Auditory 1-3 Flashcards
what are the 3 compartments of the cochlea?
the scala vestibuli,
the scala media,
the scala tympani
The fluid filled scala vestibuli is connected to
the scala tympani by the ________
helicotrema (a hole in the BM located at the apex of the cochlea)
During an oscillatory sound wave the BM move up towards the ______ during rarefaction and down
towards the ______ during compression.
scala vestibuli,
scala tympani
A collapse of the
endocochlear potential due to a mutation in the gap junction subunit ______, which is important in active transport of potassium in the ______ , is the major cause of congenital deafness
connexin 32, stria vascularis
~28,500 Type I Auditory Nerve fibers (ANFs) innervate_____. This occurs because _____ Type I ANFs innervate a single IHC.
~3,500 Inner Hair Cells (IHC), 10-30
OHCs respond to changes in voltage with a change in length – they are _______
“electromotile”
The mechanical amplification of the displacement of the BM by OHCs is called the _________.
cochlear amplifier
Ototoxic antibiotics, such as _______, can block the transduction channel of the OHCs and, with prolonged action, can kill them resulting in deafness
streptomycin and gentamycin
For periodic stimuli, such as low-frequency pure tones, ANFs ______their action potentials in that the neurons tend to fire action potentials only at particular phases (i.e., compression or rarefaction) of the ongoing sound waveform
“phase lock”
An unusual type of sensorineural hearing disorder (not necessarily accompanied by hearing loss) called _______results from some problem with neural transmission from IHC to ANFs, or in the ANF function itself.
auditory neuropathy
What are the 3 main acoustical cues for sound source localization
1) Interaural time delays (ITDs) :because the ears are physically separated in space by the head. The source will generate different times of arrival of the sound at the two ears, or ITDs.
2) Interaural level differences (ILDs): The head becomes an obstacle. For sounds of high frequency ( the head essentially creates an “acoustic shadow” for the far ear as sounds with wavelengths on the order of the diameter of the head and smaller are reflected off the near side of the head. As expected, ILDs are small in magnitude for low frequency sounds and increase in magnitude for high-frequency sounds. Therefore, ILDs are primarily useful for localization of high frequencies.
3) Monaural spectral shape: Spectral shape cues arise from direction- and frequency-dependent reflection and diffraction of the pressure waveforms of sounds by the pinna that result in broadband spectral patterns, or shapes, that change with location
Interaural level differences (ILDs) are coded in the_______
lateral superior olive
The neurons comprising the medial superior olive (MSO) receive excitatory inputs from both ears via cells of the ______ on both sides
anteroventral cochlear nucleus (AVCN)
The primary auditory cortex (A1) (Broadmann’s area 41) is arranged in a tonotopic map with neurons responding to _____ located anteriorly and neurons responding to ______ more posterior.
lower frequencies,
higher frequencies
Sound possesses two primary qualities that are decoded by the auditory system: ___________
amplitude (or intensity) and frequency.
The ______ of a sound increases when the air is compressed more forcefully during the peak compression in each cycle, resulting in increased density of air. The perceptual correlate of intensity is called _______
intensity, loudness
The _____ is the number of times per second that a sound wave reaches the peak of rarefaction (or compression). This is measured in Hertz (Hz, cycles/sec). The perceptual correlate is ______
frequency, pitch
When the mechanical transmission of sound energy through the middle ear is degraded it results in ________
conductive hearing loss.
_______ hearing loss occurs from damage to or the loss of hair cells and or nerve fibers
Sensorineural
what are the 3 common cause of sensorineural loss
1) excessively loud sounds
2) exposure to ototoxic drugs (diuretics, aminoglygocide antibiotics, aspirin, cancer therapy drugs)
3) age (presbycusis).
what are common causes of conductive hearing loss?
1) filling of the middle ear with fluid during otitis media (i.e., ear infection)
2) otosclerosis, in which arthritic bone growth impedes the movement of the ossicles;
3) malformations of the ear canal (atresia), including “swimmer’s” and “cauliflower” ear;
4) perforation/rupture of the tympanic membrane;
5) interruption of the ossicular chain;
6) static pressure in middle ear.
Losses of 10-60 dB can occur in these cases.
A K+-rich fluid called _______ fills the scala media and bathes the stereocilia on the apical end of hair cells. In contrast, the basal end of the hair cell is bathed by __________, a fluid with ionic composition similar to blood (high Na, low K+) that fills the scala vestibuli and scala tympani.
Endolymph,
Perilymph
One can describe the sound response of single ANFs by a _________ where the number of action potentials fired per sec is plotted as a function of sound frequency. The peak of this function is the _____ of sound to which that fiber is maximally sensitive; higher and lower frequencies results in fewer action potentials per second.
frequency tuning curve,
“characteristic frequency”
Phase locking declines in neurons sensitive to frequencies greater than ______.
1.5 kHz
