week 9 - audition: hearing and the brain

Question 1

In an overview, what is the order of the auditory cortex?

Answer 1

1. vestibulocochlear nerve
2. cochlear nerve
3. inferior colliculus
4. medial geniculate nucleus
5. A1

Question 2

primary auditory cortex (A1)

Answer 2

• on an area called the superior temporal cortex
• receives input fromt the medial geniculate complex; thus, it contains a precise tonotopic map

Question 3

What did researchers find in monkeys’ primary cortices?

Answer 3

• figured out what neurons respond best to by measuring frequencies
• developed the tonotopic map

Question 4

tonotopic map

Answer 4

low frequencies towards anterior and high frequencies towards posterior

Question 5

What do pitch neurons respond to?

Answer 5

• preferred frequency/tone
• complex sounds
• harmonics
• unusual sounds
• changes in sounds

Question 6

complex sounds

Answer 6

dominant tone of a sound is associated with the neuron which activates firing

Question 7

harmonics

Answer 7

relation to dominant tone

Question 8

What is the A1 responsible for?

Answer 8

perceiving pitch and simple sounds

Question 9

What is the core area responsible for?

Answer 9

locating sound

Question 10

What is the belt area responsible for?

Answer 10

locating sound

Question 11

What are the surrounding areas of the A1?

Answer 11

• core area
• belt area
• parabelt area

Question 12

In what ways are sounds perceived and grouped?

Answer 12

• location
• proximity in time
• good continuation
• similarity

Question 13

Jeffress Model: narrowly tuned ITD neurons

Answer 13

receive signals from both ears

Question 14

neural coincidence detectors

Answer 14

activated when they receive signal from both ears at the same time

Question 15

partial neural coincidence detectors

Answer 15

detect difference in hearing based on how fast/slow the signal is received from each ear

Question 16

barn owls and ITD

Answer 16

• evidence in support of Jeffress Model
• good at locating sound because their ITD neuron activation is very narrow which leaves less room for time difference
• specificity coding

Question 17

gerbils and ITD

Answer 17

• more bass heavy/broad in comparison to owls
• indicates that we are likely to be using distributed coding to measure time difference

Question 18

distributed coding

Answer 18

all neurons in an area respond to a sound

Question 19

How do hemispheric differences play a role in audition?

Answer 19

• we have neurons that respond to the contralateral side of the body
• right hemisphere responds to sound from the left and vice versa

Question 20

What does lesioining in the A1 cause?

Answer 20

decrease in ability to localize sound but not eliminated

Question 21

What happens when you cool the A1?

Answer 21

poor localization

Question 22

How did the A1 compare/differ from belt neurons

Answer 22

belt neurons provided more a more precise location

Question 23

What are the auditory pathways?

Answer 23

• ventral stream
• dorsal stream

Question 24

ventral stream

Answer 24

• determines what the sound is
• starts from the front portion of A1 and ends toward prefrontal cortex

Question 25

dorsal stream

Answer 25

- determines where the sound is located - starts from the back portion of A1 and goes toward parietal and prefrontal cortices

Question 26

What does damage to the temporal lobe cause?

Answer 26

inability to recognize what the sound it

Question 27

What does damage to the frontal lobe cause?

Answer 27

inability to localize the sound

Question 28

conductive deafness

Answer 28

- middle ear deafness - damage to any part of the middle ear can cause inability to conduct sound information to inner ear

Question 29

tympanic membrane

Answer 29

moves at the same vibration of sound and must be able to move fluid in the inner ear

Question 30

What is the treatment for conductive deafness?

Answer 30

hearing aids that raise volume in order to increase vibrations of middle ear

Question 31

nerve deafness

Answer 31

- inner ear deafness - damage to cochlea/cochlear nerve

Question 32

What happens when the cochlea is damaged?

Answer 32

action potentials on the cochlear nerve cannot travel up to the brain

Question 33

How can nerve deafness be treated if the cochlea is damaged but not the cochlear nerve?

Answer 33

cochlear implants can bypass the cochlea by having an external portion pick up external frequencies and an internal portion send electrical stimuli straight to the cochlear nerve

Question 34

What does damage to the A1 cause in regards to hearing loss?

Answer 34

results in the inability to tell differences in frequencies (amusia)