EQUILIBRIUM AND AUDITION

Question 1

What part of the ear is the cochlea?

Answer 1

inner ear

Question 2

What is the pinna?

Answer 2

visible part of the outer ear

Question 3

What structures does the middle ear consist of?

Answer 3

tiny bones that connect tympanic membrane to inner ear

Question 4

Where is the tympanic membrane located?

Answer 4

separates outer and middle ear

Question 5

How is membrane potential defined?

Answer 5

inside relative to outside

Question 6

What are the two things that affect flow of ions across membranes?

Answer 6

• concentration gradient
• membrane potential

Question 7

What side of the hair cell does endolymph touch?

Answer 7

apical side of hair cells, where stereocilia are

Question 8

What is a key player in depolarization and repolarization of hair cells?

Answer 8

K+

Question 9

People can hear sounds up to how many Hz?

Answer 9

20,000

Question 10

Bats can hear sounds up to how many Hz?

Answer 10

100,000

Question 11

What is the stapes?

Answer 11

structure on oval window that include the last of 3 bones that vibrate against cochlea, near its base

Question 12

What is the cochlear base?

Answer 12

thinner, less flexible part of basilar membrane tuned for high frequencies

Question 13

What is the apex?

Answer 13

thicker, floppier part of basilar membrane tuned for low frequencies

Question 14

What type of coding does audition employ?

Answer 14

• labelled line coding
• temporal coding
• rate coding

Question 15

What does the shape of the ear give information about?

Answer 15

gives information on whether sound is in front or behind you – changes shape of sound wave as it enters ear canal, depending on whether sound is coming from the front or back

Question 16

Are pulses highly directional?

Answer 16

yes

Question 17

Have moths co-evolved with bats?

Answer 17

yes, and they have developed ears that can hear ultrasound

Question 18

Visual information is processed broadly in the brain – from retina to areas of the brain.

Answer 18

• eyes are part of central nervous system (CNS)
• lateral geniculate nucleus (LGN)
• striate cortex (V1 or primary visual cortex)

Question 19

Where are photoreceptors that respond to different colours?

Answer 19

intermingled in retina

Question 20

What is protanopia?

Answer 20

missing long (red) cone – cannot detect redness, red and green look very similar

medium (green) and long (red) cones have absorbance spectra that are fairly overlapping (they work together a lot) – if one of them is missing, can’t discriminate between colours in that range

Question 21

What is scotopic vision?

Answer 21

very lowest levels of light

• only rods are active – more sensitive
• below cone threshold

Question 22

What is mesotopic vision?

Answer 22

some ability to detect colours because cones are activated above this threshold – but it’s not great

Question 23

What is photopic vision?

Answer 23

indoor levels of light

• rods are saturated ∴ not giving much information
• relying much more heavily on cones ∴ have better colour vision

Question 24

Visual input is not evaluated on blank slate.

Answer 24

everything we see is process through frameworks that already exist in brain (ie. shadow affects overall brightness, but more importantly brain has evolved circuits to understand shadows)

Question 25

Which type of hair cell is more common?

Answer 25

stereocilia

Question 26

What do sounds consist of?

Answer 26

sinusoidal waves of air pressure changes – ie. tuning fork produces rippling changes in air pressure

Question 27

Flow into hair cells: endolymph vs. inner hair cells

Answer 27

• apical membrane potential of hair cells is -125 mV
• both have high K+ ∴ concentration gradient won’t do much
• large membrane potential ∴ K+ flows toward negative side into hair cells

Question 28

Flow out of hair cells: perilymph vs. inner hair cells

Answer 28

• basal membrane potential is -45 mV (lower electrical strength)
• large K+ concentration gradient drives K+ out of cell into perilymph, even if it’s against the electrical gradient

Question 29

Why isn’t loss of ability to hear high frequencies as we age not that important?

Answer 29

communication and much of what we use auditory system for is only a very small part of the range we can actually hear ∴ loss of high frequency detection in older adults does not affect day-to-day a lot

Question 30

What does the shape of the ear do?

Answer 30

gives info on if sound is in front or behind you – changes shape of sound wave as it enters ear canal

Question 31

What is the left LSO excited and inhibited by?

Answer 31

• excited by sound from left side
• inhibited by sound from right side

Question 32

What is the right LSO excited and inhibited by?

Answer 32

• excited by sound from right side
• inhibited by sound from left side

Question 33

How do bats escape bat echolocation?

Answer 33

moths often hear loud ultrasound pulses before bats can hear returning echoes ∴ can react with escape behaviour

moths jam bat sonar – produce high-pitched clicking sounds that interfere with echolocation
- as bat gets closer to moth, call frequency gets higher
- when far away from moth, bat just needs to know the general direction of moth location
- when closer to moth, bat needs to know exact moth location ∴ they increase call frequency to get more and updated information

clicking sounds from moth interfere with bat call frequencies
- bat call frequencies no longer increase reliably (speed varying) because bat is confused and unsure of target location