Auditory Mechanism (College of DuPage) Flashcards
Abbreviations: CO, AN, IAM, CN, SOC, LL, IC, MGB, int cap, AC, CC
cochlea, auditory nerve, internal auditory meatus, cochlear nucleus, superior olivary complex, lateral lemniscus, inferior colliculus, medial geniculate body, internal capsule, auditory cortex, corpus callosum
Auditory system performs two kinds of processing of acoustic stimuli
Sequential and parallel processing
Sequential processing takes place in the __. Parallel processing takes place in the __
Entire auditory system; neural system
Involves the transferring of information from one area or a level of the auditory system to the next
Sequential processing
Involves overlapping functions that occur at the same time along different channels
Parallel processing
Both of these types of processing are needed for optimal functioning of the auditory system
Sequential and parallel processing
Auditory nerve has type one and type two fibers that proceed in __ to the brain stem
Parallel
Retrocochlear
All structures beyond the cochlea
The temporal bone has many __, __, and __ that subserve the organs of hearing and balance
Cavities, channels, and canals
Temporal bone has four main segments
The squamous, mastoid, petrous, Tympanic
The squamous is __ to the ear canal
Superior
The mastoid is __ to the pinna
Posterior
The petrous is deep in the __ __ of the inner ear
Cranium housing
Petrous segment is where the __, __, __ and __ are located
Middle ear apparatus, cochlea, vestibular structures, IAM
IAM houses the __, __, and __ nerves and opens into the lateral aspect of the __
IAM houses the FACIAL, AUDITORY and VESTIBULAR nerves and opens into the lateral aspect of the BRAINSTEM
Scala tympani and scala vestibuli contain
Perilymph
Scala media contains
Endolymph and cortilymph
Tectorial membrane touches the cilia of
OHC
Tectorial membrane does Not touch the
IHCs
This is at the base of stereocilia, forms a tight juncture around Celia also prevents endolymph from entering the hair cells
Reticular lamina
Known as ’support cells’
Deiter’s cells
Described as having an elongated body, spanning from the BM to the reticular lamina, and holding the base of the OHCs
Deiter’s cells
One row, flask shaped, robust
IHCs
3 to 5 rows, cylinder shaped thin and long
OHCs
How many IHCs per ear
3500
How many OHCs per ear
12,000
Stereocilia are at the top of the hair cell. At the bottom are AN fiber connections called
Terminal buttons
Tip links close the __ in __
Tip links close the PORES in CILIA
When the BM moves downward, tip links close the pores in cilia causing
hyper-polarization (inhibition)
When BM moves upward, cilia are pushed opposite way and tip-links open cilia pores causing K+ to enter the cell then
The cells fire (depolarization)
90% of auditory nerve fibers are type __ fibers, and they synapse with IHCs. Extensive projections to Cochlear Nucleus
1
The frequency that an auditory nerve responds best to (lowest intensity bc it doesn’t take much energy to get a response)
Characteristic frequency
The further away the tone is from the characteristic frequency the more __ will be needed
Intensity
The sharper the tuning curve the better the __ __ is
Frequency selectivity
Damage to OHCs decrease in __ of tuning curve
Sharpness
Auditory nerve fiber can only fire at a rate of __ times per __ (unable to fire at a higher rate for Phase locking)
1000 times per second
Principle that states with high frequency sounds the auditory nerve fibers may fire every second third or fourth cycle of stimulus
Volley
__ is coded by how many fibers are involved
Intensity
When fibers have a low spontaneous rate they are better at coding __ intensities
High
When fibers have a high spontaneous rate they are better at coding __ intensities
Low
Phase locking is for coding __ and hair fibers are for coding __ for the brain
Frequency; intensity
Corpus callosum
Nerve tract that runs beneath the cerebral cortex. It connects L hemisphere of brain to the R hemisphere. “Tough body”
10% of auditory nerve fibers are type __, unmyelinated, and they synapse with OHCs. Limited projections to Cochlear Nucleus.
2
Hair bundles, or the “__ __” of hair cells, are important in cochlear tonotopy. The morphology of hair bundles likely contributes to the BM gradient. Tonotopic position determines the structure of hair bundles in the cochlea. The height of hair bundles __ from base to apex and the number of stereocilia __
Hair bundles, or the “MECHANICAL ANTENNA” of hair cells, are important in cochlear tonotopy. The morphology of hair bundles likely contributes to the BM gradient. Tonotopic position determines the structure of hair bundles in the cochlea. The height of hair bundles INCREASES from base to apex and the number of stereocilia DECREASES
In the hair bundle, ___ springs determine the open probability of mechanoelectrical ion transduction channels: at higher frequencies, these elastic springs are subject to higher stiffness and higher mechanical tension in tip-links of hair cells.
GATING
currents are largest at high frequency positions at the base of cochlea. basal cochlear hair cells have more stereocilia, thus providing more __ and larger __ (and the base of the cochlear is closer to the outer ear)
currents are largest at high frequency positions at the base of cochlea. basal cochlear hair cells have more stereocilia, thus providing more CHANNELS and larger CURRENTS (and the base of the cochlear is closer to the outer ear);
outer hair cells express the __ protein prestin and they’re also known as little __ __ that amplify __ __ __.
outer hair cells express the MOTOR protein prestin and they’re also known as little COCHLEAR AMPLIFIERS that amplify LOW-INTENSITY SOUNDS.
