Chapter 15

Question 1

cutaneous

Answer 1

anything related to skin

involved in somatosensory system

Question 2

3 parts of somatosensory system

Answer 2

cutaneous (perception of touch and pain)

proprioception (sense position of body and limbs)

kinesthesis (sense movement of body and limbs)

Question 3

skin (+ functions)

Answer 3

heaviest and largest organ

functions:
warns us of danger
protects us from bacteria or chemical agents
helps keep our organs and fluids inside body

Question 4

epidermis

Answer 4

outer layer of skin (visible to us)

made up of dead skin cells

Question 5

dermis

Answer 5

below the epidermis

contains mechanoreceptors

Question 6

mechanoreceptors

Answer 6

sensory receptors that respond to pressure, stretching, and vibration

Question 7

two ways neurons fire in the skin

Answer 7

slowly adapting receptors (SA - continuous firing from pressure)

rapidly adapting receptors (RA - firing only occurs at the beginning and end of a pressure, none in the middle)

Question 8

mechanoreceptors near the epidermis

Answer 8

merkel receptors (SA1, specific details of touch)

meissner corpuscles (RA1, handgrip control)

both contain small cutaneous receptive fields

(M&Ms are small)

Question 9

cutaneous receptive fields

Answer 9

area of skin that influences neural firing

Question 10

mechanoreceptors deeper in the dermis

Answer 10

ruffini cylinders (SA2, stretching of skin, like pinching)

pacinian corpuscles (RA2, vibration and fine texture through movement)

both contain large cutaneous receptive fields (can’t sense details)

(Power Rangers are large)

Question 11

corpuscles

Answer 11

onion-like structure

transmit electrical signals (neural firing) to nerve fibers (axons) when rapidly applied pressure (vibration) occurs but NOT when there is continuous pressure

Question 12

neural pathway from skin to brain

Answer 12

nerve fibers fire from peripheral nervous system (skin areas) to central nervous system (brain and spinal cord)

Question 13

2 major pathways into spinal cord

Answer 13

medial lemniscal pathway (large fibers, proprioceptive/position and touch info)

spinothalamic pathway (small fibers, temperature and pain info)

Question 14

where do neurons fire after going from the two major pathways into the spinal cord?

Answer 14

both pathways go from spinal cord to ventrolateral nucleus of thalamus

from thalamus to somatosensory cortices (both located in parietal lobe)

Question 15

somatosensory cortices

Answer 15

contains organized map of various parts of our body

somatosensory receiving area (S1)

secondary somatosensory cortex (S2)

both located in parietal lobe

Question 16

homunculus

Answer 16

latin for “little man”

another name to refer to body map

disproportionately represents body parts; magnification shows more use of body parts equating to perceiving more details in that body part

Question 17

experience dependent plasticity

Answer 17

our brains can change and adapt to experience and training for touch and other senses (ex. learning to play chords on guitar or read braille)

cortical representation of particular function becomes larger if that function is used often

representations of our brain areas are not totally fixed

Question 18

tactile acuity

Answer 18

our ability to detect details on the skin

high density or crowdedness of merkel receptors

high tactile acuity = larger areas in somatosensory cortex have smaller cutaneous receptive fields in the skin

Question 19

two different ways of perceiving tactile acuity

Answer 19

two point threshold (minimum separation needed between two points to perceive them as two points)

grating acuity (placing grooved stimulus on the skin and asking people to indicate the orientation/direction of the grating)

Question 20

surface texture

Answer 20

being able to sense our touch based on bumps and grooves of surface

Question 21

duplex theory of texture perception

Answer 21

we can perceive textures based on 2 cues:

spatial cues (detect texture based on size, shape, and distribution of surface element)

temporal cues (detect detailed texture based on the rate of vibration as skin is moved across the surface)

Question 22

active touch

Answer 22

person explores object by touching them

humans rely on this to interact with environment

Question 23

passive touch

Answer 23

object is applied to the skin (person is not doing the touching)

