Hearing Part 2

Question 1

What are the 3 scalae?

Answer 1

Scala vestibuli
Scala media
Scala tympani

Question 2

What is the perilymph?

Answer 2

• fluid in Scala vestibuli and tympani

- composition: low K and high Na+

Question 3

What is the Endolymph?

Answer 3

Fluid in Scala media

Composition: high K and low Na+

Question 4

What does the Stria vascularis do?

Answer 4

Pumps K+ into Scala media

Question 5

Where is sound transduction performed?

Answer 5

In the Organ of Corti

Question 6

What does the cochlea do?

Answer 6

… breaks incoming complex sounds down into their component frequencies

Question 7

What is the name of the hairs on the organ of Corti?

Answer 7

Stereocilia

Question 8

What is the name of the tallest stereocilia?

Answer 8

Kinocilium

Question 9

What causes the movement of Stereocilia?

Answer 9

Displacement of basilar membrane

Question 10

Which movement depolarized hair cell?

Answer 10

Movement of Stereocilia towards the kinocillium

Question 11

…Hyperpolarizes?

Answer 11

Movement away from kinocillium

Question 12

How are the mechanically-gated channels on the Stereocilia connected with one another?

Answer 12

… by elastic filaments called “top links”

Question 13

What happens in the hair cell once the cell is depolarized?

Answer 13

• voltage gated Ca++ channels open
• Ca++ triggers release of neurotransmitter
• therefore 8th nerve afferent is depolarized

Question 14

What happens when the cell membrane potential Fluctuates?

Answer 14

Prestin molecules expand and contract

Question 15

In time, as the Preston molecules exp and contr, what happens to the cell itself?

Answer 15

It expands and contracts

Question 16

What happens when the cell exp and contract?

Answer 16

The basilar membrane moves, amplifying it’s movements

Question 17

What inactivâtes prestin?

Answer 17

Furosemide

Question 18

What must the auditory system encode? 3

Answer 18

• frequency of sound
• intensity of sound
• location of sound

Question 19

Upon what principe does frequency coding rely?

Answer 19

Phase locking or Volley principle

Question 20

What Is phase locking?

Answer 20

Same response on the same spot of each cycle

Question 21

How is intensity of sound coded? What are the two ways?

Answer 21

• increase firing rate

- increase #of active neurons

Question 22

In the columnar organization of the auditory cortex, what is the composition?

Answer 22

• isofrequency bands: analysis of sound frequency

- binaural bands: analysis of sound location

Question 23

What are the two types of superior olives?

Answer 23

Lateral and medial

Question 24

Which cells are in the MSO? What are they responsible for!

Answer 24

EE cells, for time delays

Question 25

Which cells are in the LSO? What are they responsible for?

Answer 25

EI cells, location: excitation from one side and inhibition