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Neuroscience Test 3 > Lecture 16 > Flashcards

Lecture 16 Flashcards

1
Q

Olfaction functions (3)

A

1) Warns of harmful substances in environment
2) Combines with taste for identifying flavor of foods
3) Mode of communication- pheremones

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2
Q

What can pheromones communicate? (4)

A

1) Reproductive behaviors
2) Territorial boundaries
3) Identification of individuals
4) Signal aggression or submission

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3
Q

What are the mechanisms and roles of human pheromones?

A

Still unclear

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4
Q

Odorants

A

activate transduction processes in neurons

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5
Q

Olfactory axons constitute…..

A

Olfactory nerve

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6
Q

Cribriform plate

A

thin sheet of bone through which small clusters of axons penetrate, coursing to the olfactory bulb

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7
Q

Anosmia

A

Inability to smell

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8
Q

Why are humans weaker “smellers” compared to many animals?

A

Smaller surface area of olfactory epithelium and density of olfactory sensors

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9
Q

What is the organ of smell?

A

Olfactory epithelium

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10
Q

Study form of olfactory epithelium

A

Got it!

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11
Q

Olfactory neuron (OSN) axons are unmyelinated and fragile- traumatic blows to head can sever axons and lead to….

A

anosmia

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12
Q

Olfactory neurons continually grow, die, and regenerate in a cycle that lasts about…..

A

4-8 weeks

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13
Q

Dogs have ____x more receptors/cm^2 than humans

A

100

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14
Q

How many transmembrane domain GCPRs does the olfactory receptor have?

A

7, each has a unique structure to allow for specific odorant binding

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15
Q

In most cases, OSNs can express how many olfactory receptor genes?

A

One (“one neuron- one receptor”)

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16
Q

Each GCPR is coupled to the olfactory specific _____ _____

A

G-Protein G(olf)

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17
Q

The large family of olfactory receptors suggests that around ________ odors can be recognized.

A

1 trillion

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18
Q

Transduction Mechanism of Vertebrate Olfactory Receptor cells (copy this down)

A

Odorants bind to olfactory GPCR–>
Stimulates the olfactory specific G-protein Golf –>
Activates adenylyl cyclase–>
Converts ATP to cAMP–>
cAMP binds to a cyclic nucleotide gated cation channel–>
Open cation channel allows influx of Na+ and Ca2+ which depolarizes the OSN and…–>
Ca2+ opens the Ca2+ -activated Cl- channels–>
Cl- efflux amplifies membrane depolarization

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19
Q

If the depolarizing receptor potential reaches threshold, OSN will…

A

fire action potentials and transmit information to the CNS

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20
Q

OSN axons synapse in the _____ ____ in olfactory bulbs

A

Spherical glomeruli

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21
Q

Incoming axons from the glomeruli synapse onto approximately ___ (___:___) second-order neurons

A

100 (250:1)

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22
Q

Subpopulations of olfactory receptor genes are expressed in non-overlapping regions of the….

A

Main olfactory epithelium (MOE)

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23
Q

Within each region the individual olfactory receptors are ______ dispersed

A

randomly

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24
Q

Activity within the olfactory bulbs can also be modulated by…..

A

Input from higher brain areas (eg. cotex, amygdala)

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25
Q

Within and between the olfactory bulbs, there is a very complex circuitry containing _______ and ______ connections.

A

inhibitory; exitatory

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26
Q

Axons of the olfactory tract branch and…..

A

Enter the forebrain

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27
Q

Direct projections from the olfactory bulb synapse in….

A

the olfactory cortex (a.k.a. piriform cortex)

28
Q

Potential mechanisms of odor identification: (3)

A

1) Population coding
2) Spatial coding (olfactory maps)
3) Temporal coding

29
Q

Population Coding

A

Distinct odors are determined by the activity of many OSNs in olfactory epithelium

30
Q

Broad Tuning of Single Olfactory Receptor Cells:
Each olfactory receptor protein binds to different _______ more or less readily, making the cell more or less sensitive to…..

A

Odorants; different odors

31
Q

Broad Tuning of Single Olfactory Receptor Cells:
Each odorant can also bind to….

