[Eeglablist] Which is the best way to measure the "alpha" oscillation?

[ivano triggiani]

For example Klimesch
(https://urldefense.com/v3/__https://www.sciencedirect.com/science/article/pii/S0165017398000563__;!!Mih3wA!AZCOr4FAYdEbAq0zKvlZ9d_6SmcmheTqbo97_cIu0mdk7R0v_RNHwhdog64vM5-wgvGP5u_f2pwPA6OAkbXfa7AeVlf-Cg$ )
proposes a framework where frequency bands are not defined by rigid
boundaries but are instead anchored to an individual's unique
physiological state, specifically using the Individual Alpha Frequency
(IAF) as the central anchor and the Transition Frequency (TF) as a
biomarker for the left edge of the band. This way, the Lower Alpha 1
band spans the interval from the TF to IAF - 2 Hz, representing the
entry point into alpha activity. This is followed by Lower Alpha 2,
which covers the range from IAF - 2 Hz to the IAF, and finally the
Upper Alpha (Alpha 3) band, which extends from the IAF to IAF + 2 Hz.
This subdivision reveals that the bands are not monolithic; while
Lower Alpha 1 is primarily associated with general arousal and
top-down expectancy, Lower Alpha 2 reflects specific attentional
demands, and Upper Alpha is uniquely linked to semantic memory
processing and the retrieval of information from long-term storage.

As the 1/f method can help in identifying the IAF, in my experience,
it doesn't necessarily work for the TF. Moreover, it's very important
to visually assess the adherence of the model to the actual PSD.

Ivano


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A. Ivano Triggiani, Ph.D.


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On Thu, Apr 30, 2026 at 10:17 AM Евгений Машеров via eeglablist
<eeglablist at sccn.ucsd.edu> wrote:
>
> It seems to me that there is no single, task-independent way to describe the alpha rhythm. Dividing it into subranges is justified in some cases. For example, it has been proposed to distinguish three subranges:
> Alpha-1 (low frequency): ~7.7–9.2 Hz (sometimes defined as 8–9 Hz or 8–10 Hz). Associated with relaxation processes and often predominates during decreased cognitive activity or in certain pathological conditions.
> Alpha-2 (mid frequency): ~9.3–10.5 Hz (often 10–11 Hz). Reflects active, quiet wakefulness.
> Alpha-3 (high frequency): ~10.6–12.9 Hz (often 12–13 Hz). Associated with sensory and cognitive attention processes, functionally closer to the beta rhythm.
>
> However, specifying their boundaries with an accuracy of tenths of a hertz may be related to processing features, including the sampling frequency and the number of points in the Fourier transform. For example, with a sampling frequency of 500 Hz and 1024 FFT points, the frequency step will be 0.488 Hz, meaning specifying them more accurately than half a hertz is pointless. However, if 4096 FFT points are used with the same sampling frequency, the step will be 0.122 Hz. Using window functions results in a blurring of the spectral peaks and a widening of the range boundaries. This can lead to incompatibility between data recorded under different conditions and processed with different algorithms. Additional uncertainty is introduced by the possibility of using total power or peak power, the average frequency over the range, or the frequency of the most pronounced peak.
> I believe that different approaches should be used for different classes of problems, but a single approach should be used within a single class of problems whenever possible.
>
> Your truly
>
> Eugen Masherov
>
> > Hi all,
> >
> > There have been long controversies on measuring alpha frequency power. Some
> > researchers (especially in clinical fields where electrical engineering is
> > not familiar) use frequency bands (8-12Hz or 8-13Hz) with FFT or Welch's
> > method to obtain spectral power. Other behavioral scientists prefer
> > subdivisions such as lower alpha band (8-10Hz) and higher alpha band
> > (10-12Hz). Recent advancement on FOOOF also enables the isolation of
> > periodic components to discover individual frequency peaks. There are
> > numerous other techniques that could specify the regions of eeg activities.
> > Which do you think is the best way to characterize the neurophysiological
> > activity often represented as "alpha" oscillation?
> >
> > Best Regards,
> > Jinwon Chang
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