[Neuroscience] RE: Neur-sci Digest, Vol 57, Issue 5

Kamal J. AbuHassan via neur-sci%40net.bio.net (by kamal.abuhassan from hotmail.com)
Sat Feb 20 14:30:44 EST 2010



Hi Pathak=2C

Can you please see figure 1.6 of Izhikevich's book=2C "many biologists say =
that rebound responses are due to the activation and inactivation of certai=
n slow currents=2C which bring the membrane potential over the threshold or=
=2C equivalently=2C lower the threshold upon release from the hyperpolariza=
tion =96 a phenomenon called a low-threshold spike in thalamocortical neuro=
ns [Izhikevich]".

Best Regards=2C
Kamal.

> Date: Fri=2C 19 Feb 2010 12:06:23 -0500
> From: neur-sci-request from oat.bio.indiana.edu
> Subject: Neur-sci Digest=2C Vol 57=2C Issue 5
> To: neur-sci from magpie.bio.indiana.edu
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> Today's Topics:
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>    1. Thalamocortical Neurons (Kamal J. AbuHassan)
>    2. Re: Thalamocortical Neurons (Bill)
>    3. (no subject) (Dhruba Pathak)
>=20
>=20
> ----------------------------------------------------------------------
>=20
> Message: 1
> Date: Thu=2C 18 Feb 2010 18:46:53 +0000
> From: "Kamal J. AbuHassan" <kamal.abuhassan from hotmail.com>
> Subject: [Neuroscience] Thalamocortical Neurons
> To: <neur-sci from magpie.bio.indiana.edu>
> Message-ID: <SNT109-W464CE43F8DCD2618D46BC9FB470 from phx.gbl>
> Content-Type: text/plain=3B charset=3D"iso-8859-1"
>=20
>=20
> Hi=2C
>=20
> I have started to study Izhikevich's large scale model of mammalian thala=
mocortical systems=2C I have tried to simulate the neuronal model : v=3D(k*=
(v(i)-vr)*(v(i)-vt)-u(i)+I(i))/C and u=3Da*(b*(v(i)-vr)-u(i)) using the par=
ameters in fig. 10 of the appendix (for Thalamocortical Neurons: C=3D200=3B=
 vr=3D-60=3B vt=3D-50=3B k=3D1.6=3Ba=3D0.1=3B b=3D15 or zero depending on v=
=3B c=3D-60=3B d=3D10=3Bvpeak=3D40=3B) to get the burst firing pattern of T=
halamocortical Neurons (see fig.3A of the paper) but the model always gener=
ate the results for the tonic firing pattern=2C I am using the following ma=
tlab code from Izhikevich's book=2C chapter 8:
>=20
> C=3D200=3B vr=3D-60=3B vt=3D-50=3B k=3D1.6=3B % parameters used for (TC)=
=20
> a=3D0.1=3B b=3D15=3B c=3D-60=3B d=3D10=3B %=20
> vpeak=3D40=3B % spike cutoff
> T=3D1000=3B tau=3D1=3B % time span and step (ms)
> n=3Dround(T/tau)=3B % number of simulation steps
> v=3Dvr*ones(1=2Cn)=3B u=3D0*v=3B % initial values
> I=3D[zeros(1=2C0.1*n)=2C200*ones(1=2C0.9*n)]=3B% pulse of input DC curren=
t
> for i=3D1:n-1 % forward Euler method
> if v(i)>=3D-60
> b=3D0=3B
> end=3B
> v(i+1)=3Dv(i)+tau*(k*(v(i)-vr)*(v(i)-vt)-u(i)+I(i))/C=3B
> u(i+1)=3Du(i)+tau*a*(b*(v(i)-vr)-u(i))=3B
> if v(i+1)>=3Dvpeak % a spike is fired!
> v(i)=3Dvpeak=3B % padding the spike amplitude
> v(i+1)=3Dc=3B % membrane voltage reset
> u(i+1)=3Du(i+1)+d=3B % recovery variable update
> end=3B
> end=3B
> plot(tau*(1:n)=2C v)=3B % plot the result
>=20
>=20
> Can you help me please ?
>=20
> Thanks=2C
> Kamal.
>  		 	   		 =20
> _________________________________________________________________
> Hotmail: Trusted email with powerful SPAM protection.
> http://clk.atdmt.com/GBL/go/201469227/direct/01/
>=20
> ------------------------------
>=20
> Message: 2
> Date: Thu=2C 18 Feb 2010 20:28:59 -0800 (PST)
> From: Bill <connelly.bill from gmail.com>
> Subject: [Neuroscience] Re: Thalamocortical Neurons
> To: neur-sci from net.bio.net
> Message-ID:
> 	<f724181c-5086-4df3-93dd-f0d6653bd068 from e19g2000prn.googlegroups.com>
> Content-Type: text/plain=3B charset=3DISO-8859-1
>=20
> Hi Kamal=2C
>=20
> Hopefully someone else will be able to answer your question better
> than I... I don't know anything about matlab=2C but I can vaguely write
> stuff for NEURON. But I just had a couple of questions=2C any maybe when
> you answer them=2C you might see where you problem is.
