[Eeglablist] Brain Wave Frequency Ranges: Which definition is good or correct?

[Cedric Cannard]

Hi,

This is definitely an important point. For example, alpha power can fall outside of the predefined range (e.g., 8-13 Hz) in some individuals, leading to misestimation of alpha power for these individuals. Some methods exist to detect individualized bounds (lower and upper frequency) of frequency bands, for each individual, therefore better accounting for these inter individual differences. See for example the automated, open-source method by Corcoran et al. (2017): https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_abs_10.1111_psyp.13064&d=DwIGaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=XD56o1zQC9w6OHCNeJUKvMiXTlqYKMAyXvogth6ta-nf0ULEFRiVLkIYlt6d-SjS&s=woUa6BpcEHtPek2CCiiqgP-SWlO5M2Vay6DAQNMRgVM&e= . This toolbox is designed for estimating the individual alpha frequency (IAF), but it also provides individualized lower/upper bounds detected with curve-fitting and zero-crossing methods, for any frequent band I believe (I haven’t tried it personally on other frequencies than alpha ranges).

Note also that averaging the band might present problems since different subcomponents (e.g., lower/upper alpha or local/global distributions) are contained within the alpha band (Nunez 2006). With the LIMO-EEG plugin you can look at all frequencies without assumption on specific bands, using hierarchical linear modeling and robust statistics.

Best,

Cédric

On Thu, Dec 2, 2021 at 11:36, Nilo Sarraf via eeglablist <eeglablist at sccn.ucsd.edu> wrote:

> Great question Vic! Yes there are unfortunately some inconsistencies in the body of knowledge. I am not exactly sure of the historical data as to why but can say that the differences are not disastrous.
> For example some documents say Alpha bands start at 8HZ and some say it is at 9HZ etc.
> Regardless one way to get around that is when you write your research paper that you clearly indicate that this is one of the limitations of the study and that that , within your research design, you remain consistent.
> For example in my dissertation I stuck with Alpha band of 8-15 and remained consistent throughout my data collection in that definition Alpha waves as such
> Remember, the frequencies are definited by us humans just to be able to categorize what we referring to.
> How this helps Dr Nilo Sarraf
>
> Sent from Yahoo Mail for iPhone
>
> On Wednesday, December 1, 2021, 7:14 PM, vic roc via eeglablist <eeglablist at sccn.ucsd.edu> wrote:
>
> Hi dear colleagues
>
> I see lots of quite different frequency ranges defined in different studies
> and references for the delta, theta, alpha, beta, and gamma brain waves.
> These are very very different, and in many cases inconsistent and
> controversial.
>
> Why is that so?
>
> And which range is the correct one? At least, which range is the better
> one? And why?
>
> Thanks in advance.
> Best,
> Vic
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