lecture 6

Question 1

processing of natural sound

Answer 1

brain discriminates info from a mixed up sound and sepearted out in the cortex

Question 2

auditory nerve (VIII)

Answer 2

carries neuronal information from IHC - connects to multiple spiral ganglion and sends to cochlear nucleus

Question 3

ribbon synapses

Answer 3

hair cells rely on ribbon synapses
- depolarization caused by opening of MTC causes influx of Ca and release of vesicles
vesicles are organized around a ribbon

Question 4

otoferlin gene

Answer 4

contains many genes for deafness

• see in IHC
• important in transmisison of signal from hair cells to spiral ganglion
• brainstem response is absent in knockout mice

Question 5

what happens to Ca triggered exocytosis in otoferlin KO

Answer 5

exocytosis is abolished

• ability to cause increase in capacitance is gone and no vesicle release
• can increase capacitance by increasing SA or cage calcium

Question 6

otoferlin and Ca

Answer 6

calcium sensory -

otoferlin is important in sensing calcium coming in- most neurons use synaptotagmin

Question 7

pachanga mouse model

Answer 7

mutation in Otof leading to partiel loss of function

• normal hair cell transduction and receptor potentials but have severe hearing impariments
• transmission to spiral ganglion cell is warped

Question 8

3 components of electrocochlearagraphy

Answer 8

measures stimulus related cochelar potentials

1. cochlear microphonics : OHC
2. summating potentials: IHC
3. compound action potentials: Auditory Nerve

Question 9

pachanga in vesicle release

Answer 9

• showed that you can still see vesicle release but to a lower extent, pachanga acts on relasable pool and doesnt allow to be recycled so cannot continue to release
• argued otof isnt Ca sensor but helps recycle vesicles

Question 10

otoferlin as multifaceted Ca sensor

Answer 10

similar to snare - sensor of Ca

important in release- clears material from vesicular release site

Question 11

temperature dependant deafness

Answer 11

patients have hearing loss with a fever

Question 12

high frequencies an iHC

Answer 12

higher tones cant keep up and you see fusing

• brain doesnt need to follow stimulus to convey information
• basilar membrane of cochlea discriminates freq

Question 13

phase locked response of ANF

Answer 13

for every cycle there is a burst of AP

Question 14

3 divisions in cochlear nucleus

Answer 14

each ANF innervates all 3 CN divisions

• antereoventral CN (AVCN)
• postereoventral CN ( PVCN)
• dorsal CN (DCN)
• saw that there is cochleotopic organization of CN

Question 15

what is the connection from auditory nerve to bushy cells

Answer 15

end bulb of Held

• bushy cells show improved precision of phase locking
• fidelity of firing is tronger downstream then it is upstream

Question 16

cell types in VCN

Answer 16

spherical / globular bushy
stellate/multipolar
octopus cells
granule cells

Question 17

discharge patterns in the CN

Answer 17

• much more complexity than auditory nerve fiber
• can respond both tonic and phasic to a tone
• discharge patterns shaped by time dependant interactions of excitation and inhibition

Question 18

lateral inhibition - two tone suppression

Answer 18

tone elicits certain response
second tone in + area increases firing rate
second tone in - area decreases firing rate

Question 19

auditory pathway

Answer 19

cochlear nucleus –> superior olive –> inferior colliculus–> MGN–> auditory cortex

Question 20

organization in cortex

Answer 20

maintains tonotopic organization

- can see frequencies in diff locations

Question 21

cortical cells

Answer 21

tuned to precise sequence of complex sounds

- ethologically important sounds

Question 22

primary language areas of the brain

Answer 22

brocas: important for creating speech
lesion- understand language but cant produce speech
wernickes: how we understand speech
lesion- can speak but cannot understand