[Eeglablist] Meaning of ITC

[Makoto Miyakoshi]

--- P$B>-%%(Bl Gunnar Larsson <Pal.Gunnar.Larsson at epilepsy.no> wrote:

> From:P$B%;%e<+(Bl Gunnar Larsson<Pal.Gunnar.Larsson at epilepsy.no>
> To:'Makoto Miyakoshi' <mataothefifth at yahoo.co.jp>
> Date:Wed, 15 Apr 2009 08:11:58 +0200
> Subject:RE: [Eeglablist] Meaning of ITC
> 
> Dear Makoto
> 
> > Dear Pal,
> > 
> > Thank you for the reply. It is very informative and interesting...
> > almost exciting.
> > 
> > It seems to me, however, that the term 'synchronization' is used in
> > different meanings between you and me. Maybe you mean it in a sense
> of
> > 'synchronized firing among neurons at a given moment', right? There
> are
> > actually papers that report inter-channel coherency, and that is
> > certainly a kind of synchronization. But the concept of ITC is
> 'inter-
> > trial'
> > synchrony: it compares EEG phases AMONG TRIALS and measure phase
> > variance, so it had nothing to do with inter-channel phase
> synchrony.
> 
> You do have a point. I don't know your research at all. Is inter
> trial between stimuli or between sessions or between persons? I have
> not thought this through, but I was thinking between stimuli and
> something not unlike to bereitschaft-potentials, but mainly my pont
> was on the relation betwen bold and EEG.
> 
> > 
> > Maybe we'd better create a term 'Inter-neuronal coherency (INC)' in
> > contrast with inter-trial coherency (ITC).
> Coherency in EEG was very popular, but it did not lead to very much
> more than some papers. One of hte main reasons was that spatial
> filters were not applied (except by Gevins) and hence there were too
> much blurring of the findings. I guess you should look at Alan Gevins
> works from around 1984. He did 128 channel EEG and made arrows
> showing coherences and latencies between brain areas. His
> illustrations have been widely used in the literature. To my
> knowledge he did not look at ITC.
> > 
> > I'm analyzing my EEG data and found some experimental effect in
> ITC,
> > but I have no idea how to interpret it... because theoretically it
> is
> > not related to neither ERSP (EEG power) nor BOLD.
> Back to bereitschaft - there is no expectance in this?
> > 
> > I will ask EEGLABlist technicians how to post our communications to
> the
> > list. By the way, so far you are the only person who replied. My
> > gratitude is all yours (haha).
> > 
> 
> Regards
> 
> P$B%;%e<+(Bl
> 
> > Makoto
> > 
> > 
> > 
> > --- P$B<@</<'<'(Bl Gunnar Larsson <Pal.Gunnar.Larsson at epilepsy.no> wrote:
> > 
> > > Dear Makoto
> > >
> > > First - I thought it went back to the list, but did not check to
> see
> > > that it did.
> > >
> > > My points was mostly towards the Nunez take on this;
> synchronization
> > > does not require energy. Hence synchrony comes out with high EEG-
> > power
> > > and no BOLD-effect. On the other hand, interneurons in cortex are
> so
> > > symmetrical that they do not show up on EEG, but consumes quite a
> bit
> > > of energy and will be well seen in fMRI.
> > >
> > > According to the above, your phase locking(?) would be expected
> to
> > > influence EEG-power but not BOLD (or ?).
> > >
> > > Another point from Nunez: If you have a million stochastic firing
> > > neurons, they would give a resultant amplitude of A*sqrt(n) where
> A
> > is
> > > the amplitude and n is number of neurons. However, when they are
> > > synchronized, the amplitude is n*A. So a million neurons will
> show
> > > same amplitude as 1000 synchronized neurons! This gives that
> small
> > > systems may dominate the EEG you record.
> > >
> > > P$B<'<=<'t@<-(Bl
> > >
> > > -----Opprinnelig melding-----
> > > Fra: Makoto Miyakoshi [mailto:mataothefifth at yahoo.co.jp]
> > > Sendt: 14. april 2009 03:54
> > > Til: P$B<'<=<'t@<-(Bl Gunnar Larsson
> > > Emne: RE: [Eeglablist] Meaning of ITC
> > >
> > > Dear Pal,
> > >
> > > Thank you for your fast response and information.
> > > Neurovascular coupling is the essential phenomenon with BOLD and
> it
> > > has totally different time constant than EEG... that is fine with
> me.
> > > That said, what I'm wondering is the meaning of ITC. On the one
> hand,
> > > ERSP is a measure of EEG power, which most likely reflects sum of
> > > regional neuronal activities, which should be associated with
> BOLD
> > via
> > > neurovascular coupling (in principle). On the other hand, ITC has
> > > nothing to do with EEG power, since it is a measure of
> inter-trial
> > > phase variance, therefore it should not affect BOLD either. Then,
> > what
> > > is the meaning of ITC in contrast with ERSP/BOLD?
> > >
> > > By the way, your response does not seem to be sent to EEGLAB
> list.
> > > Why don't we re-send it to the list?
> > >
> > > Makoto
> > >
> > >
> > >
> > >
> > >
> > >
> > > --- P$B<><B<><1<><)<><)(Bl Gunnar Larsson
<Pal.Gunnar.Larsson at epilepsy.no>
> wrote:
> > >
> > > > I think you should read the paper by PL Nunez on the relation
> > > between
> > > > EEG and fMRI from 2000 (or 1999?). EEG and BOLD is very
> different
> > > > entities. Also, the EEG- parameters are direct functional
> measures
> > > > which gives responsen from a few miliseconds to some seconds
> > > > (Pfurtscheller). BOLD on the other hand, is the change in
> > > oxygenation
> > > > due to change in bloodflow due to change in energy consumption
> due
> > > > change in activity. Hence the effect is very indirect and shows
> a
> > > > maximum after some 5s. E.G. AM Dale et al has shown some nice
> use
> > > of
> > > > the BOLD and EEG/MEG so there no reason to discard one, just
> use
> > > with
> > > > care.
> > > >
> > > > P$B<><)<><?<><)<#<(<></(Bl
> > > >
> > > > -----Opprinnelig melding-----
> > > > Fra: eeglablist-bounces at sccn.ucsd.edu
> > > > [mailto:eeglablist-bounces at sccn.ucsd.edu] P$B<><)<><?<><)<#<(<></(B
vegne av
> > Makoto
> > > > Miyakoshi
> > > > Sendt: 10. april 2009 11:25
> > > > Til: eeglablist at sccn.ucsd.edu
> > > > Emne: [Eeglablist] Meaning of ITC
> > > >
> > > > Dear experts,
> > > >
> > > > Let me take a question about a basic physiology.
> > > > In my intuition, ERSP (i.e. EEG power) is related to neuronal
> > > > activation, either firing frequency or number of firing cells.
> On
> > > the
> > > > other hand, ITC (i.e. inter-trial EEG phase) is NOT directly
> > > related
> > > > to them. So, by observing ITC, we may be observing some already
> > > > systematized temporal responsibility of the given network,
> which is
> > >
> > > > too complicated and abstract to imagine, compared to the case
> of
> > > > neuronal firing simply increasing/decreasing.  Does it mean,
> then,
> > > ITC
> > > > is a totally different index than, for example, BOLD?
> > > >
> > > > Makoto
> > > > _______________________________________________
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> > >
> > >
> 
>