Efferent System

Question 1

What are the two main divisions of the efferent system? Which one do we know more about?

Answer 1

• Caudal –> know more about

- Rostral

Question 2

What are the 3 main feedback loops in the rostral portion? Which is the main auditory
processing loop?

Answer 2

• AC –> IC –> vMGB (main auditory processing loop)
• AC –> IC –> PTG
• AC –> SC –> MGB

Question 3

The neurons in the LOCB originate from where? Do they mostly have crossed or uncrossed
projections?

Answer 3

• LSO

- Uncrossed projections to the PVCN

Question 4

The neurons in the MOCB originate from where? Do they mostly have crossed or uncrossed
projections?

Answer 4

• MNTB, VNTB, DMPO, VMPO

- Crossed projections

Question 5

Describe the connections of MOCB fibers to IHCs and OHCs.

Answer 5

• IHCs: indirect

- OHCs: direct

Question 6

How do rate-intensity functions change with background noise? Noise + MOCB?

Answer 6

• Noise: suppression, increase in neural threshold for CF
• Noise+MOCB: increasing neural firing at high levels to try to overcome noise/return back to sharp/normal tuning and rate-level function

Question 7

What is the average change in threshold for an ANF with MOCB stimulation?

Answer 7

-15 dB reduction

Question 8

How does the cochlear microphonic change with MOCB stimulation?

Answer 8

-Enhanced

Question 9

How does the compound action potential change with MOCB stimulation?

Answer 9

-Suppressed

Question 10

How does the summating potential change with MOCB stimulation?

Answer 10

-Suppressed

Question 11

How does the endocochlear potential change with MOCB stimulation?

Answer 11

-6-7% reduction

Question 12

How does MOCB stimulation change hair cell polarization?

Answer 12

-Hyperpolarization