Retrocochlear Mechanism
What is stimulated for sensorineural hearing to be activated?
The cochlea
Where is the primary auditory cortex located?
Heschl's gyrus, BA 41-42
What are the "true sensory receptors"?
Inner hair cells
Frequency representation in the cochlea for the responsivity of specific hair cells.
Tonotopicity
Type of hearing loss characterized by a reduction in hearing sensitivity due to a problem in the outer and/ or middle ear.
Conductive
What/ where are the 1st order neurons of the ascending retrocochlear pathway?
The bipolar cells of the spiral ganglion
What is the correct order of the central auditory pathway?
Cochlea->SOC (decussation)->LL->IC->MGB->PAC (primary auditory cortex)
Active amplifiers that sharpen frequency selectivity
Outer hair cells
Individual neurons (can/cannot) keep up with the high frequencies in the cochlea.
Cannot
Damage beyond the cochlea.
Retrocochlear
What/ where are the 2nd-order neurons of the ascending retrocochlear pathway?
The dorsal and ventral cochlear nuclei of the medulla
What is Fx of the descending auditory pathway?
Enhancing signal-to-noise ratios in noise, selective attention, protective reflexes (auditory reflex via stapedius)
In the cochlea, K+ ions influx into the-
Endolymph
Which type of spiral ganglion neuron makes up 95% of the 30,000 total?
Type 1 (innervate the inner hair cells)
A controversial disorder in audiology (some don't think it's a real disorder), characterized by issues in processing and comprehending auditory information.
Auditory processing disorder (APD)
The combined auditory/ vestibular nerve fibers enter the brainstem and synapse (ipsilaterally/contralaterally) in the cochlear nuclear complex.
Ipsilaterally
The first point of auditory signal decussation in the brain occurs in the-
Superior olivary complex
In tonotopicity, high frequencies of the cochlea are located near the-
Base
What is the spiral ganglion?
A structure housing the cell bodies of the first-order neurons, receiving info from hair cells in the organ of corti.
What is the difference between binaural integration deficits and auditory closure deficits?
Binaural integration: combining auditory information from both ears
Auditory closure: filling in the gaps of missing speech elements
What/ where are the 3rd-order neurons of the ascending retrocochlear pathway?
Found in the superior olivary nuclei (SOC) and the lateral lemniscus nucleus (LL)
Where is the auditory association cortex?
Wernicke's area, BA 22
In the auditory system, action potentials are sent through the what?
Auditory nerve
The intensity of a frequency perceived is determined by the-
Number of stimulated neurons/ axons involved.
What are the 4 nuclei in which auditory action potentials are generated? Hint: they can be picked up by electrodes placed on the scalp.
CN (cochlear nucleus), SOC (superior olivary complex), LL (lateral lemniscus), IC (inferior colliculus)