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Dynamical states in ERP-data?

F. Frank LeFever flefever at ix.netcom.com
Sun Aug 1 00:19:28 EST 1999

Well, maybe I won't tell you THAT soon!

I really do not get into that level of analysis, so cannot say anything
very substantial regarding low vs. high- dimensional states and ERP.

I do have some bits and pieces of information, which telling you might
be like carrying coals to Newcastle (I was in Newcastle, in a side trip
from Durham a few years ago, but resisted the temptation to carry any

I believe John Thatcher's work might be relevantt to this; but my
impression is that he deals with ongoing EEG, not ERP.

Perhaps the work of Rudolfo LLinas (I hate the usage "Ll", prefer "LL")
and others re (nominally) 40Hz activity would be relevant.

I may be showing my ignorance re low vs. dimensional states, but except
for the organization involved in 40Hz binding together of disparate
sites, one usually associates organization with sleep, pathological
states (e.g. seizure, etc.)  (I'm jumping to the conclusion that this
soort of organization can be described in just a few parameters and
would therefore exemmplify "low-dimensional" sttates, but maybe I do
not understand the terms so well)

IF I am interpreting these terms/understanding these concepts
correctly, my query a few weeks (months?) ago regarding "theta" might
be relevant.  Hippocampal theta can be specified simply, I think (i.e.
it is EEG activity within a very slow range, in contrast to the high
reange of 40Hz), and has been associated witth cognitive processes
(e.g. memory formattion?) as has been another "theta"
(thalamo-frontal??) found during problemm solving(?); but my query had
to do with "theta" of pathology--same simple description ("c. 6 Hz"),
but quite antithetical to cognition.

Well, hope you can find something oof heuristic value in this, anyway..

F. Frank LeFever, Ph.D.
New York Neuropsychology Group

In <37A049F4.CCBFEC28 at cns.mpg.de> Axel Hutt <hutt at cns.mpg.de> writes: 
>"F. Frank LeFever" wrote:
>> I'll tell you as soon as you tell me what is a "low-dimensional
>> state".
>"low-dimensional" means only few parameters suffice to describe
>the temporal and spatial behaviour of ERP-signals in time windows
>of cognitive processes.
>Normal EEG is known to be "high-dimensional" means there are know
>specific patterns in time or space, no order parameters, just not
>organized. Thus the question is if any organization in the brain is 
>found during cognitive processes.

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