Sensation And Perception Final Flashcards
(90 cards)
1
Q
Why is touch important?
A
- Survival: sensing danger (temperature), feedback from environment
- Social interactions: shaking hands, placing hands on back
2
Q
Somatic senses
A
- Sensing the physical state of the body based on a variety of info
- 5 of them
3
Q
Tactile sensation (somatic sense)
A
- Position and structure of objects making contact with body surface
4
Q
Nociception (somatic sense)
A
- Sensing noxious stimuli applied to body
2. Ex. Pain
5
Q
Temperature (somatic sense)
A
- Sensing stimuli that are warmer or colder than body surface
6
Q
Proprioception (somatic sense)
A
- The sense of the position of the limbs
7
Q
Kinesthesis (somatic sense)
A
- The sense of movement of the limbs and body
8
Q
Layers of the skin
A
- Epidermis: outer layer (including a layer of dead skin cells) hairy and glabrous (hairless)
- Dermis: inner layer of skin
- Skin considered a single (and largest) organ
9
Q
Mechanoreceptors
A
- Sensory receptors in the skin that respond to touch (pressure)
- Convert mechanical energy into electrochemical energy
- 4 kinds
10
Q
Merkle receptors
A
- fires to continuous pressure
- fine detail perception
- Location: epidermis
11
Q
Meissner corpuscle
A
- Location: epidermis
- On/off stimulation
- Tapping, grabbing perception
12
Q
Ruffin cylinder
A
- Fires to continuous pressure
- Stretching perception
- Location: dermis
13
Q
Pacinian corpuscle
A
- On/off stimulation
- Vibration perception
- Location: dermis
14
Q
Thermoreceptors
A
- Sensory receptors that respond to temperature
2. Warm fiber and cold fibers
15
Q
Warm fiber
A
- Increases its response rate as temp is increased
- Continues to fire as long as higher temp continues
- Decreases its firing rate when the temperature is decreased
- Does not respond to mechanical stimulation
16
Q
Cold fiber
A
- Increase firing rate when temp decreased
2. Continue to fire at low temperatures
17
Q
Cortical processing of touch
A
- Tactile information is represented in the primary somatosensory cortex (S1) and the secondary somatosensory cortex (S2)
- Location information is maintained in a spatial map
- S1 and S2 is in the parietal lobe
18
Q
Spatial map in S1
A
- Homunculus: Latin for little man
2. Larger = higher tactile acuity, greater cortical representation
19
Q
S1 neurons and receptive fields (somatosensory-style)
A
- Area on the skin that an S1 neuron is particularly sensitive to
- Firing rate increases when area is stimulated
- Center-surround organization
20
Q
How receptive fields map onto tactile acuity
A
- Tactile acuity: perceiving fine details via your sense of touch
- Large RF = low resolution, less detail
- Small RF = high resolution, more detail
- Merkel cells have smallest RF = can perceive most detail
21
Q
How RF size varies with location on skin
A
- Two-point threshold: the distance at which 2 pressure points can be distinguished
- Millimeters for fingers, centimeters for back because RF size is smaller on fingers than on back
22
Q
Cortical plasticity in S1
A
- S1 is plastic: changes with experience
- Training/ stimulation of fingers alters the cortical representation
- In humans: pianists have larger cortical area devoted to their fingers than normal individuals
23
Q
Perceiving objects via sense of touch
A
- Haptic exploration: exploring an object via your sense of touch
- Research shows that people can identify objects haptically in 1-2 seconds
24
Q
Physiology of tactile object perception
A
- Features of an object are processed first
- Occurs in S1 > S1 neurons are selective > respond to particular orientations/directions
- Features then combined to make a whole object
- Occurs in S2 and higher areas > some neurons selective to specific objects
25
S1 and attention
1. Some neurons in S1 only respond when monkey is attending to the tactile stimulus
26
Pain perception
1. Pain is necessary: need to know whether the body is hurt or in danger of being hurt
27
Experience of pain
