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Flashcards in 6A Sensing the Environment Deck (129):
1

Visual Cues

depth, form, motion, constancy

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Binocular Cues

Vision involving two eyes that give humans the ability to receive visual cues from the enviornment

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What are two components of binocular vision?

Retinal Disparity Convergence

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Retinal Disparity

The fact that eyes are 2.5 inches apart allowing humans to get slightly different views of objects --> provides depth

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Convergence

Provide humans depth through using eye muscles - Far objects cause the eye muscles to relax -Close objects cause the eye muscles to contract

6

Monocular Cues

Visuals cues that use one eye that provide the form of an object

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What are examples of monocular cues?

Relative Size Interposition (overlapping) Relative Height - things higher away are further Shading/Contour Motion parallax - Things further away appear slower

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Constancy

Our perception of object doesn’t change even if it looks different on retina

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What is sensory adaptation?

Our senses are adaptable and they can change their sensitivity to stimuli

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List the 5 Types of Sensory Adaptation

Hearing Touch Smell Proprioception Sight

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Hearing Adaptation

Muscles in the inner ear contract at higher noises

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Touch Adaptation

Temperature receptors become desensitized over time

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Smell Adaptation

Desensitized receptors in your nose to molecule sensory information over time

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Proprioception

the sense of the position of the body in space

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Proprioception Adaptation

Mice raised upside down would accommodate over time, and flip it over

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Sight Adaptation

Eyes can adapt to various degrees of light via up and down regulation - light adaptation: pupils constrict down-regulate cones and rods - dark adaptation: pupils dilate to up-regulate cones and rods

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Just Noticeable Difference (JND)

The threshold at which you’re able to notice a change in any sensation i.e. can notice the change in weight from 2 lb to 2.2 lb but not if you go up to 2.05 lb

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Weber's Law

JND for a stimulus is proportional to the magnitude of stimulus

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Weber's Law Equation

Delta I/I = k Intensity Change(or JND)/Intensity=Constant

20

What describes the relationship between incremental threshold and background intensity?

Linear relationship

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Absolute Threshold of Sensation

The minimum intensity of stimulus needed to detect a particular stimulus 50% of the time

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Why is absolute threshold of sensation important?

It is more accurate than determining the absolute level something can be sensed when taking into account variations within or across individuals

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Absolute Threshold of Sensation vs Just Noticeable Difference

ATS is when you can notice a stimulus while JND is when you can notice a change in the intensity of a stimulus

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What influences the absolute threshold of sensation?

Different psychological states - Expectations - Experience (how familiar you are with it) - Motivation - Alertness

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Subliminal stimuli

Stimuli below the absolute threshold

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The vestibular system

System that involves the inner ear and limbs to help with the sense of balance and spacial orientation

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Which structure within the inner ear is involved in balance?

Semicircular canals - posterior, lateral, and anterior

28

Endolymph

Fills the canal that allows us to detect what direction our head is moving in, and the strength of rotation

29

Otolithic organs

Helps us to detect linear acceleration and head positioning. In these are Ca crystals attached to hair cells in viscous gel.

30

Vestibular System and Dizziness

Endolymph doesn’t stop spinning the same time as we do, so it continues moving and indicates to brain we’re still moving even when we’ve stopped – results in feeling of dizziness

31

Signal Detection Theory

Looks at how we make decision under conditions of uncertainty – discerning between important stimuli and unimportant “noise”

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How do we determine signals?

Hit - Signal present and recognize Miss - Signal present and don't recognize it False Alarm - Signal isn't present but recognize it Correct Rejection - Signal isn't present and recognize it isn't there

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Signal Strength

d' = strength hit > miss (strong signal) miss

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Strategy of Determining Strength

c; how do you determine if signal is present

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Two types of signal strategy

conservative (always say no unless 100% sure signal is present. Bad thing is might get some misses). Or liberal (always say yes, even if get false alarms)

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Signals have two distributions

- Noise distribution - Signal distribution

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How is signal strength determined?

d' is the difference between noise distribution and signal distribution

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What are the shifts in the signal distribution graphs?

