[Eeglablist] How many electrodes tolerated for interpolation?

[장진원]

Thank for your kind reply. I understand it.

Best Regards,
Jinwon

On Mon, Nov 17, 2025 at 7:23 PM fernandez luis via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> > Hi Jinwon,
> >
> > Accurate EEG channel interpolation is methodologically feasible across a
> broad spectrum of montage densities, including low-density configurations
> such as 19- and 32-channel systems, intermediate-density arrays such as 64
> channels, and high-density systems such as 128 channels. Importantly, the
> methodological validity of interpolation does not primarily depend on the
> absolute number of electrodes, but on the availability of non-artifacted
> neighboring electrodes with adequate spatial distribution surrounding the
> channel to be reconstructed.
> >
> >
> > EEG interpolation is a spatial estimation procedure in which the signal
> of an artifacted electrode is reconstructed using mathematically weighted
> contributions from the nearest clean surrounding electrodes. Accordingly,
> if the spatially adjacent electrodes are also artifacted, interpolation
> becomes unreliable or methodologically inappropriate, because the
> reconstruction process would be driven by distorted input data—violating
> key assumptions underlying spherical spline interpolation, inverse-distance
> weighting, and other spatial estimation algorithms.
> >
> >
> > In low-density montages (e.g., 19 or 32 channels), interpolation remains
> technically feasible; however, the reduced spatial sampling inherently
> limits the anatomical precision and spatial granularity of the
> reconstructed signal. Nevertheless, interpolation in these systems can
> yield clinically acceptable results as long as the electrodes used as
> sources for reconstruction are clean, stable, and sufficiently distributed
> around the artifacted location.
> >
> >
> > Intermediate-density systems such as 64-channel EEG offer improved
> spatial resolution that allows more accurate reconstruction of missing
> channels due to enhanced scalp coverage. High-density montages,
> particularly 128-channel EEG systems, provide dense and homogeneous spatial
> sampling, minimizing interpolation error and generating reconstructions
> that are more physiologically plausible and quantitatively reliable. This
> level of spatial resolution is advantageous for applications requiring
> high-fidelity scalp mapping, microstate analysis, connectivity estimation,
> and source localization.
> >
> >
> > Despite differences in resolution across montage densities, a
> fundamental methodological requirement remains invariant: interpolation
> must be performed exclusively using clean, non-artifacted surrounding
> electrodes. Reconstruction based on artifacted neighbors compromises the
> physiological validity of the estimated signal and undermines the
> mathematical assumptions intrinsic to spatial interpolation algorithms.
> >
> >
> > Technical Comparison: Conventional vs. High-Density EEG Interpolation
> >
> >
> > 1. Interpolation in conventional EEG (19–32 channels)
> >
> >
> > Low-density EEG systems rely on sparse spatial sampling, which imposes
> several methodological constraints:
> >
> >
> > • Wide inter-electrode spacing
> >
> > • Higher vulnerability to local contamination
> >
> > • Reduced capacity to capture rapid spatial changes
> >
> > • Acceptable but limited reliability
> >
> >
> > 2. Interpolation in high-density EEG (64–128 channels)
> >
> >
> > High-density EEG (HD-EEG) significantly enhances the reliability of
> interpolation due to:
> >
> >
> > • Dense and homogeneous spatial sampling
> >
> > • Robustness to isolated corrupted channels
> >
> > • Improved modeling of spatial gradients
> >
> > • Near-physiological reconstruction in 128-channel systems
> >
> > Best
> > Luis Fernandez, MSc
> > Clinical Neuropsychologist
> >
>
> > El 17 nov 2025, a las 20:41, 장진원 via eeglablist <
> eeglablist at sccn.ucsd.edu> escribió:
> >
> > Hi all,
> >
> > I'm a clinical psychiatrist, so I am not really familiar with engineering
> > concept of interpolation. I believe in high-density setting (128 channel)
> > interpolation of a few channels are acceptable, but what if more than 10
> > bad channels in 64 channel setting? Is it tolerable or detrimental for
> > maintenance of true signal?
> >
> > Best regards,
> > Jinwon Chang
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