[FieldTrip] Neighbourhoods and Geodesic Arrays

[Matthew Wood]

Hello all,

My name is Matthew Wood and I'm a graduate student at The University of Texas at San Antonio. I'm starting to use cluster analysis for my EEG experiments and wanted to make sure I understood a few things about how neighborhoods in FieldTrip.

1) Our lab uses a 26 EEG electrode setup in a geodesic array (link to diagram: https://www.researchgate.net/figure/Diagram-representing-the-26-electrode-placement-in-geodesic-array_fig2_235354855). I noticed there do not exist any templates on Fieldtrip for my specific array, so I used the feature to use an image to build a layout file. If anyone happens to have a layout file I can use with more accurate measurements, I would appreciate if you could share it so that I can use that instead.

2) Since I'm building the layout and neighborhoods from scratch, I'm a little nervous about their validity. I used the "enableedit" configuration in the ft_neighbourplot function to build my neighbors (I've attached a figure here). One of the features of a geodesic array is that all electrodes are equally spaced apart. Is it correct to then assume that this should be reflected in the neighborhood structure?

3) Finally, for cluster analysis, does the distance between the neighbors matter? If so, does the fact that my layout has my electrodes placed with (seemingly) arbitrary units matter?

I appreciate any help anyone can provide!
Matthew
[https://www.researchgate.net/profile/Nicole_Wicha/publication/235354855/figure/download/fig2/AS:767255897993216@1559939469184/Diagram-representing-the-26-electrode-placement-in-geodesic-array.jpg]<https://www.researchgate.net/figure/Diagram-representing-the-26-electrode-placement-in-geodesic-array_fig2_235354855>
Figure 2. Diagram representing the 26-electrode placement in geodesic...<https://www.researchgate.net/figure/Diagram-representing-the-26-electrode-placement-in-geodesic-array_fig2_235354855>
Download scientific diagram | Diagram representing the 26-electrode placement in geodesic array. from publication: Meaning first: A case for language-independent access to word meaning in the bilingual brain | This study aimed to determine how deeply a word is processed in the bilingual brain before the word's language membership plays a role in lexical selection. In two ERP experiments, balanced Spanish-English bilinguals read lists of words and pseudowords in Spanish and English,... | Bilingual, Lexical Access and Spanish | ResearchGate, the professional network for scientists.
www.researchgate.net

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