Lecture 14

Question 1

where do cochlea implants electrically stimulate

Answer 1

The neurons in the cochlea (the number of neurons doesn’t change in deafness)

Question 2

when is a cochlea implant necessary

Answer 2

severe sensorineural hearing loss. i.e. little to no hair cells in the cochlea

Question 3

what is lost first in sensorineural hearing loss

Answer 3

OHC

Question 4

Four main degenerations of the cochlear

Answer 4

1. loss of hair cells (flattening of organ of corti)
2. loss of peripheral processes (site of AP)
3. loss of SGN (spiral ganglion neurons)
4. Reduction in SGN cell body size and myelin

Question 5

where is a cochlea implant inserted?

Answer 5

Into scala tympani through round window or drilled hole in cochlea

Question 6

modes of hearing loss

Answer 6

Ototoxic agents (“mycins”)
Noise induced hearing loss
Presbycusis (age)

Question 7

Hair cell loss implication

Answer 7

no afferent drive/depolarisation

Question 8

Peripheral process loss Implication

Answer 8

site of action potential generation is central to soma (along central axon)

Question 9

demyelination of SGNs implication

Answer 9

reduces the efficiency of the neuron to respond to electrical stimulation

Question 10

reduced number of SGNs implication

Answer 10

may be a contributing factor (but not the sole factor) affecting CI (cochlea implant) performance (absolute number required TBC)