Post on 15-Apr-2018
BIOELECTROBIOELECTRO-- MAGNETISMMAGNETISM
Jaakko Malmivuo
Demonstration slides
AmberAmber
ηλεκτρον = amber
Hans Christian Hans Christian ÖrstedÖrsted 18191819
Magnetic needle
I
I
Battery
B
B
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+
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
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
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
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
0 5 10 15 25 30 35 40 45 50 55 60 6520 ms
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
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
Lead fieldLead field detecting the magnetic dipole momentdetecting the magnetic dipole moment
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
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
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.
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