1. Nociceptors: sensory receptors that respond to potentially harmful stimuli (temperature, pressure, chemical)
2. These receptors send pain info to brain stem and cortex
28
Types of physical pain
1. Nociceptive pain: nociceptor activation, results from extreme heat/cold, chemicals, extreme pressure
2. Inflammatory pain: damage to tissues, joints
3. Neuropathic pain: carpal tunnel, damage to nervous system from spinal cord injury or stroke, phantom limb pain
29
Brain areas involved in pain perception
1. Pain is multimodal
2. Somatosensory cortex S1 (parietal lobe)
3. Thalamus
4. Temporal lobe
5. Amygdala
6. Hypothalamus
7. Prefrontal cortex
8. Anterior cingulate cortex
30
Gate control theory of pain (modulating pain)
1. Spinal cord contains neurological gate that blocks pain signals or allows them to continue to the cortex
2. Factors that open/ close the gate: nociceptor activity, activity in other receptors, input from the brain
31
Emotional factors that open/close gate (gate control theory)
1. Open gate: anxiety, worry, panic, depression
2. Close gate: happiness, relaxation, excitement,
3. endorphins close gate: massage, nutrition, injections, exercise, positive attitude, pacing activities, distractions from pain
32
Cognitive factors in modulating pain: anticipation
1. Anticipation
2. Pain tolerance study;
- subjects had to put hand in ice water, FMRI measured
3. Results: anticipating pain produced same brain activation as experiencing the pain
33
Cognitive factors in modulating pain: expectations
1. Expectation
| 2. If patient told a procedure won't hurt, they will experience less pain (placebo effect)
34
Cognitive factors modulating pain: attention
1. Attention
2. Experience of pain might not set in until you attend to the injury
3. Attending away from the injury: can withstand pain longer
- ex. Show men pictures of attractive females, they can keep their hand in ice water for longer
35
Hypnosis
1. Hypnosis induced pain is similar to physical pain
| 2. Hypnosis can also reduce pain perception
36
Emotional and social pain
1. Emotional (break ups)
2. Social (exclusion from a group)
3. Empathic pain (watching someone else hurt, actually activates pain network)
37
Phantom limb pain
1. Experiencing pain/ sensation in a limb that is no longer there
2. Why? Cortical representation of limb is still there
3. Treated with mirror therapy
38
Inability to perceive pain
1. Congenital (from birth) inability to perceive pain
| 2. Extremely dangerous condition
39
Olfaction
1. Our sense of smell
40
Functions of olfaction: identifying substances
1. Smell helps to identify substances
2. Knowing if smell is delicious or deadly
3. Detecting fire/smoke in house
4. Baby needing diaper change
5. Knowing if it's time to shower
41
Functions of olfaction: identify sexual partners
1. Smell helps to identify sexual partners
2. We all have unique, genetically determined scent
3. Study: males slept in t-shirt for 2 nights (no deodorant).
- Females sniffed t-shirt and rated smell for pleasantness and sexiness
4. Before study: males and females tissue typed for major histocompatibility complexes (vital part of immune system)
5. Results: females gave highest ratings to t-shirts worn by men whose MHCs differed most from their own
42
Functions of olfaction: filter and humidity
1. Smell helps to filter and humidify air
2. Air is warmed
3. Hairs in nasal cavity remove dust/debris
43
Smell stimulus (2)
1. Odor: smell
| 2. Odorant: what produces the smell
44
At what point can we detect smell in environment?
1. Olfactory receptors activated by 1 molecule odorant
2. But smell isn't perceived until many molecules processed
3. Most smells consist of many molecules (coffee = 100 molecules)
45
Odor detection thresholds
1. Detection threshold: lowest concentration at which an odorant can be detected (measured in parts per billion ppb)
2. Different threshold for different odors
- some easy/ not easy to smell (skunk vs. ants)
3. Detection thresholds vary by person
46
Odor sensitivity is affected by?
