Hi Mohd,

From my experience it varies throughout the day and alertness, the peak alpha frequency (PAF) as well.

You can use eyes open and eyes closed power spectrum and see where they intersect to the decide the individual alpha frequency (see attached file).

You can also estimate the individual alpha band by the approximation of PAF - 4 Hz to PAF + 2 Hz. See Klimesch's paper attached.

Best,

Janir

Hi Janir,

Thanks for your response. I have already gone through Klimesch's paper. I would go through the other paper too.

I had one doubt that if PAF varies even during the day, why do we call it or associate it with "Individual" alpha frequency? Or is just that we use it to decide the alpha band width before a participant starts a particular cognitive experiment?

Regards,

Umair

Hi Mohd,

It's a very wide open question. We can narrow down your concern, if you can specify what your research interest is? EEG is a highly variable signal and so is IAF. Power spectral maps derived from the same individual at two different time points in a day will show variability in peak centroid and mean power not only in IAF but also in frequencies ranging from ULF to HFO. What is important is, "does that small variability make a difference to your research question or not?". Anything discussed about IAF in a couple of messages might be hugely misleading and over-exacting.

Hi Ganne,

I want to assess, say mental effort, of the participants in doing a task or a group of tasks. From what I have read, that IAF (as measured by eyes closing peak alpha frequency) varies from person to person. I'm afraid if I choose fixed frequency bands, especially for alpha (and theta), my results will get affected.

Now, my concern is how do I choose the bands:

1) IAF divides alpha band into lower and upper alpha band, while lower and upper limits are defined as +- some value of IAF (as is usually reported in literature)?

2) IAF divides divides alpha band into lower and upper alpha band, while lower limit of alpha is defined as transition frequency (TF) as calculated by, say a minute of eyes closed and a minute of eyes open? From my understanding this TF varies a lot for an individual.

3) If IAF ( and also TF) varies a lot, what value of IAF ( and TF, if I follow number 2 strategy) should I consider? Just before the task eyes closed-eyes open and then perform the task?

Thanks,

Umair