A

many different olfactory receptors at different affinities

32
Q

Broad Tuning of Single Olfactory Receptor Cells:
Stronger odor concentrations also….

A

increase the OSNs response to the odorant.

33
Q

There is no evidence so far to support that the piriform cortex can “read and understand” the spatial map. Alternatively, this organization may simply be a more efficient way for the brain form connections between related neurons.

A

Debate on olfactory maps

34
Q

Olfactory maps:
Main olfactory bulb glomerular organization is ____ across individuals and these glomeruli receive input from ____ receptor type

A

Conserved; One

35
Q

Olfactory maps:
Specific odors result in…

A

different spatial patterns of activation in the MOB.

36
Q

Similar to the theory of _____ coding, it is difficult to show that the _____ coding is actually used to identify a stimulus.

A

Spatial; temporal

37
Q

Temporal coding in the olfactory system:
Temporal pattern of action potential firing changes….

A

when odors are presented to the animal

38
Q

Oscillatory activity when animals breathe in

A

Temporal coding in olfactory system

39
Q

Auditory system sensory systems (2)

A

1) sense of hearing: audition
2) sense of balance: vestibular system

40
Q

Vestibular system

A

Feels the tilts and rotations of the head, sense where our head and body are and how they are moving

41
Q

Cycle

A

distance between successive compressed patches of air

42
Q

Sound frequency

A

number of cycles per second expressed in hertz (Hz)

43
Q

What is sound?

A

Audible variations in air pressure, anything moves air molecules can generate a sound

44
Q

Audible sound range

A

20 Hz- 20,000 Hz

45
Q

Frequency

A

the number of sound waves per unit of time or distance.

46
Q

We perceive high-frequency waves as having….

A

a higher pitch/tone

47
Q

Intensity

A

the air pressure difference between peaks and troughs of the sound waves

48
Q

We perceive high-intensity waves as…

A

louder

49
Q

Pinna:

A

cartilage covered by skin, collect sounds

50
Q

Auditory canal:

A

ends at the tympanic membrane

51
Q

Ossicles:

A

transfer movements of the tympanic membrane to the oval window

52
Q

Cochlea:

A

fluid-filled, transforms physical motion of the oval window membrane into a neuronal response

53
Q

First stage of the auditory pathway

A

Sound wave moves the tympanic membrane →
Tympanic membrane moves the ossicles →
Ossicles move the membrane at the oval window →
Motion at the oval window moves fluid in the cochlea →    
Movement of fluid in the cochlea causes a response in sensory neurons.

54
Q

Rough outline of auditory pathway

A

Auditory receptors in cochlea–> Brain stem neurons–> MGN–> Auditory cortex

55
Q

Rough outline of visual pathway

A

Photoreceptors in eye–> Other retinal neurons–> LGN–> Visual cortex

56
Q

Components of middle ear (4)

A

Tympanic membrane
Three ossicles: malleus, incus, stapes
Footplate transmits sound vibrations to the fluids of the cochlea
Eustachian tube: connects nasal cavities

57
Q

Three ossicles:

A

malleus, incus, stapes

58
Q

Footplate:

A

transmits sound vibrations to the fluids of the cochlea

59
Q

Eustachian tube:

A

connects nasal cavities

60
Q

The fluid in the inner ear resists….

A

Being moved much more than air does

61
Q

Sound force amplification (2 ways

A

1) ossicles’ levering effect raise the force.
2) the surface area of the oval window is smaller than the area of the tympanic membrane.

62
Q

Pressure

A

force per surface area

63
Q

attenuation reflex:

A

Response when onset of loud sound.

64
Q

Tensor tympani and stapedius muscle contraction make the ossicle chain ___ ____ to diminish ______ _____.

A

rigid; sound conduction

65
Q

Functions of the attenuation reflex (3)

A

1) adapts the ear to continuous sound at high intensities and increases the dynamic range we can hear

2) Adapts ear to loud sounds, protects inner ear.

3) Suppresses low frequencies more, enables us to understand speech better.

Neuroscience Test 3 (7 decks)

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