CBNS 124: Lecture Quiz Two

The endocochlear potential is produced as a result of: A. an 80 mV voltage potential difference between endolymph and perilymph B. the low levels of K+ inside hair cell C. biphasic receptor potential of the hair cells D. K+ channels on tips of hair cells

A

The hyperpolarizing phase of the biphasic receptor potential: A. is due to closing of MET channels B. results from adaptation C. is due to K+ current flowing out of the tips of hair cell D. is due to K+ current flowing out of the tips of hair cell

A. At rest, the channels are slightly open, allowing a tonic inwards K+ current into the hair cells which are then slightly depolarized at rest. Closing the MET channels, which occurs during deformation of the basilar membrane so that stereocilia bend away from the tallest one, then leads to hyperpolarization.

cochlear amplification: [Select All That Apply] A. is due to the outer hair cells B. occurs in connection with transduction C. occurs because electrical changes during transduction trigger mechanical changes in hair cell that changes resonance (displacement) of basilar membrane D. is an active process known as electromechanical transduction (EMT)

All of the Above. Electromotility of outer hair cells adds energy to oscillation caused by sound wave

The Place Code refers to: A. a method of encoding for sound intensity B. the orderly representation of sound frequencies preferred by an auditory structure C. tonotopy only in the basilar membrane D. location of the source of sound

B

What is the significance of MET channels? A. they refer to the tip link that connects all stereocilia on a hair cell B. they transduce mechanical deformation of basilar membrane into a receptor potential C. they are voltage gated Na+ channels D. they allow K+ (and Ca2+) to flow into the hair cell when stereocilia bend towards the shortest one

B

Glutamate release from hair cells is greater as a result of ___________.1 P A. Greater MET channel closing during transduction B. depolarization during transduction C. hyperpolarization during transduction D. tonic firing after transduction has triggered action potentials

B.

The tips of hair cells project into the scala media, containing endolymph, while the base borders the ___________ containing perilymph. A. scala media B. scala tympani C. scala vestibuli D. stria vascularis

B.

Characteristic frequency is a feature of the receptive field of: A. Inner hair cells B. Outer hair cells C. All auditory neurons in the auditory pathway D. Only neurons in A1 where isofrequency bands are located

C

A louder sound will produce which of the following? A. displacement of basilar m. that is larger at apex than at base where softer sounds are encoded B. activation of dorsal vs ventral cochlear auditory pathway C. interference with tonotopy only at levels above superior olivary n. D. activation of more auditory sensory neurons including spiral ganglion cells (spatial summation)

D.

Auditory neurons with binaural receptive fields are found in: A. basilar membrane B. basilar membrane superior olive C. A1 D. All but A and B are correct

D. Auditory neurons with binaural receptive fields are found at the level of the superior olive and downstream in the central auditory pathway (ventral cochlear pathway).

Phase-locking with volley can't occur at high sound frequencies (>4kHz): A. because of the intrinsic variability of neuronal action potentials B. because it is not required since high frequency sounds can't be heard by humans. C. and therefore tonotopy is used instead. D. because neurons either fire in response to every sound wave or not at all. E. A and C are correct.

E.

Temporal summation on the basilar membrane refers to more neurons firing when larger wider area on the basilar membrane is activated. T or F?

F: That's spatial summation not temporal.

The immense hearing fidelity of the auditory system is due, in part, to the relationship between hair cells and the spiral ganglion cells (SCGs) because A. each SGC gets auditory signals from more than one inner hair cell B. All SCGs receive auditory signals from many outer hair cells C. 95% of all SCGs receive auditory information from outer hair cells D. 5% of all SCGs receive auditory information from inner hair cells

None of the above. It is the 1:1 fidelity between Spiral Ganglion Cells and Inner Hair Cells that accounts for immense hearing fidelity.

Intensity coding of loud sounds (whether they are of low or high frequency) interfere with frequency coding at the basilar membrane. T or F?

T