[Eeglablist] Consequences of manual rejection on continuous data

[Makoto Miyakoshi]

Hi Alexis,

For the effect of spurious time-frequency modulations by the 'boundaries'
(i.e. time-domain data splicing), see this lecture from this time window.
https://urldefense.com/v3/__https://youtu.be/NHKIPU_T7-0?t=1861__;!!Mih3wA!BvbL3M2FKPfr96zDK2dQozcuEb3JkI1D0L68Em1CBkp9fdEZQmMUs2hdY1aatbXEZd9JhVC7dsPXleIwBuZ5zduV4as$ 

That said, at least within EEGLAB, 'boundary' event markers are treated
with special care by filter functions so that sub-windows containing the
'boundary' are excluded from the process.
So, spurious artifacts in the frequency domain should not appear.

However, when you export your data to other applications without the
'boundary' event markers, you may experience troubles when applying
frequency filters (thanks Masataka for pointing this out!)

Makoto

On Tue, Feb 4, 2025 at 12:47 PM Alexis Leiva via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Dear all,
>
>  I am performing an experiment with 4-minute blocks to analyze the power
> spectrum from the entire block but not in epochs. Then, when I manually
> reject a noisy segment from the continuous data in EEGLAB, a boundary mark
> event appears in the channel data.
>
> Now, my question: Is this method of rejection and the boundary mark
> apparition in EEGLAB a “cut and splice” implementation, inserting a kind of
> imbalance into the signal after splicing the pre- and post-noise segments?
> Knowing the possible consequences of manual rejection of my continuous data
> is critical because I don’t know if this implementation might cause a
> non-evident discontinuity of my data, some distortion, unreliable outcomes,
> or another kind of issue on the power spectrum calculus through Welch’s
> method on the entire blocks.
>
> I appreciate your help.
>
> Regards,
>
> Alexis
>
> --
>  Alexis Leiva Catalán
> Tecnólogo Médico  mención en ORL Universidad de Chile.
>  Candidato a PhD Neurociencias Pontificia Universidad Católica De Chile.
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