Lecture 11: Smell and Hearing Flashcards
1
Q
olfaction
A
specialized for identifying special molecules called odorants
2
Q
what kind of receptors detects smell?
A
metabotropic g protein-coupled receptors
3
Q
how do receptors detect smell?
A
Metabotropic g protein-coupled receptors transduce ions into a change in membrane potential
4
Q
how many odorant receptors are there per odorant molecule?
A
1
5
Q
are odorant molecules lipid soluble?
A
yes
6
Q
are odorant molecules organic (made from life)?
A
yes
7
Q
Olfactory epithelium
A
the tissue of the nasal sinus that sits underneath the skull (the cribriform plate) and contains olfactory receptor cells
8
Q
how many types of receptor proteins does each olfactory cell express?
A
1
9
Q
Glomeruli
A
located in the olfactory bulb. Where olfactory receptor cells synapse, which in turn sends axons to the brain
10
Q
each glomerulus processes information about ____ types of olfactory receptor cells
A
1
11
Q
what process allows us to recognize smells?
A
combinational processing
12
Q
how many smells can humans recognize
A
tens of thousands
13
Q
how is smell perception developed?
A
through learned assocaitions
14
Q
is smell innate?
A
no
15
Q
where does olfactory information go?
A
to the primary olfactory cortex in the temporal lobe, then to the amygdala
16
Q
sound waves
A
fluctuations in air pressure that are caused by the molecules of air surrounding a vibrating object condensing and rarefying (pulling apart)
17
Q
how fast do sound waves travel?
A
~700 MPH
18
Q
what length of soundwaves can humans detect?
A
1.7 cm-17 m
19
Q
what sound wave frequencies can humans detect?
A
20-20,000 times per second
20
Q
3 dimensions of sound
A
loudness, pitch, and timbre
21
Q
loudness
A
corresponds to the amplitude or intensity of the molecular vibrations
22
Q
how is loudness determined?
A
by the total number of hair cells that are active and their overall activity levels
23
Q
pitch
A
corresponds to the frequency of the molecular vibrations
24
Q
how is pitch measured?
A
in hertz (Hz) or cycles per second
25
what is another word for pitch
tone
26
how is pitch determined?
place coding for moderate to high frequencies
rate coding for low frequencies
27
timbre
corresponds to the complexity of the sound
28
why do we use timbre
to determine the source of sound waves
29
how is timbre determined
Perceived by assessing the precise mixture of hair cells that are active throughout the entire cochlea
30
pinna
outer ear; receives sound from the external environment
31
typanic membrane
vibrates in response to sound waves and transfers them to the middle ear
32
middle ear
composed of three ossicles (small bones)
33
three ossicles
malleus, incus, stapes
34
oval windows
receives the vibrations from the ossicles and transmits them to the cochlea
35
cochlea
inner ear; a long, fluid-filled, coiled tube-like structure that contains sensory neurons. divided into three longitudinal divisions
36
three longitudinal divisions of the cochlea
Scala vestibuli
Scala media
Scala tympani
37
basilar membrane
encodes high notes on the end closest to the oval window. Like a xylophone, the low notes correspond to the longest (widest) section.
38
effect of sound waves on the basilar membrane
Sound waves cause the basilar membrane to move relative to the tectorial membrane, which causes hair cell cilia to stretch and bend`
39
organ of corti
Receptive organ that consists of the Basilar membrane on the bottom, the tectorial membrane on the top, and auditory hair cells in the middle
40
cilia
hair-like extension cells that transduce sound
41
outer hair cells
have cilia that are physically attached to the rigid tectorial membrane
42
inner hair cells
are not attached to anything. They sway back and forth with the movement of the solution
43
what does the movement of cilia do?
pulls open ion channels, which changes the membrane potential of hair cells.
44
there are ____ outer hair cells than inner hair cells
3 times
45
what type of hair cells transmit auditory information to the brain?
inner hair cells
46
people without _____ hair cells are deaf but people without _______ hair cells aren't
inner; outer
47
how do outer hair cells adjust the sensitivity of the tectorial membrane
they contract like muscles to adjust the sensitivity of the tectorial membrane to vibrations
48
how do outer hair cells affect inner hair cells
they influence the sensitivity of inner hair cells to specific frequencies of sound
49
tip links
elastic filaments that attach the tip of one cilium to the side of the adjacent cilium
50
intersertional plaque
the point of attachment of a tip link to a cilium
51
what kind of protein do interserional plaques contain?
