auditory system 1

Question 1

monoaural localization

Answer 1

localization of sound with one ear that is dependent on sound from behind being muffled compared to sound from the front.

Question 2

ossicles in the middle ear

Answer 2

work to transfer air waves into mechanical movement, then convert mechanical movement into waves in the fluid filled inner ear.

Question 3

axons of the spiral ganglion

Answer 3

form the cochlear nerve and project to the cochlear nuclei of the upper medulla.

Question 4

oval window

Answer 4

where the foot of stapes contacts and creates a pressure wave that goes into the scala vestibuli

Question 5

pressure waves generated at oval windowq

Answer 5

vibrate the basilar membrane in the cochlear spiral, these are frequency components.

Question 6

organ of corti

Answer 6

transduces sound into action potentials in the spiral ganglion neurons

Question 7

basilar membrane of the cochlea

Answer 7

has resonance properties, shorter hair cells at base compared to apex, and narrower and stiffer near the base compared to the apex. this makes it so high frequency sound resonates at the base and low frequency sound resonates at the apex.

Question 8

organ of corti continued

Answer 8

lies in the cochlear duct, is a type of epithelium on the basilar membrane, continuous along the spiral of the cochlea, has 4 rows of hair cells, 3 outer 1 inner

Question 9

mechanoelectrical transduction

Answer 9

whereby vibration of the basilar membrane and subsequent shearing action of the tectorial membrane move steriocilia of hair cells which either cause depolarization or hyperpolarization.

Question 10

endolymph

Answer 10

in the cochclear duct (scala media) contacts the apical, steriocilia side of hair cells and is high in K+ low in Na+

Question 11

perilymph

Answer 11

high in sodium, low in K+ is in contact with the base of the hair cells and is in the scala tympani

Question 12

endolymph/perilymph potential

Answer 12

around +80 mV and is necessary for electrochemical driving force for depolarization of nerve terminals for transduction.

Question 13

inner hair cells

Answer 13

recieve 95% of afferent input from the spiral ganglion.

responsible for sound and frequency discrimination.

Question 14

outer hair cells

Answer 14

recieve 5% of spiral ganglion afferents and a majority of efferent olivochoclear fibers from the brainstem

Question 15

olivocochlear axons

Answer 15

asociated with auditory sharpening, the ability to focus on particular sounds and frequencies within a complex pattern of input.

Question 16

place theory

Answer 16

associated with the distribution of hair cells or tonotopic organization along the basilar membrane in the coclea, it is constant throughout. position of hair cell along the coclea is associated with the frequency it detects.

Question 17

characteristic frequency

Answer 17

corresponds to the frequency for a neuron where the threshold is the lowest.

Question 18

coding intensity in spiral ganglia

Answer 18

spiral ganglion cells respond differently to the onset of stimulus as apposed to maintained stimulus, higher response at onset with a plateu until cessation of stimulus.

Question 19

type 1 spiral ganglion cells

Answer 19

only innervate one or two inner hair cells, though one inner cell may be innervated by 20 or more type 1 cells
respond to narrow frequencies but have different thresholds of stimulation.

Question 20

type 2 spiral anglion cells

Answer 20

more sensitive to low intensity sounds than type 1, but less presicely tuned to a frequency
low intensity sound dtectors that are less specific.

Question 21

spiral gang cells

Answer 21

define volume and frequency characteristics of sound.