Aging in auditory

Question 1

Conductive

Answer 1

tympanic membrane and ossicles. Conductive hearing loss is when sound is not reaching the inner ear at the appropriate level of amplification.

Question 2

Metabolic

Answer 2

endocochlear potential. Stria vascular dysfunction. Important for maintaining ionic composition so transduction can occur. Dependent on sodium-potassium pump. Aging causes less transduction because these cells die off.

Question 3

Sensory

Answer 3

Hair cells. Loss of hair cells results in decreased transduction. Fewer transducers and less amplification mean louder sound necessary to generate action potentials. Repeated loud noise exposure results in loss of hair cells.

Question 4

Neural

Answer 4

IHC synapse with spiral ganglion cells. Central pathways with excitatory and inhibitory balance. Overstimulation can lead to excitotoxicity. Auditory synapses and neurons fire at high frequencies.

Question 5

Hidden hearing loss

Answer 5

an imbalance of excitatory and inhibitory stimulation. Changes in cochlear output due to aging result in a mismatch of inputs in auditory centers. This can lead to the development of phantom sounds.

Question 6

Tinnitus

Answer 6

“ringing in the ears”. Central imbalance causing tonal perception.

Question 7

Mammalian color evolution

Answer 7

Mammal 4 opsin genes for cones (long wave, medium wave, short wave, ultra-short wave). Birds’ visual pigments seem to be constrained. Some optimization in fish, more diverse color vision. Mammals evolved from having 4 receptor types. Butterflies have 3-5 receptor types. Bes cover a large spectral range to discriminate different flowers. Fireflies have a twilight active signal, yellow cones increase contrast with leaves at dusk.