Hearing Flashcards
What neurotransmitters are involved in the IH Cell synapses?
Glutamate from AMPA Receptors.
Synchronised release.
What neurotransmitters are involved in the OH Cell synapses?
ACh, CGRP, ATP, GABA
The characteristic frequency and position upon the basal membrane is….
Logarithmic.
What is the pathway from the spiral ganglion to the auditory cortex?
Spiral ganglion, ventral cochlear nucleus, superior olive, Inferior colliculus, MGN, Auditory cortex.
What is phase locking?
Low frequency, firing every time.
What is the volley principle?
Neurons can’t follow every sound wave. Response is phase locked but not every cycle.
What is tonotopy?
Systematic organisation.
At high frequency, sound waves can produce…?
A sound shadow.
Interaural time delay is produced at which frequency?
Low Frequency
Interaural intenstiy difference is produced at which frequency?
High frequency
What happens when two impulses reach the same neuron?
An AP is initiated in the superior olivary nucleus.
In a Type EI (inhibitory neuron), what is the order of the contralateral, both ears and ipsilateral on the binaural graph?
Contralateral is the highest, then both ears then ipsilateral.
Where is Broadmann’s area 41 located in the brain?
The temporal lobe, low frequency at the anterior end and higher frequency at the posterior end.
Electrocochleography does what?
Measures the compound action potentials at the round window. Used in humans.
What is a BAEP?
Brainstem Auditory Evoked Potential. It has a small voltage (1-2uV)
What is incomplete deafness a result of?
Loss of outer hair cells (50dB of hearing loss)
What is complete deafness?
Loss of BOTH inner and outer hair cells. Hearing aids needed. Cochlea can’t respond.
What happens with aminoglycoside ototoxicity?
High frequency hearing loss.
First row of OH cells lost until completely lost.
Can lose IH cells.
What is noise trauma?
Can be temporary or permanent. Hair cells don’t regenerate. It’s not just about intensity but the duration also.
What is glutamate excitotoxicity?
NOISE -> depolarisation (excessive) -> Glutamate -> swelling and disruption -> synapse can recover. Calcium influx can lead to apoptosis.
Oxidative stress in the cochlea
Common factor is from hearing loss due to noise. Free radicals can damage DNA and trigger cell death.
What is Presbyacusis?
The deafness with aging.
