EEG gamma rhythm and/or fractal EEG analysis

[Erik Nordh <erik.nordh@NEURO.UMU.SE>]

In response to John Shaw's posting, where the question of EEG gamma rhythm
studies was raised, one might notice that analyses of brain activity in the
frequency range 50-60 Hz in a "clinical setting" are hampered by the not
too uncommon problem of sine-vawe interference from electric equipment etc
in the surroundings. Even if fairly steep filters are being used there is
always a risk of that the analyses are critically affected, either by the
noise or by the cut-off properties of the filtering. Also, as long as no
clearcut "clinical" significance of these rythms have been shown, I think
that many of us who are primarily doing EEG recordings in clinical routine
hesitate to bring the matter up with colleagues that are not particularly
interested. Hence, there is a mutual "Catch 22"-situation; no accepted
clinical need for the analysis and no studies being done showing the
possible use of such analysis...

Another aspect of "extended EEG analyses", which I have not yet seen any
reports on, is fractal signal analysis (or applied "chaos mathematics") of
EEG signals. This concept have brought somewhat of a revolution into not
only mathematics, but to a variety of disciplines (se e.g. the article "A
Fractal Walk Down Wall Street" in a recent issue of Scientific American).
The theories have also had implications for biomedicine, mainly (?) in
cardiac physiology where work have been done in areas ranging from
evaluation of ECG's to the emergence of "random driven" ecuipment for use
in acute HLR treatment. However, so far I've not seen any more extensive
studies in this respect withing EEG evaluations. Is someone else better
informed?

The latter method might perhaps lead to a revival of the EEG as a tool for
analyses of brain function?

Regards
/Erik