[Eeglablist] Meaning of ITC

Thu Apr 16 09:56:49 PDT 2009

   Dear all,

   After reading some of the comments I just like to give you some papers
and links that may help you

http://sulcus.berkeley.edu/wjf/AB.Genesis.of.Meaning.pdf
http://www.math.nmsu.edu/~jlakey/papers/emd_eeg_revised.pdf
http://coewww.rutgers.edu/classes/bme/bme450/introduction/EEGMRI_Chapter.pdf
http://www.kyb.mpg.de/publications/pdfs/pdf2893.pdf
http://www.ai.uga.edu/tonysnod/neuroscience/Logothetis_et_al(2001).pdf
http://www.helsinki.fi/fgsn/courses/kuvat/Logothetis_Wandell2004.pdf

  Best regards


Carlos


2009/4/16 Makoto Miyakoshi <mataothefifth at yahoo.co.jp>

> Dear Pal,
>
> >From this reply I hope our communication is normally logged on the
> eeglablist.
>
> Yes, the Bereitshcafts Potentials seems a good example, if the potential
> were constructed by phase locking (I'm not sure on this point). By the way,
> could you specify 'Alan Gevins works from around 1984' which I could not
> find? I want to take a look at the illustrations.
>
> The immediate meaning of ITC is 'trial-by-trial EEG phase coherency at a
> certain IC/scalp channel, time bin, and frequency range, is likely to be
> this much'. It only reflects (at least in princiele) the timing of neural
> firing (large portion of neurons), and does not reflect the amount of it
> (though ERSP and BOLD do, in constrast, in my understanding). Certainly, a
> physiological meaning of ITC is a event-related 'timing' of neuronal
> firing.
>
> So, my question again may be: what is the 'psychological' meaning of ITC
> increase/decrease, given that it does not reflect increase/decrease of
> involved neuronal activity? Maybe I'm too much used to a simple schema that
> associates ERSP/BOLD increase with 'activation' of a certain portion of
> neurons.
>
> Makoto
>
>
>
>
>
>
>
> --- P $B>-%% (Bl Gunnar Larsson <Pal.Gunnar.Larsson at epilepsy.no> wrote:
>
> > 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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> > > > >
> > > >
> > > >
> >
> >
>
>
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-- 
Dr. Carlos A. Novo Olivas
Neurociencia Clínica
Neurofisiología Clínica

Oficina: 8143 0754
Cel: 8115 784089
www.neuroscopic.com
www.ania.org.mx
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