BIOELECTRO- MAGNETISM - Bioelectromagnetism · Generation of bioelectric signal V. m [mV] 200. 400....

16
BIOELECTRO BIOELECTRO - - MAGNETISM MAGNETISM Jaakko Malmivuo Demonstration slides

Transcript of BIOELECTRO- MAGNETISM - Bioelectromagnetism · Generation of bioelectric signal V. m [mV] 200. 400....

Page 1: BIOELECTRO- MAGNETISM - Bioelectromagnetism · Generation of bioelectric signal V. m [mV] 200. 400. 800. 1000-100-50. 0. 50. Time [ms] K + Na + K + K + K + K + K + K + K + K + K +

BIOELECTROBIOELECTRO-- MAGNETISMMAGNETISM

Jaakko Malmivuo

Demonstration slides

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AmberAmber

ηλεκτρον = amber

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Hans Christian Hans Christian ÖrstedÖrsted 18191819

Magnetic needle

I

I

Battery

B

B

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600

Generation of bioelectric signalGeneration of bioelectric signalVm [mV]

200 400 800 1000

-100

-50

0

50

Time [ms]

K+

Na+

K+

K+

K+

K+

K+

K+

K+

K+K+

K+

K+

K+

K+

K+ K+

K+

K+

K+

K+

K+

K+

Na+

Na+

Na+ Na+

Na+Na+

Na+

Na+

Na+

Na+ Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+K+

K+

K+

K+

K+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

K+

K+K+

K+K+

K+

K+

K+

K+

K+

K+

K+

K+

K+K+

K+K+

K+

K+

K+K+

K+K+

K+K+

Na+

Na+

Na+

Na+Na+

Na+

Na+Na+

Na+

Na+Na+

K+

Na+K+

K+

Restoring ionic balanceRestoring ionic balanceDepolarizationDepolarization RepolarizationRepolarizationNa+Na+

Na+

K+

K+

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Hubert MannHubert Mann

L E A D 3

L E A D 3L E A D 2

L E

A D

1

L E

A D

1

RR LL

FF

4

6

53

2

18

10

9

7

Monocardiogram1916

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Space clampSpace clamp

Ist = t1

x

Experimental chamberPhysiological salt solution

MembraneAxoplasm

Internal electrode

im

t = t4t = t2

t = t3

Vm is constant along the axon

Vm

A B

Φi

Φo

Vm rm

Em

cm

imimcimi

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mV

secImpulses in sensory axon

Reflex ArchReflex Arch

Muscle spindle

cm

secMuscle stretch

Stretch

MuscleSpinal cord

mV

secReceptor potential in sensory terminal

mV

secSynaptic potentials in motoneuron

mV

sec

Impulses in muscle fibers

mV

sec

Impulses in motoneuron

gm

sec

Tension in muscle

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TYPE OF DOUBLE LAYER SOURCESTYPE OF DOUBLE LAYER SOURCESEQUIVALENTEQUIVALENT SOURCESSOURCES

Double layerDouble layer sourcesource

Equivalent Equivalent double layerdouble layer sourcesource

Equivalent Equivalent dipoledipole

ClosedClosed double layerdouble layer

(Zero field)(Zero field)

(Null)(Null)

OpenOpen double layerdouble layer

Various double Various double layers withlayers with the same openingthe same opening

Open double Open double layer with twolayer with two openingsopenings

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0 5 10 15 25 30 35 40 45 50 55 60 6520 ms

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Heart rate 1/2Heart rate 1/2NORMAL SINUS RHYTHM Impulses originate at S-A node at normal rate

All complexes normal, evenly spaced. Rate 60 – 100/min.

S-A node

SINUS BRADYCARDIA Impulses originate at S-A node at slow rate

All complexes normal, evenly spaced. Rate < 60/min.

1.0 s

1 mV

2

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MOG

Biomagnetic signals

MEGMEG

MCGMMG

BiomagneticBiomagnetic signals and signals and magneticmagnetic noisenoise

Frequency [Hz]

Static field of earth

10-11

10-10

(pT) 10-12

(nT) 10-9

10-13

10-14

(fT) 10-15

10-16

10-8

10-7

10-4

10-3 10-2 10-1 100 101 102 103 104 105 106

Thermal noise field in eddy-current shield

Thermal noise field of bodyThermal noise fields

Laboratory noise

Line frequency and harmonic noise

Radio- frequency noise

high

low

Magnetic noise of brain

Geo- magnetic noise

Noise fields

Magnetic flux density [T]

Equivalent input noise

Commercial flux-gate magnetometer

NASA flux-gate magnetometer

SQUID magnetometer

Induction-coil magnetometer (at Tampere)

FMCG

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Lead fieldLead field detecting the magnetic dipole momentdetecting the magnetic dipole moment

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Jacques Fabien Gautier D’Agoty: “Anatomie des parties de la génértion de l’homme et de la femme”. Paris, 1773. Colored mezzotint. National Library of Medicine

Gautier D’Agoty’s colored mezzotints have a painterly quality. This pregnant woman calmly looks back at the viewer, a characteristic pose of 18th-century French portraiture.

The FetusThe Fetus

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Fetal ECG and MCGFetal ECG and MCGVernix Caseosa: A white, cheesy waxy substance that coats the skin of a fetus in late pregnancy.Fetus body, maternal abdomen: ρ

= 5 Ωm

Vernix Caseosa: ρ

= 0.5 MΩm

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Electromagnetic Method

ZE LMZMV J J σ∝ i

W.R. Purvis, R.C. Tozer, I.L. Freeston, 1990

The current IZE is fed through electrodes and the voltage VZM from the magnetic field detector is measured. The sensitivity is proportional to the dot product of the lead fields.

A

_ J ZE

_ J LM

B

_ J LE

_ J ZM

Feeding the current IZM to the coil and measuring the voltage VZE with the electrodes gives the same sensitivity distribution.

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Electro- retino- gram

Pigmentepithelium

RodCone

Horizontalcell

Bipolarcell

Amacrinecell

Ganglioncell

250

-250

00 10 20 30 40 50 60 70 80 90 100

R2

a2a1a-wave

Oscillating potentials

Early receptor potentials

V’ [μV]

Cone b-wave

Rod b-wave

c-wave

Time [ms]

Müler’s cellMüler’s cell

R1