《生物物理学》第5章神经生物物理学

生物物理学Biophysics第5章神经生物物理学——神经细胞的电生理现象及理论内容：神经元静息电位动作电位离子通道随机性诱发的自发动作电位的温度效应突起人脑是宇宙中已知的最复杂的结构，大约有1011个神经元，研究神经元及神经系统，是人类探索人脑奥秘的基础！树突髓鞘突触前终末胞体轴突细胞核神经元的结构神经元膜结构树突轴突突触细胞膜内、外离子浓度的分布去极化复极化恢复期静息期刺激加入阈值上的刺激第四节：离子通道随机性诱发的自发动作电位的温度效应OutlineStructure

of

Neuron

and

Action

potentialStochastic

Kinetic

of

ion

ChannelEffects

of

Temperature

on

Spontaneous

ActionPotentials

due

to

Channel

FluctuationsI.

Structure

of

Neuron

and

Action

potential·

Structure

of

Neuron树突轴突髓鞘突触前终末·

Basic

Neural

ProcessesSignal树突轴突突触前终末·

Neuron

Internal

Structure·

Structure

of

Cell

Membrane·

Ion

ChannelsThe

voltage-gated

channels

for

Na+

,

K+

,

and

Ca2+ionsall

share

the

same

basic

structural

themes.The

channel

is

essentially

arectangular

tube

whose

fourwalls

are

formed

from

either

four

subunits

(e.g.,

K+

channel),or

four

domains

of

a

singlepolypeptide

(e.g.,

Na+

channel).Each

subunit

or

domain

contains

six

transmembranealpha

helices,

labeled

S1-S6.Two

of

the

four

subunits

of

a

voltage-gated

ion

channel·

Relative

ion

concentrations

Across

the

Membrane·

Action

Potential

of

Neuron·

Hodgkin-Huxley

Equation

(1952)CdVmg

n4

(V

V

)m3gh(VV

)

gL

(VmLextV

)

I

(mKKmNamNadtn(1

n)ndtmn,

(1

m)mdt0.01(Vm

55)h(1

h)hhdtdhm,,0.125exp(

(V65)

/

80)1

exp[(V

55)

/1n0]0.1(Vm

40),0.108exp(

V

/18)1

exp[(V

40)/10m

]11

exp[

(V0.07exp[

(V65)

/20],35)

/10]nmmmmmhmhmdndmII.

Stochastic

Kinetic

of

ion

ChannelStochastic

Kinetic

of

K+

Channel:Stochastic

Kinetic

of

Na+

Channel:A:

View

of

the

foursubunits,

all

in

theresting

positionB:

One

subunit

in

theactive

positionC:

Two

subunitsin

theactive

positionD:

Three

subunits

inthe

active

positionE:

The

four

subunitsinthe

active

positionwhich

makes

the

channel

conductingK+

ChannelBNa+

ChannelA:

Closed

stateB:

Inactivated

stateC:

Open

stateCAIII.

Effects

of

Temperature

on

Spontaneous

ActionPotentials

due

to

Channel

FluctuationsααiBioSystems

81,

(2005)267-280i

:

The

opening

rateof

ion

channeli

:

The

closing

rateof

ion

channeliBioSystems

81,

(2005)267-280·

Spontaneous

potential

at

different

temperature6007008009001005000-800-20-40-6080604020T=

0

.

3

o

C6007008009001005000-800-20-40-6080604020T=

16

.

3

o

C600900100-80500080604020-20-40-60V

(mv)

0T=

26

.

3

o

C700

800time(ms)mThe

patch

size

is

fixed

at

Area=1

μm2600700800900100-805000806040200-20-40-60T=

31

.

3

o

C·

Mean

open

rate

of

channels

and

mean

duration

of

spike51015

20temperature(o

C)25300.000.010.021.00.030.050.060.070.08(a)Mean

Open

Rate

o0.f04C

hannelsNa+K+51015

20temperature(o

C)25300.00.51.52.0(

b)2.5Mean

Duration

of

Spikes(ms)area0.5area1.0area5.0Consistent

with

the

experimental

results

of

Correa

et

al.(1992),

and

that

of

Hodgkin

et

al.

(1952),

respectively.·

Mean

interspike

interval5

10

15202540302010706050Area=

0

.

055102510161412222018Area=

0

.

5510152020406080100Area=

5

.

0Mean

InterSpike

Interval

(ms)temperature

(o

C)25

5

101520010020030040050015

20Area=

20

.

00204060801000.0000.0050.0100.0150.020T=0.3o

C0204060801000.0000.0050.0100.0150.020T=10.3o

C020801000.0000.0050.0150.020T=20.3o

CISIH0.01040

60time

(ms)The

patch

size

is

fixed

at

Area=0.05

μm20204060801000.0000.0050.0100.0150.020T=28.3o

C·

Interspike

interval

histogram

(ISIH)0.0120.012020801000.0000.002ISIH0.0060.0040.0080.010T=12.3oC40

60time

(ms)The

patch

size

is

fixed

at

Area=20

μm20204060801000.010T=0.3oC0.010T=6.3oC0.0080.0080.0060.0060.0040.0040.0020.0020.0000.00000.0122040608010000.012204060801000.0000.0020.0040.0060.0080.010T=17.3oC·

Coherence

resonance

phenomenonCoherence

factor

is

defined

as

:HPis

the

half-width

of

the

peak[

Phys.

Rev.

Lett.

71,

(1993)807

]H

is

the

height

of

the

ISIH

peak

atP0510152025300.01.00.52.01.53.02.53.5Area=0.10510152025300.01.00.52.01.53.0

Area=0.52.53.50510

15

20temperature(oC)25300.50.01.51.02.52.03.53.0Area=20.0Area=5.036912150.50.00181.51.02.52.03.53.05100152temperature

(oC)250.0-0.5-1.00.51.0lg(Area)00

.

50001

.

0001

.

5002

.

0002

.

5003

.

0003

.

5004

.

000Characteristic

correlation

time:C

2

(

s

)ds0where

the

autocorrelation

C(t)

function

isC%x2

(t

)x%(t

)

x%(t),

x%(t

)

x

(t

)C

(

)x[

Phys.

Rev.