So if signal shifted to right, d’ would be big and easy to detect. If left, d’ very small and more difficult to detect.

39

List the various strategies

- The strategy C can be expressed via choice of threshold – what threshold individual deems as necessary for them to say Y vs. N. Ex. B, D, C, beta, just dif variables. - If we were to use B, let’s say choose this threshold – 2. So anything greater than 2 will say Y to, anything less say N. So probability of hit is shaded yellow, and false alarm is pink. - D = d’-B, so let’s say d’ in this example is 1, so 2-1=1. So if we use D strategy, anything above 1 = Y. - C strategy is an ideal observer. Minimizes miss and false alarm. C = B – d’/2. So in our example, it’s 2- ½ = 1.5. So anthing above a 1.5 When C = 0, participant is ideal observer. If <1, liberal. If >1, conservative. - Beta, set value of threshold = to the ratio of height of signal distribution to height of noise distribution. ln beta = d’ x C = 1 x 1.5 = 1.5

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Bottom-Up Processing

stimulus influences our perception

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Top-Down Processing

Background knowledge influences perception --> i.e. where's waldo

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Gestalt Principles

Idea that humans can group images/objects in an organized fashion 

Gestalt (shape, form) 

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List of Gestalt Principles

Similarity – items similar to one another grouped together Pragnanz – reality is often organized reduced to simplest form possible (Ex. Olympic rings) Proximity – objects that are close are grouped together Continuity – lines are seen as following the smoothest path Closure – objects grouped together are seen as a whole

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45

Conjunctiva 

 

The first layer where light hits 

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Cornea

transparent thick sheet of tissue, anterior 1/6th

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Anterior chamber

space filled with aqueous humour, which provides pressure to maintain shape of eyeball.

48

Pupil

hole made by iris, which determines eye color

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Lens

bends the light so it goes to back of eyeball

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Posterior chamber

area behind the ciliary muscle, also filled with aqueous humor.

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Vitreous chamber

filled with vitreous humour, jelly-like substance to provide pressure to eyeball

52

Retina

Region of the eye filled with photoreceptors.

  • Macula – special part of retina rich in cones.
  • Fovea – completely covered in cones, no rods. → Helps with finding fine details and pictures (Helps you see where waldo is)

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Choroid

pigmented black in humans, a network of blood vessels. Bc all of the light to the eye is reflected off of it

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Sclera

whites of the eye, thick fibrous tissue that covers posterior 5/6th of eyeball. Attachment point for muscles.

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Ciliary body

Suspensory ligaments attached to a ciliary muscle

secrets the aqueous humor

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Sensation 

A neural impulse that created from a neural impulse 

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Photoreceptor

Helps convert light into a neural impulse in the eye

59

What is light? 

What is the EM spectrum?

A electromangentic wave that is part of the EM spectrum 

Spectrum that contain everything from gamma rays to AM/FM waves --> visible light is in the middle

 

60

What is the visible light spectrum?

Part of the EM spectrum that ranges from 400 nm to 700 nm 

Violet to Red

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Path of light into the eye

Light enters pupil and goes to retina, which contains rods and cones

 

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Rods 

There are 120 million rods, for night vision

  • Light comes in, goes through pupil, and hits rod. Normally rod is turned on, but when light hits turns off.
  • When rod is off, it turns on a bipolar cell, which turns on a retinal ganglion cell, which goes into the optic nerve and enters the brain.