>=20
> Firstly... am I right in reading that your time step is 1 ms? That
> hardly seems small enough? I would have thought you needed a time step
> of 10 micro seconds.
>=20
> Secondly=2C this must just be an integrate and fire neuron? I can't see
> any hodgkin-huxley type channels. Moreover=2C what is the mechanism for
> generating the "calcium current" needed for the burst firing? I can't
> see one.
>=20
> Finally=2C you must hyperpolarize a cell to get it to burst=2C are you
> sure you are hyperpolarizing it?
>=20
> On Feb 19=2C 7:46 am=2C "Kamal J. AbuHassan" <kamal.abuhas... from hotmail.com=
>
> wrote:
> > Hi=2C
> >
> > I have started to study Izhikevich's large scale model of mammalian tha=
lamocortical systems=2C I have tried to simulate the neuronal model : v=3D(=
k*(v(i)-vr)*(v(i)-vt)-u(i)+I(i))/C and u=3Da*(b*(v(i)-vr)-u(i)) using the p=
arameters in fig. 10 of the appendix (for Thalamocortical Neurons: C=3D200=
=3B vr=3D-60=3B vt=3D-50=3B k=3D1.6=3Ba=3D0.1=3B b=3D15 or zero depending o=
n v=3B c=3D-60=3B d=3D10=3Bvpeak=3D40=3B) to get the burst firing pattern o=
f Thalamocortical Neurons (see fig.3A of the paper) but the model always ge=
nerate the results for the tonic firing pattern=2C I am using the following=
 matlab code from Izhikevich's book=2C chapter 8:
> >
> > C=3D200=3B vr=3D-60=3B vt=3D-50=3B k=3D1.6=3B % parameters used for (TC=
)
> > a=3D0.1=3B b=3D15=3B c=3D-60=3B d=3D10=3B %
> > vpeak=3D40=3B % spike cutoff
> > T=3D1000=3B tau=3D1=3B % time span and step (ms)
> > n=3Dround(T/tau)=3B % number of simulation steps
> > v=3Dvr*ones(1=2Cn)=3B u=3D0*v=3B % initial values
> > I=3D[zeros(1=2C0.1*n)=2C200*ones(1=2C0.9*n)]=3B% pulse of input DC curr=
ent
> > for i=3D1:n-1 % forward Euler method
> > if v(i)>=3D-60
> > b=3D0=3B
> > end=3B
> > v(i+1)=3Dv(i)+tau*(k*(v(i)-vr)*(v(i)-vt)-u(i)+I(i))/C=3B
> > u(i+1)=3Du(i)+tau*a*(b*(v(i)-vr)-u(i))=3B
> > if v(i+1)>=3Dvpeak % a spike is fired!
> > v(i)=3Dvpeak=3B % padding the spike amplitude
> > v(i+1)=3Dc=3B % membrane voltage reset
> > u(i+1)=3Du(i+1)+d=3B % recovery variable update
> > end=3B
> > end=3B
> > plot(tau*(1:n)=2C v)=3B % plot the result
> >
> > Can you help me please ?
> >
> > Thanks=2C
> > Kamal.
> >
> > _________________________________________________________________
> > Hotmail: Trusted email with powerful SPAM protection.http://clk.atdmt.c=
om/GBL/go/201469227/direct/01/
>=20
>=20
>=20
> ------------------------------
>=20
> Message: 3
> Date: Fri=2C 19 Feb 2010 16:50:56 +0100
> From: Dhruba Pathak <pathakdhruba from gmail.com>
> Subject: [Neuroscience] (no subject)
> To: connelly.bill from gmail.com
> Cc: neur-sci from magpie.bio.indiana.edu
> Message-ID:
> 	<9fed4bc61002190750g52513b95ia6cb8b571c2af708 from mail.gmail.com>
> Content-Type: text/plain=3B charset=3DISO-8859-1
>=20
> Hi=2C
> I read some where comment that you have suggested for bursting.
>=20
> As I also do not know about the Mat lab program. To my knowledge=2C
> there are two types of neurons. One produce spontanous bursting while
> other needs stimulus. These stimulus may be depolarizing current or
> some blockers..
>=20
> However=2C I could not understand the correlation between
> hyperpolarization and bursitng. In fact the hyperpolarization will
> provide homeostatic environment to the cell.
>=20
> I also want to ask you=2C for example=2C is there any significance of
> studying the effect of some blocker in particular ion channel which is
> previously blocked by some other agents?
>=20
> Thanks in advance for your comments=2C
> Sincerely=2C
> Dhruba Pathak
>=20
>=20
>=20
> ------------------------------
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> Neur-sci mailing list
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> End of Neur-sci Digest=2C Vol 57=2C Issue 5
> ***************************************
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