[FieldTrip] some general questions about gamma-related analyses

[Ivaylo Iotchev]

Dear all,

I am fairly new to frequency-band analyses and have dealt mostly with
transients (sleep spindles) so far. Thus forgive the maybe stupid
questions, however, one on-point professional answer could spare me
scavanging for parts across many unrelated papers.

The whole of the gamma range expands well beyond 30 Hz, the noise
threshold, and thus the first question is whether low-pass filtering below
30 Hz is at all applied when looking for gamma coherence, power etc. ...
One reason I kept the classical filter settings at first is to be
consistent across the many different analyses I apply to the same data
sets, not all of which have to do with gamma, but it dawned on me that
filtering out frequencies above 30 is probably not a good idea(?) for
gamma-related questions?

Moreover, is it acceptable to look for the point of maximum coherence
within that range, rather than average within the range? The data suggests
that the point of maximum coherence shifts across time to higher and higher
frequencies, thus I decided for the time being to report the maximum
coherence (across electrodes) value within the gamma range.

Let me know if there is any additional information I can provide to help
you help me, best wishes and regards,

Ivaylo Iotchev, PhD
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