allows for fast depolarization of the hair cell bodies which are surrounded by the perilymph (scala tympani)

Question 2

helicotrema

Answer 2

connects the scala vestibuli and scala tympani at the apex

Question 3

how do sound waves transduce through the cochlea

Question 4

which types of channels join the tip links to the hair cells

Answer 4

TRPA 1 mechanic potassium channels

Question 5

where are the stereocillia of the hair cells located

Answer 5

scala media (endolymph)

Question 6

where is the cell body of the hair cells

Answer 6

scala tympani (perilymph)

Question 7

describe transduction of hair cell depolarization

Answer 7

the movement of the basilar membrane causes hair cells in the stereocillia to move towards the tallest stereocillium, TRPA1 K channels open, the cell depolarizes, calcium channels downstream open, and neurotransmitter is released onto the spiral ganglion

Question 8

how do motor proteins help with cochlear amplification

Answer 8

DOUBLE CHECK: outer hair cells have motor proteins which compress/elongate onto the basilar membrane and stimulate it to initiate a response from the inner hair cell
-help with sound waves (regardless of frequency) which do not have a high enough intensity

Question 9

what are the two ways we decode auditory signals

Answer 9

phase locking and tonotophy/label lining

Question 10

what is the central auditory pathway

Answer 10

spiral ganglion, ipsilateral auditory nerve, ipsilateral and contralateral superior olive, inferior colliculus, medial geniculate thalamus, primary auditory cortex

Question 11

will a lesion below the superior olive cause binaural or monaural hearing loss

Answer 11

binaural

Question 12

will a lesion above the superior olive cause monaural or binaural hearing loss

Answer 12

monaural

Question 13

do the core regions play a significant role in distinguishing between sound wave frequencies from speech, environment, and music

Answer 13

no, only belt regions

Question 14

which cortical regions respond to speech

Answer 14

left belt (also right but less)

Question 15

which cortical regions respond to music

Answer 15

right belt mostly

Question 16

which cortical regions respond to the environment

Answer 16

both right and left but moreso right

Question 17

describe the MSO pathway

Answer 17

less than 2kHz; ; sound wave travels through both ears, ear closest to the sound fires action potential onto the ganglion cells/auditory nerve and reaches MSO. a little later, ganglion cells/auditory nerve from the farther ear also fires an action potential which travels to the MSO, at the coindicent neuron in the MSO, the largest signal is fired to the lateral geniculate nucleus

Question 18

describe the LSO pathway

Answer 18

-more than 2000Hz
-occurs when the frequency of one signal is too large to measure interaural time differences
-the intensity of the first signal is echoed the other ear
-signals from both ears synapse on the inhibitory MNTB
-MNTB inhibits the other ear with a signal corresponding to the amplitude in the ipsilateral ear
-these net signals are sent to the LSO
-only one signal will actually be sent to the LSO unless the signal is coming from an equidistant point from both ears

Question 19

how many genetic loci have been identified for hearing loss

Answer 19

300

Question 20

what are the names of the ossicles

Answer 20

stapes, incus, malleus

Question 21

infrasound

Answer 21

less than 20Hz

Question 22

ultrasound

Answer 22

more than 20kHz

Question 23

sound intensity for instant perforation of the eardrum

Answer 23

160dB

Question 24

the auditory canal acts as a __________, enhancing sounds between _________kHz

Answer 24

closed tube resonator, 2-5kHz

Question 25

compare the pressure of the oval window and tympanic membrane

Answer 25

the pressure at the oval window is 20x greater

Question 26

what is the purpose of the round window

Answer 26

decompresses the acoustic energy that enters the cochlea via the stapes against the oval window (i think it stops the cochlea from popping)

Question 27

attenuation reflex

Answer 27

when a loud sound (70-90dB) causes tympani and stapedius muscle to contract stopping movement of the ossicles

Question 28

endolymph

Answer 28

high potassium, low sodium, most positive potential

-scala media

Question 29

perilymph

Answer 29

high sodium, low potassium, lower potential than endolymph

-scala vestibuli and scala tympani

Question 30

where are hair cells located

Answer 30

organ of corti

Question 31

why is the helicotrema important/why do the scala vestibuli and scala tympani need to connect

Answer 31

allows for sound wave information to travel from the scala vestibuli to scala tympani so that basilar membrane can be stimulated/vibrated

Question 32

cochlea narrows from _______ to ________

Answer 32

base to apex

Question 33

basilar membrane widens from _________ to _________

Answer 33

base to apex

Question 34

stiffness of the basilar membrane decreases from _______ to ________

Answer 34

base to apex

Question 35

Broca’s aphasia

Answer 35

issues with language production but know what they want to say

Question 36

Wernicke’s aphasia

Answer 36

can speak but it does not come out coherently at all

Question 37

broadly speaking what is the left hemisphere imporant for

Answer 37

speech processing

Question 38

broadly speaking what is the right hemisphere important for

Answer 38

processing of tonal stimuli and music

Question 39

fun fact: we respond faster to speech than to music

Answer 39

did u know that cause that’s fun