63

Phototransduction cascade 

Way for the brain to recognize that light is entering the eyeball. Involves initially turning off the rods in the retina so other molecules can turn on

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Rhodospin 

A multimeric protein with 7 discs that contains retinal 

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retinal

a small molecule that changes conformation from bent to straight when it is hit by light

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Phototransduction Cascade Process 

  1. Light hits the retinal causing it to change shape so rhodopsin also changes shape.
  2. This begins a cascade of events with transducin 
  3. Transducin breaks from rhodopsin, and alpha part comes to disk and binds to phosphodiesterase (PDE).
  4. PDE takes cGMP and converts it to regular GMP.  Na+ channels allow Na+ ions to come in, but for this channel to open, need cGMP bound. As cGMP decreases, Na channels closes.
  5. As less Na+ enters the cell, rods hyperpolarize and turn off. Glutamate is no longer released, and no longer inhibits ON bipolar cells (it’s excitatory to OFF bipolar cells). 
  6. Bipolar cells turn on. This activates retinal ganglion cell which sends signal to optic nerve to brain.

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retinal ganglion cell

Cell that sends signal induced by light to optic nerve 

68

What is inside a rod? 

optic discs, large membrane bound structures – thousands of them. In membrane of each optic disc are proteins that fire APs to the brain.

69

Similarities and Differences between Cones and Rods 

Similarities - Have the same structure and both trigger phototransduction cascade 

Differences - 

  • Rods have rhodopsin while cones have photopsin 
  • More rods than cones in the eye 
  • Rods are more sensative to light 
  • Cones detect color 
  • Rods have a slower recovery time than cones 
  • Rods are in the periphery in the eyeball while cones are in the fovea 

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Blind Spot 

Where optic nerve connects to retina where no photoreceptors are present 

71

One of the contributing factors to the eye having such a high resolution?

There are no axons in the fovea so little is obstructing light from hitting the cones directly --> this is not the case for rods in the periphery 

72

Use a graph to describe photoreceptor distribution 

Q image thumb

X axis = Location within the eye 

Y axis = Density of particular receptor 

Rods are highest in the periphery and lowest in the Fovea 

Cones are highest in the fovea and lowest in the periphery  

 

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73

Describe Visual Processing 

  1. All light from the left visual field goes to the left side of the brain, all light on the right visual field goes to the right side of the brain
  2. The light that hits the nasal side of the eye cross at the optic chiasm to go to the opposite side of the eye 

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Feature Detection 

When looking at an object, you need to break it down into its component features to make sense of what you are looking at

Look at 3 components - color, form motion 

76

Trichromatic theory of color 

Color vision comes in 3 forms - red, green, and blue - due to the 3 types of cones 

RED (60%), GREEN (30%), BLUE (10%).

 

 

77

How does the eye processes color? 

object reflects red --> red light hits red cone in eye --> fire axon potential --> 

brain is like OH RED!! ),

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Parvocellular Pathway 

Method of the eye to detect form 

Very good with spacial resolution but poor temporal resolution 

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Magnocellular Pathway 

Method of detecting motion 

High temporal resolution and poor spatial resolution --> no color present 

80

Parallel Processing 

The ability to utilize all 3 forms of feature detection at the same time

Simulatnious processing of incoming stimuli taht differs in quality 

81

What are the two major compontents of hearing? 

  1. Pressurized sound wave 
  2. Hair cell 

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Sound Waves 

Areas of high and low pressure that form when air molecules are pressurized and try to escape 

83

Frequency of Sound Waves 

How close the peaks of the sound waves are 

84

How are humans able to listen to different frequencies at the same time?

Ear has to breaks up the various frequencies. Able to do that because sound waves travel different lengths along cochlea.

