ar 2008b eda bfbk physiol

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Stress Management and Biofeedback Stress Management and Biofeedback

WorkshopWorkshop

ElectroElectro--dermal Activity (EDA) Physiologydermal Activity (EDA) Physiology

By: Dr. Ernesto Sh. Korenman, July/By: Dr. Ernesto Sh. Korenman, July/20082008Dr. Ernesto Sh. Korenman, 2008

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Sweat Gland Physiology Sweat Gland Physiology

Dr. Ernesto Sh. Korenman, 2008

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SkinSkin

Outermost Layer: EpidermisOutermost Layer: Epidermis

Middle Layer: DermisMiddle Layer: Dermis

Deepest Layer: HypodermisDeepest Layer: Hypodermis

Neural innervationsNeural innervations

Blood VesselsBlood Vessels

Sweat GlandSweat Gland


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Sweat Sweat GlandsGlands•• Glands secrete Glands secrete 99 99 % water with % water with

dissolved salts, traces of ammonia, dissolved salts, traces of ammonia, and other metabolic byand other metabolic by--products.products.

•• Can collectively produce up to Can collectively produce up to 77--8 8 liters a day.liters a day.

•• Humans contain about Humans contain about 22..5 5 million million sweat glands in our body.sweat glands in our body.


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•• One type of sweat gland occurs in the palms, One type of sweat gland occurs in the palms, soles, forehead, and armpitssoles, forehead, and armpits

›› Control body temperatureControl body temperature

›› Function in cold sweats = responses made Function in cold sweats = responses made when you are frightened, nervous or when you are frightened, nervous or embarrassedembarrassed

•• Other sweat glands occur on other body Other sweat glands occur on other body surfacessurfaces

Sweat Glands: typesSweat Glands: types


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Control of Eccrine Sweat GlandsControl of Eccrine Sweat Glands

•• Activation is controlled directly by the Activation is controlled directly by the Sympathetic Division of the Autonomic Nervous Sympathetic Division of the Autonomic Nervous System System

•• Paradoxically receive primarily sympathetic Paradoxically receive primarily sympathetic cholinergic fibers (Acetylcholine releasing)cholinergic fibers (Acetylcholine releasing)

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Skin Conductance and sweatSkin Conductance and sweat

•• Skin conductance Skin conductance begins to change begins to change before moisture before moisture level level

•• As duct fills with As duct fills with sweat, skin sweat, skin conductance conductance increasesincreases

Sweat glandSweat gland


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Emotional SweatingEmotional Sweating


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SweatSweat--emotion link: the Limbic System emotion link: the Limbic System

•• Limbic System activates the sweating pathway controlled by Limbic System activates the sweating pathway controlled by

the Hypothalamus.the Hypothalamus.

•• Affected by, and responds to, emotional stimulus, such as Affected by, and responds to, emotional stimulus, such as

emotionally charged questionsemotionally charged questions

ThalamusThalamus CortexCortex

MedullaMedullaCerebellumCerebellum

HyppocampusHyppocampus

AmygdalaAmygdala

HypothalamusHypothalamus


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Sweat Gland response to stressing soundSweat Gland response to stressing sound

Threatening SoundThreatening Sound

ThalamusThalamus

Auditory CortexAuditory Cortex

Limbic SystemLimbic System

HypothalamusHypothalamus

Sweat Gland responseSweat Gland response


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Electrodermal Activity (EDA) Electrodermal Activity (EDA) RecordingRecording


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EDA electrodesEDA electrodes

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What is skin conductance?What is skin conductance?

•• Resistance RResistance R==V/ I (Ohms)V/ I (Ohms)

•• Conductance C Conductance C == 11/ R / R (mho or Siemens)(mho or Siemens)Voltage (V)Voltage (V)

Current (I)Current (I)

BatteryBattery


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Sweat gland and skin conductanceSweat gland and skin conductance


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Sweat and EDASweat and EDA

•• Phasic skin conduction response (greater conductance) occurs due to filling Phasic skin conduction response (greater conductance) occurs due to filling of the sweat ducts in the epidermis and the constant expulsion of fluids from of the sweat ducts in the epidermis and the constant expulsion of fluids from the sweat poresthe sweat pores

•• Recovery to tonic levels of skin conductance is attributed to deposition of Recovery to tonic levels of skin conductance is attributed to deposition of

moisture on the skin or remoisture on the skin or re--absorption of fluids by the sweat glandsabsorption of fluids by the sweat glands

•• Amount of sweat delivered to the ducts and number of sweat glands that Amount of sweat delivered to the ducts and number of sweat glands that are activated influence the amplitude of the conductance response are activated influence the amplitude of the conductance response

•• Glands on the palmar and plantar surface have been recognized as Glands on the palmar and plantar surface have been recognized as responding to emotional stimuli, with the remainder responding to thermal responding to emotional stimuli, with the remainder responding to thermal

changeschanges


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Skin conductance/resistance unitsSkin conductance/resistance units


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Skin conductance responseSkin conductance response

•• Skin becomes a better Skin becomes a better conductor of electricity conductor of electricity when external stimuli when external stimuli are presented are presented

Stimulus


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Quantification of EDA response (EDR)Quantification of EDA response (EDR)

-- LatencyLatency

-- AmplitudeAmplitude

--RecoveryRecovery

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SCL graphSCL graph

Cumulated Cumulated stimulistimuli

Recovery Recovery after stimuliafter stimuli

RelaxingRelaxing


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Types of real SCL graphTypes of real SCL graph

SteadySteady LabileLabile


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Specific (Sp) vs. nonSpecific (Sp) vs. non--specific responsespecific response

Stimulus Stimulus

TW=Time WindowTW=Time Window

SpecificSpecific SpecificSpecific

Non Non SpecificSpecific

Non Non SpecificSpecific


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Respiration artifact detectionRespiration artifact detection

InhaleInhale InhaleInhale

SpecificSpecificNon Non SpecificSpecific


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SCR to fearful musicSCR to fearful music


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Skin

Conduct

ance

Skin

Conduct

ance

Res

ponse

(R

esponse

(µµ

S)

S)

0

1.5

3 Run2

0

1.5

3

10 50 90 130

Time (sec)

Run3

0

1.5

3 Run1

=Tone=Tone

Habituation of SCR to toneHabituation of SCR to tone

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The EndThe End

ar 2008b eda bfbk physiol

Health & Medicine