Each intersertional plaque has a single ion channel in it that opens and closes according to the amount of stretch exerted by the tip link
52
how do hair cells release neurotransmitters
they don't have axons or action potentials so they continuously release neurotransmitters based on the amount of the stimulus
53
what is the effect of loud noises on the ear?
they can easily break tip links that interconnect each cilium. if broken, the tip links cannot transmit auditory information
54
can tip links grow back
yes, they grow back within a few hours and hearing comes back to normal
55
why does tip link breakage occur
as a protective measure against permanent damage
56
effect of glutamate on the ear
too much glutamate can release onto the cochlear nerve causing permanent cell death (excitotoxicity)
57
what percentage of 20 year olds have nose-induced hearing loss?
20%
58
place coding
The place where the cell is most active in the cochlea indicates the fundamental frequency (the pitch) of the sound wave
59
what types of frequencies are encoded by place coding?
moderate and high frequencies
60
rate coding
the rate of neurotransmitter release from the hair cells deepest in the cochlea determines the animal’s perception
61
what types of frequencies are encoded by rate coding?
very low frequencies
62
basilar membrane and place coding
Higher frequencies cause the bending of the basilar membrane, resulting in more hair cell activity in that area
63
tuning cures
indicate the sensitivity of individual inner hair cells, as is shown by their response threshold to pure tones of varying frequency. low points of the solid points indicate that the individual cells will respond to a faint sound only if it is a specific frequency. for louder sounds, cells will respond to frequencies above and below their preferred frequencies
64
Fundamental frequency:
the lowest frequency in a sound wave
65
overtone
sound wave frequencies that occur at integer multiples of the fundamental frequency
66
timbre
the specific mixture of frequencies (fundamental frequency + overtones) that different instruments emit when the same note is played
67
cochlear implant
- Typically 20-24 electrodes are positioned along the length of the cochlea
- By delivering electricity to distinct parts of the cochlea, we can cause actions potentials that correspond to different notes
- We can’t recreate this entire system, but we can create many different tones
68
fundamental frequency of human speech
85-180 Hz for men and 165-355 Hz for women
69
spatial location and phase differences and low-frequency sounds
innate method of detecting the source of continuous low-pitches sounds by means of phase differences
70
spatial location and loudness and high-frequency sounds
innate method of detecting the source of high-pitched sounds by analyzing the difference in loudness between ears
71
spatial location and timbre
- Sound waves bounce off the folds and ridges of the pinna before entering the ear canal
- Depending on the angle at which sound waves strike these folds and ridges, different frequencies of sounds can be enhanced or attenuated
72
sound pathway (steps)
1. The organ of Corti sends auditory information to the brain via the cochlear nerve.
2. These axons synapse in the cochlear nuclei of the medulla, where copies of the signal are made to be analyzed in parallel ascending paths.
3. Axons from the cochlear nuclei synapse in the superior olivary nuclei in the medulla and the inferior colliculi in the midbrain, both of which help localize the source of sounds.
4. Axons from the inferior colliculi synapse in the medial geniculate nucleus of the thalamus, which in turn relays the information to the primary auditory cortex in the temporal lobe
73
tonotropic represenation
The organization where different frequencies of sound are analyzed in different places of the auditory context
74
primary auditory cortex
the upper section of the temporal lobe, mostly hidden in the lateral fissure
75
auditory association cortex
the belt and parabelt regions
76
two streams of the auditory cortex
posterior and anterior pathways
77
posterior auditory pathway
where/ dorsal pathway
involved in spatial localization
meets up with the where vision pathway in the parietal lobe
78
anterior pathway
what/ ventral pathway
goes to the frontal lobe where the analysis of complex sounds occurs
79
auditory agnosia
various forms of auditory processing issues
80
amusia
The inability to perceive or produce melodic music
81
vestibular system
Detects gravity and angular acceleration of the head. maintains your upright head position, organizes your balance and corrects eye movements to compensate for head movements
82
Semicircular sacs
three ring-like, fluid-filled strictures that detect changes in head rotation (angular acceleration)
83
Cupula
gelatinous mass found in the ampulla of the semicircular canals; movies in response to the flow of fluid in canals
84
Vestibular sacs
a set of two receptor organs in each inner ear (utricle & saccule) that detect changes in the tilt of the head. Otoconia moves with gravity, depolarizing the hair cells it sits on
85
odorants
volatile substances that activate olfactory receptors
86
olfaction receptor cells
located in the olfactory epithelium
87
where do olfaction receptor cells synapse
in the glomeruli
88
how many types of receptors do olfaction receptor cells activate
1
89
loudness
the number of hair cells that are active
90
phase difference
Timing difference between the ears
91
level difference
Loudness difference between ears
92
how is the auditory cortex organized?
tonographically (by frequency)