Question 24

haptic perception

Answer 24

our ability to perceive 3D objects by actively exploring the object with our hands and fingers

psychophysical research - we can identify objects accurately in 1-2 seconds

Question 25

three systems in haptic perception

Answer 25

sensory system (cutaneous sensations like touch, temperature, texture)

Question 26

social touch

Answer 26

interpersonal touch

focuses on effect of a person touching another person

Question 27

CT afferents

Answer 27

in the hairy part of skin, contain unmyelinated nerve fibers

can detect touch through slowly stroking the hair but causes the neurons to fire slowly

Question 28

social touch hypothesis

Answer 28

touch may be involved based on two functions:

discriminative function of touch (sensing details, texture, vibration, and objects from the skin/mechanoreceptors; activated in somatosensory cortex)

affective function of touch (sensing pleasure and positive emotions (CT afferents); associated with social touch; activated in insula based on slow stroking)

Question 29

pain

Answer 29

unpleasant sensory and emotional experience associated with actual or potential tissue damage

functions to warn us about dangerous situations (e.g., burning yourself)

Question 30

three types of pain

Answer 30

inflammatory (damage to tissues and joints or by tumor cells; ex. sunburn)

neuropathic (damage to central nervous system; ex. multiple sclerosis - body pain or weakness, dizziness, loss of vision)

nociceptive (caused by nociceptors signaling impending damage to the skin)

Question 31

nociceptors

Answer 31

specialized skin receptors that cause nociceptive pain

types of nociceptors respond to heat, chemicals, severe pressure, and cold

Question 32

direct pathway model of pain

Answer 32

early model in 1950s and 1960s suggesting that pain is caused when nociceptors are activated and sent to the brain

problems:
pain can be affected by mental state
pain can occur without stimulation of skin (phantom limb)
pain can be affected by attention

Question 33

three pathways for activating gate control system

Answer 33

nociceptors (neurons fire to open gate and transmission cells - pain increases)

mechanoreceptors (neurons from skin inhibits firing by closing gate and transmission cells - pain is inhibited)

central control (cognitive functions like attention, expectation, and distractions send neurons to fire from cortex to the gate control system to open or close gate)

Question 33

multimodal nature of pain

Answer 33

people describe pain based on two components/modes:

sensory (describing pain based on what they physically feel)

affective (describing pain based on emotional association)

Question 33

gate control model

Answer 33

there are different pathways by which pain is signaled to the spinal cord via a gate control system or circuit, which is sent to the brain

gates located in dorsal horn of spinal cord in which neurons fire and cause the gates to open or close (closed = less pain, open = more pain)

when gates open or close, the neural info is sent to transmission cells (neurons that send pain info to brain, like messengers)

Question 34

opiods

Answer 34

drugs used to reduce pain and increase euphoria

Question 34

four cognitive ways of influencing pain

Answer 34

expectation (surgical patients request less medication when they know what to expect; placebos can be effective)

shifting attention (virtual reality technology has been used to keep patients’ attention on other stimuli)

content of emotional distraction (participants could keep their hands in cold water longer when shown positive pictures)

hypnotic suggestion (fMRI study showed that hypnosis can produce pain and activate brain areas related to pain)

Question 35

how do brain chemicals affect pain perception

Answer 35

brain contains opiate receptors to process chemicals involved in pain

naloxone can be used to revive someone who overdoses (drug that blocks heroin from getting into opiate receptor sites in the brain; but can increase pain because it prevents release of endorphins)

Question 36

why do we have opiate receptors

Answer 36

our body produces natural painkillers (endorphins)

Question 37

endorphins

Answer 37

endogenous morphine

naturally occurring painkiller

Question 38

empathy

Answer 38

ability to share and vicariously experience someone else’s feeling

anterior cingulate cortex and anterior insula associated with empathy