051 Central Auditory processing 2

Question 1

Which type of cochlear nerve fibres synapses with IHC?

Answer 1

Type I -> detection of sound

one to one mapping

Question 2

Which type of cochlear nerve fibres synpase with outer hair cells?

Answer 2

Type II -> amplification and tuning

many to one

Question 3

What is the coding range?

Answer 3

The range of sound intensity that a auditory fibre will signal. High spontaneous rate fibres will have a lower range for lower input intensities compared to low spontaneous rate fibres.

Question 4

Where are the 2 cochlear nuclei found and what are their separate functions?

Answer 4

Dorsal cochlear nuclei: complex sounds

Ventral cochlear nuclei: simple sounds

Question 5

Where is the 1st point of convergence of information from the 2 ears?

Answer 5

Superior olivary nucleus –> binaural hearing

Question 6

Which part of the olive is repsonsible for interaural level differences?

Answer 6

Lateral superior olivary nucleus

Question 7

Which part of the olive is responsible for interaural timing differences?

Answer 7

Medial superior olivary nucleus

Question 8

What occurs when tracking interaural level differences?

Answer 8

fibres from the opposite ear will invert Glutamate to glycine in the medial nucleus of the trapezoid body, causing less excitation of the LSO.

Question 9

What occurs when tracking interaural time differences?

Answer 9

due to phase locking, the ear further from the sound will cause inhibition delays at the post synaptic potential.

Question 10

Where is the site of convergence from ascending and descending pathways?

Answer 10

Inferior colliculus

Question 11

Which frequencies is the dorsal & lateral inferior colliculus responsible for?

Answer 11

Low frequencies - binaural

Question 12

Which frequencies is the ventral & medial inferior colliculus responsible for?

Answer 12

High frequences - binaural

Question 13

What is the role of the superior colliculus?

Answer 13

Integrating visual input with auditory input
Contains the only map of auditory space in the brain.
Rostral and medial –> high in elevation sounds and close to midline.
Caudal and lateral –> low in elevation sounds and lateral to midline.

Question 14

What does the median MGN do?

Answer 14

Duration and intensity, auditory attention and arousal

Question 15

What does the dorsal MGN do?

Answer 15

Plasticity and learning of sounds - most complex

Question 16

What does the ventral mGN do?

Answer 16

Sends information to the primary auditory cortex

Question 17

Where is the primary auditory cortex located?

Answer 17

In the Heschl’s gyri of the temporal lobe.

Question 18

Describe the specialization of hemispheres in terms of auditory processing?

Answer 18

Right hemisphere is for pitch direction

Left hemisphere is for suond duration

Question 19

Describe the olivo-cochlear efferent system to the inner and outer hair cells?

Answer 19

Lateral superior olive sends fibres to inner hair cells to influence the firing of auditory nerve fibres.

Medial superior olive sends fibres to outer hair cells to influence the amplification for different frequencies.