cornell psych 205: day 07

8/14/2019 Cornell Psych 205: day 07

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Psychology 205

Perception

11 Feb 03

Day 07


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Primaries

Initial research on

touch sensitivies

pressure

pain (a lot of pressure)

Von Frey, the Von Frey hair,and adaptations of it

warmth & cold


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consistency,and

difference


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primaries & secondaries:

blends

hot - warm & cold !wet - pressure & coldoily - weak pressure & warmhard - cold & even pressuresoft - warm & uneven pressure

evidence: not bad

1. mixtures of secondaries from primaries2. physiological attunement (for pressure --> next)3. cultural salience (common language terms)


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Fingertip;glabrous


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1

2

3

4

glabrousskin

Mer

Mei

R

P


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hairyskin

Mer

Mei

Ruf

Pac


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from text

1

2

3

4


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from Day

06

1

2

3

4


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Two-point thresholds and their importance

indirect measure of lateral inhibition

direct indication of size of receptive fields


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compass and2-pt thresholds


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One of the basic

principles of

receptor organization

lateral inhibition

center-surroundorganization


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Braille resolution onfingertips


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site ofdecussation

Left hemisphere


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cortical mapsPut next to one anotherareas that need tocommunicate (rapidly)

Result:topologica

l maps

Left hemisphere


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Penfield


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sensoryhumuncul

i


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Insula, tastecortex


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The Pain Sense (algesia)

is it separate from other touch

qualities? YES

is it separable from touch? YES

is cutaneous pain related to

pain in other modalities?YES


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Pain and pain-related systems Systems:

1. hormonal - endorphins, enkephalins,morphine before (d) and after injury ()turning off pain -- analgesia

2. cognitive & cultural -

Shirley MacLean - deferring pain

couvade - turning on pain

3. neuronal - receptors and gate control theoryregistering pain, turning it on and off


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The Pain Sense (neuronal form) -- Von Frey Hairsreceptor: free nerve endings (cornea)

Pain Pressure Cold Warm

back of knee 230

chest 200 50 13 1

forearm 200 15 6 0.5

back of hand 190 14 7 0.5

ball of thumb 60 120

tip of nose 45 100 13 1

different distribution than pressure, warm, and cold sensitivities

cold & warm in equal proportion


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The Pain Sensereceptor: free nerve endings (cornea)

function - with the histamine release in damaged tissue

the tissue swells.

Swelling, pinching, and weight

compress free nerve endings and trigger pain


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differentpathwaythan touch

sharp pain

dull pain

pain decussation

in spinal cord

touch decussationin brain stem


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The Pain Sensehuge individual differences

first pass:the world of pain tolerance divides into two groups:

1. Those woman who have experienced

natural childbirth2. The rest of us


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Phantom limbs:body schema Henry Head (Stratton too)

arm losscortical take-over by facial area

and other areas

Phenomena:mislocation of phantomspain "in" lost limb - Mller

anomalous summation & delayscounterirritation

(stimulation-produced analgesia)


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mislocation


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cortical takeover immediatebut only partial

pain "in" lost limb - Mller

anomalous summation & delays

counterirritation(stimulation-produced analgesia)


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Gate Control Theory: 4 pathways, 3 fiber types

A 40 m/s (~90 mph) fast (L)A 20 m/s slow (S)C 3 m/s very slow


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3

4

2&4

1&3

cognitive/situationalsuppression of pain

1

2

3&4


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3. inhibits pain

4. increasespain

1. excites sharp

pain

2. excites dull pain

Likely responsible forphantom limb pain


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Counter-irritation:

rough rubbing increases activity in

pathway 3, which excites activity in SG,

which in turn inhibits pain (as antagonist

to pathway 4)


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Skin, Pain, & Phantom LimbsPrimaries -- pressure, pain von Frey hairs

temperature - warm & coldLateral inhibitiontwo-point thresholdsreceptive fields

center-surround organization -->role of inhibitionSkin & its innervation, cortical maps --> maps & organizationPain & its systems -- anecdotes -->multiple systems

1. hormonal - endorphins, enkephalins

morphine - before & after injury2. cognitive/culturalcouvade

3. neuronalGate Control Theory - Melzack -->role of inhibition

cornell psych 205: day 07

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