1. Odor sensitivity affected by: time of day, age, sex, time of month for females (> when ovulating), smoking
2. Some people put off by odors others cannot even smell
47
Odor sensitivity in animals
1. Rats 8-50 times more sensitive to odors
2. Dogs: 300-10,000 more sensitive
3. Receptors for these animals equally sensitive
4. Difference is number of receptors: humans have 10 million, dogs have 1 billion
48
Recognizing odors
1. Threshold for odor recognition not the same as threshold for odor detection
2. We can only identify a small subset of the smells we experience
3. Might be a memory problem rather than a sensory problem
49
Primary odors
1. Musky: perfumes, aftershave
2. Putrid: rotten eggs
3. Pungent: vinegar
4. Camphoraceous: moth balls
5. Ethereal: dry cleaning fluid
6. Florals: roses
7. Peppermint: mint gum
50
Smelling process
1. Odorant molecules reach olfactory mucosa, containing olfactory receptor neurons (ORNs)
2. Odorant molecules bind to receptor proteins on the cilia of the ORNs
3. Binding opens ion channels, depolarizing the cell
4. Signal is sent to the olfactory bulb in the brain
5. Glomeruli organize information in the olfactory bulb
6. Organized signal is sent to primary olfactory cortex (piriform cortex) and then to secondary olfactory cortex (orbitofrontal cortex) where higher-level processing occurs
51
Olfactory mucosa
1. dime-sized region on the roof of the nasal cavity
52
Olfactory receptor neurons (ORNs)
1. Located on the mucosa, respond to odor stimuli and transduce signal
2. Humans have 10 million ORNs of 350 different types
53
Neurogenisis
1. ORNs replaced every 5-7 weeks
2. New neurons must: 1. Grow axons that travel from mucosa to olfactory bulb (3-4cm)
3. Duplicate connections made by predecessor cells
54
Receptor proteins on ORNs
1. We have 1000 receptor proteins, each sensitive to different odorants
55
Olfactory bulb
1. Brain structure where olfactory signals are collected from the
ORNs
56
Glomeruli
1. Groups of cells in olfactory bulb that receive input from similar ORNs
2. Receive input from 5,000-10,000 ORNs
3. Help organize and categorize by smell
4. Has a odotopic map
57
Important odor notes (3)
1. Odor information goes directly to the brain (no intervening synapses)
2. Odor information is organized in the brain (like visual, auditory, and touch)
3. We have many more types of receptors for smell than for our other senses, yet we rely on it the least.
58
Organization of smell
1. Odors occur concurrently (simultaneously)
| 2. Perceptual system separates them
59
Top down influences on odor perception
1. Past experience: quickly identify a familiar smell
2. Expectations: general understanding for how things smell
3. Knowledge/descriptive info: smell reported more pleasant when told it was cheddar cheese than when told it was body odor
- pleasantness ratings associated w/higher orbitofrontal activation
60
Anosmia
1. Odor blindness
2. Causes: congenital, blockage/inflammation of nasal pathway, damaged olfactory receptors, damaged olfactory nerve, damaged piriform cortex, old age, smoking/snorting things, drugs
3. Can be in only 1 nostril (if damage is unilateral)
4. Can be specific to certain smells (sweet, musky, etc.)
61
Consequences of losing sense of smell
1. Eating is less pleasant
2. Loss of appetite and weight
3. Dull sex drive
62
Phantosmia
1. Hallucinations of smell
2. Often unpleasant
3. Can be caused by migraines, Parkinson's, mood disorders, damage to piriform cortex, schizophrenia
63
Why is taste important?
1. Security system: sensing when something is poisonous
2. Homeostasis: getting nutrients, cravings tell us what we need
3. Pleasure purposes: eating feels good
64
Taste
1. ability to respond to soluble substances (things that dissolve on our tongue
65
Tastant (5 of them, what are they?)
