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Flashcards in Chapter 14 Deck (64):
1

3 parts of the somatosensory system

cutaneous senses

proprioception

kinesthesis

2

cutaneous senses

responsible for perceptions like touch and pain

usually caused by stimulation of the skin

3

proprioception

the ability to sense the position of the body and limbs

4

kinesthesis

the ability to sense the movement of the body and limbs

5

epidermis

outer layer of the skin

layer of dead cells

6

dermis

below the epidermis

7

mechanoreceptors

receptors that respond to mechanical stimulation like pressure, stretching, and vibration

8

Two categories of the mechanoreceptors

slowly adapting receptors - prolonged firing to continued pressure

rapidly adapting receptors - bursts of firing just at the onset and offset of pressure

9

two receptors close to the skin surface near the epideris

 

have small receptive fields

merkel receptor (SA1)

Meissner corpuscle (RA1)

10

cutaneous receptive field

area of skin that causes neurons to fire when stimulated

11

type of perception associated with:

Merkel receptor

Meissner corpuscle

fine details

 

controlling handgrip

12

Neuron firing patters of SA vs RA receptors

SA: continuously through pressure

 

RA: right at the beginning........right at the end

13

Two mechanoreceptors deeper in the skin

 

Large receptive fields

Ruffini cylinder (SA2)

 

Pacinian corpuscle (RA2 or PC)

14

Perception associated with:

 

ruffini cylindar

 

pacinian corpuscle

stretching of skin

 

rapid vibrations and fine texture

15

what is the travel issue involved with perception and skin receptors

receptors are distributed all over the body

signals must travel all the way to the brain before touch is perceived

16

dorsal root

bundles on each of the 31 segments of the spinal cord

conduct signals from the skin to the cord

17

two pathways of spinal cord touch signals

medial lemniscal pathway

spinothalamic pathway

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medial lemniscal pathway

large fibers carry signals relating to sensing the position of limbs and percieving touch

high speed

19

spinothalamic pathway

smaller fibers

carry signals relating to temperature and pain

 

20

where do the two spinal pathways lead

thalamus

most synapse in ventrolateral nucleus, some in other talamic nuclei

21

where do signals go after the thalamus

somatosensory receiving area (S1)                              in parietal lobe

possibly also to secondary somatosensory cortex (S2)

22

How is the somatosensory cortex organized

Into maps that correspond to locations on the body

23

homunculus

the body map in S1

 

24

example of touch magnification factor

areas like the fingers have larger areas in the brain dedicated to them (relative to their size)

25

neural plasticity monkey experiment

trained the monkies to use their finger in a certain way, eventually the area for that finger expanded in the cortex

26

Plasticity in musician

players of stringed instruments have larger cortical areas for the hand they use for the bow

27

tactile acuity

the ability to detect details on the skin

28

what determines the way we perceive details on the skin

receptor properties

29

where is there a high density of merkel receptors

 

why is this significant

fingertips

 

they are the part of the body most sensitive to detail

30

What is a physical feature that determines tactile acuity?

Spacing of receptors

 

(although they are the same on all fingers when some are better than others)

31

what is the cortical mechanism of tactile acuity

all based on receptive fields

areas better with detail have smaller fields that don't overlap

the ones that are worse have more overlapping fields - less seperation in cortex - less likely to feel something as two seperate points

32

surface texture

physical texture of a surface created by peaks and valleys

33

Katz on perception of texture

based on both spatial cues and temporal cues

34

spatial cues

provided by large surface elements (bumps and grooves)

can be felt when skin moves across and when it is just pressed down

35

temporal cues

info via vibrations caused by moving skin over a surface

fine texture

not detected unless fingers move

36

duplex theory of texture perception

the Katz idea that there are two types of receptors involved in texture perception

37

which receptor responds better to low frequencies and which one to high

low- Meissner corpuscle

high- Pacinian corpuscle

38

haptic perception

perception where 3d objects are explored with the fingers and hand

39

3 systems used during haptic perception

sensory system

motor system

cognitive system

40

passive vs active touch perceptions

passive - you feel the stimulation of the skin

active - you experience the object you are touching

41

exploratory procedures (EPs)

the movements of you hands and fingers while identifying 3d objects through touch

42

4 EPs

lateral motion

pressure

enclosure

contour following

43

what happens to neurons as you begin to move from mechanoreceptors towards the brain

they become more specialized

44

what kind of receptive fields do neurons in the ventral posterior nucleus (in the thalamus) have

center-surround

45

What are receptive fields like for touch in the cortex

some center-surround, some even more specialized (orientations, movement in certain direction, etc)

46

Specific touch neurons

specific orientations

movement in specific directions

grasping specific objects

 

 

47

while receptor stimulation will trigger a response, what other things can influence the size of response

attention

thinking

other perciever actions

48

3 types of pain

inflammatory

neuropathic

nociceptive

49

inflammatory pain

caused by damage to tissue or inflammation of joints or by tumor cells

50

neuropathic pain

caused by lesions or other damage to nervous system

51

nociceptive pain

caused by activation of nociceptors

52

nociceptors

receptors specialized to respond to tissue damage or potential damage

 

different kinds respond to different stimuli (heat, chemical, pressure, cold, etc)

53

early model of pain

direct pathway model

54

What are some reasons that contradict the direct pathway pain model

sometimes people dont percieve pain from serious wounds

 

phantom limb pain

55

gate control model of pain

Inhibitory messages sent to transmission cells from L-fibers (non-painful stim) and central control fibers (cognitive)

Excitatory messages sent to transmission cells from S-fibers (pain)

56

where are gate control cells

the dorsal horn of the spinal cord that extends from dorsal root

57

4 types of cognitive influences on pain

expectation

shifting attention

content of emotional distraction

hypnosis

58

pain matrix

all the areas of the brain that are involved in pain perception together

hypothalamus, amygdala, thalamus

S1, anterior cingulate cortex, prefrontal cortex, and insula

59

what is the multimodal nature of pain

it is sensory and emotional

60

What is the anterior cingulate cortex for in terms of percieving pain?

determining the affective component of unpleasantness

unpleasentness can change even when intensity remains the same

61

     a neurotransmitter that acts on the same receptors as opiods

endorphines (endogenous morphine)

62

naloxine

blocks opiods by attatching to receptor sites of heroin and endorphins

63

why does naloxone decrease the effectiveness of placebos

placebos cause the release of endorphins

64

where are placebo related endorphins released in the nervous system?

the specific locations patients expect pain to be reduced

 

brain activates the pathways to those regions