chapter 6

Question 1

what is sound

Answer 1

changes in air pressure created by a vibrating object

Question 2

what is amplitude

Answer 2

intensity or loudness; measured by decibels

Question 3

what is frequency

Answer 3

pitch; measured in hertz

Question 4

what are the three main components of the hearing system and their functions

Answer 4

outer ear collects sound
middle ear amplifies/suppresses
inner ear transduces the soun

Question 5

what is the outer ear made of and their functions

Answer 5

pinna collects sound waves
ear canal carries the sound
tympanic membrane vibrates

Question 6

What is the middle ear made of?

Answer 6

Malleus, Incus, and Stapes. They connect the tympanic membrane to the oval window.

Question 7

What is the oval window?

Answer 7

The opening from the middle ear to the inner ear.

Question 8

Why do our ears need to amplify sound?

Answer 8

We live in a gaseous environment, but our ears have liquid in them. Sound travels worse when it needs to switch states of matter.

Question 9

What does the Malleus do?

Answer 9

Collects and focuses sound (it is large)

Question 10

What does the Incus do?

Answer 10

Connects the malleus with Stapes.

Question 11

What does the Stapes do?

Answer 11

The Stapes pushes on the oval window of the inner ear, generating vibrations in the inner ear.

Question 12

What muscles in the middle ear act to control volume?

Answer 12

Tensor tympani, which attaches to the malleus. Stapedius, which attaches to the stapes. These help to prevent damage and quiet your own sounds (e.g., eating).

Question 13

Where does auditory information get transduced?

Answer 13

The inner ear’s cochlea is the site of transduction.

Question 14

What does the cochlea contain?

Answer 14

The organ of corti, hair cells, auditory nerve fibers, and basilar membrane.

Question 15

How does the basilar membrane work?

Answer 15

It is filled with fluid and different parts vibrate at different frequency. (More detail) -> When the stereocila bends, tiplinks stretch and open K and Ca2+ ion channels allowing them into the cell. The depolarization opens voltage-gated Ca+ channels causing NT release that lead to action potentials in postsynaptic nerves.

Question 16

What are the two types of hair cells?

Answer 16

Inner and Outer Hair cells

Question 17

What characterizes Inner Hair Cells?

Answer 17

Round and small, about 3000-3500, they transduce sound, and are characterized by glutamate.

Question 18

What characterizes outer hair cells

T

Answer 18

They are long and slim, they amplify noise, there are 9000-12000 of them, and are characterized by acetylcholine.

Question 19

What are the afferent projections of IHCs

Answer 19

They send action potentials to the brain that provide sound perception (this is glutamate)

Question 20

What are the efferent projections of IHCs

Answer 20

Receive information from the brain the control responsiveness (this is ACh).

Question 21

What are the afferent projections of OHCs?

Answer 21

Send information about the basialr membrane to the brain.

Question 22

What are the efferetn projections from OHCs?

Answer 22

Receives input from the brain that modifies the stiffness of the basilar membrane, which leads to sharpening and amplifying sounds.

Question 23

What are the neural structure of sound?

Answer 23

Cochlear nuclei, superior olivary nucleus, inferior colliculi, medial genicular nucleus of the thalamus, A1.

Question 24

What does the cochlear nucleus of each ear do?

Answer 24

Receives sound input from the cochlea.

Question 25

What does the superior olivary nucleus do?

Answer 25

Receives info from both ears at one point (both cochlear nuclei).

Question 26

What does the inferior colliculi do?

Answer 26

Integrates signals, recognizes frequencies, and allows for pitch discrimination.

Question 27

What is the pathway from a sound to the secondary auditory cortex?

Answer 27

Sound > pinna > ear canal > tympanic membrane >Malleus > Incus > Stapes > oval window > cochlea > organ of corti > basilar membrane > hair cells > stereocila > tiplinks > calcium and potassium ions > voltage gated Ca channels open > vesicles bind to membrane through exocytosis > inner hair cells give sound sensation and outer hair cells give basilar membrane info > vestibulocochlear nerve > cochlear nuclei > superior olivary nucleus >inferior colliculus > medial geniculate nucleus > A1 > A2 | signal transmission begins at the cochlea

Question 28

what does the auditory cortex do

Answer 28

specialized for detection of biologically relevant sounds, like footsteps

Question 29

what is place coding

Answer 29

pitch determined by location of activated hair cells

Question 30

what is temporal coding

Answer 30

encoding the frequency of auditory stimuli in the firing rate of auditory neurons

Question 31

what is a tonotopic map

Answer 31

neurons for similar frequencies are located near each other

Question 32

what does the primary auditory cortex (A1) do

Answer 32

identify most basic elements of sound, pitch and amplitude

Question 33

what is intensity differences

Answer 33

differences in loudness at the two ears

Question 34

what is latency differences

Answer 34

differences between two ears in the time of arrival of sounds

Question 35

what is conduction deafness

Answer 35

disorders in the outer/middle ear prevent sounds from reaching the cochlea

Question 36

what is sensorineural deafness

Answer 36

hair cells fail to respond to movement of the basilar membrane (tinnitus)

Question 37

what is central deafness

Answer 37

damage to auditory brain areas, like stroke, tumors, or TBI

Question 38

what is amusia

Answer 38

loss of ability to perceive/produce melodic sounds/music; related to the inferior frontal gyrus and superior temporal gyrus

Question 39

what does the cochlear implant do

Answer 39

bypasses hair cells and electrically stimulates part of the cochlea

Question 40

how bad is hearing loss

Answer 40

might be a cause of dementia; brain compensation comes at the expense of other systems; linked to depression and risk of falls; linked to impaired memory

Question 41

what are the unique properties of smell

Answer 41

certain scents cause certain reactions; problems with smelling can reduce gray matter in the hippocampus; enrich environment; improved memory

Question 42

what are the strucutres for smell

Answer 42

olfactory epithelium - contains receptor cells olfactory bulb - contains glomeruli, receive input from olfactory cells olfactory nerve - axons running from epithelium to bulb mitral cells & tufted relay cells - make up the olfactory tract, carries information to brain

Question 43

what is the projection of the olfactory tract

Answer 43

olfactory cortex - smell amygdala - emotion olfactory tubercule - reward hippocampus - memory

Question 44

how do olfactory receptor cells differ

Answer 44

1. incredible diversity of olfactory receptor subtypes 2. die and are replaced in adulthood 3. bypasses the blood brain barrier

Question 45

what is the vomeronasal system

Answer 45

detects pheromones; receptors are found in vomeronasal organ, can detect sex hormones and signals genetic relatedness

Question 46

do humans communicate via pheromones?

Answer 46

humans do not have a VNO, but respond to odors of the opposite sex to alter the menstrual cycle or testosterone levels

Question 47

what is the TAARs theory

Answer 47

new class of olfactory receptor that respond to pheromones in rodents, located in the epithelium