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Pinna

outer part of ear where sound waves first hit

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external auditory meatus

auditory canal, next place where sound wave travels after hitting the pinna

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Another name for Eardrum 

tympanic membrane, place where sound wave travels after hiting exernal auditory meatus (auditory canal) 

88

Process of Hearing 

  1. Sound wave first hits the pinna 
  2. Then it goes to external auditory meatus (aka auditory canal)
  3. Then hit the tympanic membrane (Eardrum)
  4. As pressurized wave hits eardrum, it vibrates back and forth, causes these 3 bones to vibrate – malleus, incus, and stapes. (MIS - 3 smallest bones in the body 
  5. Stapes is attached to oval window (aka elliptical window).
  6. As the oval window gets pushed gets pushed, the fluid pushes fluid and causes the fluid to go around cochlea
  7. At tip of cochea, the fluid can only go back, but goes to the round window and pushes it out.
  • Reason fluid doesn’t go back to oval window, is because in middle of cochlea is a membrane – the organ of Corti 
  • Keeps happening until energy of sound wave is dissipated. Meanwhile hair cells in cochlea are being pushed back and forth and send info to auditory nerve.

89

Classicification of ear 

Where is the outer ear?

What makes up the middle ear?

What makes up the inner ear? 

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Outer Ear - Pinna to Tympanic Membrane 

Middle Ear - Malleus to Stapes 

Inner Ear - Cochlea and semilcircular canals 

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90

What determines the rate at which the stapes moves?

The stimulus which causes the sound wave

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Organ of Corti

Membrane in the cochlea tha splits it into two 

In both the lower and upper membrane of the organ of corti, there are hair cells that help the fluid move back and forth 

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92

Hair Bundle in the Organ of Corti

Little filament that make up the hairs in the 

93

What structure in the ear is used to differentiate 2 different sounds?

Cochlea

94

Frequencies and Hearing

Humans can hear between between 20-20000Hz

Low frequency example is a base drum 

High frequency example is that of a bee 

95

Basilar tuning

there are varying hair cells in cochlea. Hair cells at base of cochlea are activated by high frequency sounds, and those at apex by low frequency sounds. --> long waves travel further

- Once the sound hits its designated hair cell, the hair cell is activated and an AP is sent to the brain

 

-AP reaches the primary auditory cortex in the temporal lobe --> hear time ticking, temperol lobe 

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96

Tonotypical Mapping 

Tones are mapped close together in the brain based upon their frequency 

97

What are Cochlear Implants? 

A surgical procedure that attempts to restore some degree of hearing to individuals with sensory narrow hearing loss

98

Sensory Narrow Hearing Loss

`nerve deafness`

problem with conduction of sound waves from cochlea to brain

99

How do Cochlear Implants Work?

  • Receiver goes to a stimulator which reaches the cochlea. Receiver receives info from a transmitter. Transmitter gets electrical info from the speech processor. Speech processor gets info from microphone.
  • Sound -> microphone -> transmitter (outside the skull) sends info to the receiver (inside). Then it sends info to the stimulator, into the cochlea, and cochlea converts electrical impulse into neural impulse that goes to brain.

100

What are the parameters for somatosensation? 

Types of Sensation

Intensity of Sensation

 Timing of Sensation

 Location of Sensation

101

List the types of Sensation

(TP3)

Temperature (thermoception)

pressure (mechanoception)

pain (nociception)

position (proprioception)

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Timing of Somatosenation 

  • Non-adapting- neuron consistency fires at a constant rate
  • Slow-adapting - neuron fires in beginning of stimulus and calms down after awhile
  • Fast-adapting - neuron fires as soon as stimulus start...then stops firing. Starts again when stimulus stops).

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Sensory Adaptation

change over time of receptor to a constant stimulus – typically downregulation

Ex. As you push down with hand, receptors experience constant pressure. But after few seconds receptors no longer fire.

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Importance of Sensory Adaptation 

if cell is overexcited cell can die. Ex. If too much pain signal in pain receptor (capsaicin), cell can die.

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Sensory Amplification

sensory receptor is upregulated 

Ex. Light hits photoreceptor in eye and can cause cell to fire. When cell fires AP, can be connected to 2 cells which also fire AP, and so on.

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Somatosensory Homunculus

Map of the body in the brain, specifically in the cortex

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Where in the cortex is the homunculus?