1. Taste stimulus (various categories)
2. Sour: potentially spoiled
3. Sweet: nutritional value
4. Bitter: potentially toxic
5. Salty: regulating bodily fluids
6. Umami: savory/meaty flavored
66
Tongue
1. Receptor surface for taste
67
Papillae
1. Bumps on the tongue
68
Filliform
1. Cone-shaped
2. Located along entire tongue
3. Does not contain taste buds
69
Fungiform
1. Mushroom shaped
2. Located along tips and sides
3. Contains taste buds
70
Foliate
1. Folds, located on sides
| 2. Contain taste buds
71
Circumvallate
1. Mound shaped
2. Located at back
3. Contains taste buds
72
Taste buds
1. Has 10,000 taste buds
2. Located on papillae
3. Clustered on edges and back of tongue (not many in the middle)
4. Short life span...only 10 days
5. Each taste contains 50-100 taste receptor cells
6. Micovilli protrude into the taste pore
7. This is where tastant info is received
73
Taste cells
1. One taste cell contains various receptor sites for the different flavors
2. At receptor sites is where transduction begins
74
Taste transduction
1. Salty: Na+ influx
2. Sour: reduction of K+ outflow
3. Sweet: elicits signal via enzyme cascade
4. Bitter: blocks signal via enzyme cascade
75
Taste Transduction simplified
1. Mouth
2. Tongue
3. Papillae
4. Taste buds
5. Taste cells
6. Receptor sites
76
Neural code of taste
1. All taste cells contain receptor sites for all 4 tastes
2. But certain taste cells might respond more to one type than another
3. Seems like taste receptors have a preference
77
3 pathways to brain through cranial nerves (CN)
1. Glossopharangeal nerve: back of the tongue
2. Chords tympani nerve: front/sides of tongue
3. Vagus nerve: mouth and larynx, can taste without tongue
78
Taste process in the brain
1. CNs synapse in the nucleus of the solitary tract in brain stem
2. Thalamus
3. Primary taste cortex: insula, frontal operculum
4. Secondary taste cortex: orbitofrontal cortex
79
Insula
1. Folded deep in the brain
2. Signals disgustingness or unpleasantness
3. Primary taste cortex
80
Frontal operculum
1. Cortical region that folds over the insula
| 2. Primary taste cortex
81
Secondary taste cortex
1. Orbitofrontal cortex
82
Interaction between taste and smell
1. Smell and taste are processed in same secondary area of the cortex
2. Orbitofrontal cortex: gathers info from all the senses
3. Contains bimodal neurons: neurons that respond to 2 senses
- smell and taste
- audition and vision
83
Flavor perception in orbitofrontal cortex
1. Flavor = smell and taste components activated in OFC via bimodal neurons
2. Either smell or taste will activate this area, and in turn will activate the other
3.
84
Hunger and OFC
1. Study in monkeys
2. When monkey hungry: increased firing rate and licking rate of cream intake
3. As monkey satiated: decrease firing rate and licking rate
85
Bottom up and top down process of taste
1. Physical properties of food: smell, temperature, texture, consistency
2. Color
3. Genetics: genetic aversions to food (cilantro)
4. Prenatal nutrition: mom ate spicy food when pregnant, you probably like it
5. Physiological: salt content in saliva, cravings
6. State of olfaction: whether or not you can smell
7. Experience: food you ate as a child, conditioned taste aversion (food sickness)
8. Expectation: we know what it taste like
9. Anticipation: salivation occurring before you taste
10. Emotional state: sad, happy, depressed, anxious
11. Adaptation: as you eat, you adapt to flavor, may make you bored
86
Supertasters
1. More sensitive to flavors (mostly bitterness)
2. More taste buds than non tasters
3. Picky eaters
4. Super tasters 25% pop
5. Medium tasters 50% pop
6. Non tasters 25% pop
87
Threshold for taste
1. Extremely difficult to measure
2. Super tasters and non-tasters have different threshold ceilings
3. No threshold of the Texan is the same for everyone
88
Disorders of taste: Ageusia
1. inability to taste
2. Very uncommon
3. All 3 pathways impaired
4. Causes: radiation therapy, head trauma, congenital
89
Disorders of taste: Dysgeusia
1. Tasting without stimulation, distorted taste
2. Results in experiencing taste as salty, metallic or bitter
3. Causes: drugs, damage to taste nerves
90
Disorders of taste: Hypogeusia
1. Decreased taste
2. Result in decreased food intake, weight loss
3. Causes: aging, impaired olfaction (a cold)