The sensory strip of the cortex - specific areas in the strip are receiving information from specific parts of the body

108

How is tthe sensory strip useful for neurosurgery?

Used to make sure that the surgeon isn't removing a part of the brain that deals with sensation to a particular part of the body 

109

Propioception 

Sense of balence/position in the body 

Deals mostly with cognition 

This is dictated by muscle spindles, which are sensative to stretch to alert the body how contracted muscles are

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Kinaesthesia 

Deals with the movement of the body 

Behavioral component of bodily movement - i.e. teaching yourself how to move successifuly to complete a task

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Nociception 

Ability to sense Pain 
 

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thermoception

Ability to sense temperature

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TrypV1 receptor

receptors that sense temperature and are sensative to pain

sends a signal to the brain via confirmational change when it senses heat 

114

What are the 3 types of nerve fibers?

A-beta fibres - Fast ones are thick and covered in myelin (less resistance, high conductance)

A-gamma fibres -– smaller diameter, less myelin.

C fibres - small diameter, unmyelinated (lingering sense of pain).

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Capsaicin

Molecule that can bind to TrypV1 receptor to trigger pain

Sometimes used for arthritis medication

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Taste and smell 

When you eat, molecules travel up back of throat and some go into back of your nose. So you’re using your sense of smell in conjunction with taste.

If your smell is knocked out, you can’t taste things as well.

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olfactory epithelium

specialized epithelial tissue inside the nasal cavity that is involved in smell

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Cribriform plate

Separates the olfactory epithelium from the brain

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Olfactory Bulb

A bundle of nerves that sends little projections through cribriform plate into the olfactory epithelium 

There are receptors at the olfactory epithelium that is connected to the bulb for a particular molecule

120

How does a molecule bind to a receptor and cause an AP?

The molecule binds to the
GPCR receptor on odor molecule --> GPCR on olfactory epithelia --> G-protein dissociates
and causes a cascade of events inside the cell --> G protein binds to ion channel which
allows cells outside the cell to come inside--> opens and triggers an AP --> goes to
cribriform plate --> glomerulus --> activate mitral/tufted cell --> synapse to brain.

121

Glomerulus

Location in the olifactory bulb where all of the AP from a specific molecule's receptors feed into 

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Mitral/Tufted Cell 

Cells within at the glomerulus where the receptors synapse to to project the smell to the brain.

123

Pheromones

Molecules released by animals that serves as special olfactory cues 

124

What parts of the olfaction system are involved in pheramon processing

Specialized part of olfactory epithelium in animals – the accessory olfactory epithelium. It sends projections to the accessory olfactory bulb.

  • Within the accessory olfactory epithelium, you have the vomeronasal system.
  • In vomeronasal system, there are basal cells and apical cells. They have receptors at tips.
  • Triangle will come in and activate receptor on basal cell here. Basal cell sends axon through accessory olfactory bulb to glomerulus, which eventually goes to the amygdala.

125

5 Tastes on Tongue 

bitter, salty, sweet, sour, and umami (ability to taste glutamate)

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Taste Buds

Cells concentrated anteriorly on the tongue. Taste buds can be fungiform (anterior), foliate (side), and circumvallate (back)

  • A taste bud has all 5 of the receptors used to detect taste

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Labelled lines model

Each receptor has an axon, which all remain separate to the brain. And they all synapse on dif parts of the gustatory cortex

example - Glucose hits tongue, activates sweet cell (because it has sweet sensitive receptors), triggers cascade of events so cell depolarizes, and travels down axon to the brain

128

What type of receptors do each of the 5 tastes have?

Sweet, umami, and bitter cells GPCR receptors

Sour and salty rely on ion channels

129

What happens if we put salty receptor inside a sweet cell?

Receptors in membrane bind to glucose. But let’s insert a salty receptor. Since axon from cell leads to brain, if NaCl comes in, it activates the receptor, + ions go inside, sweet cell depolarizes and fires AP, and brain interprets it as a sweet signal.