[FieldTrip] Signal drop out in plotting stats results

[MONALISA CHIKEZIE]

Hi All,
I am Monalisa, a neuroscience master's student doing research for my
thesis. I am relatively new to fieldtrip. I have a dataset obtained from
stats results (obtained after using dics beamformer and
parametric permutation test) which I am trying to plot the brain
activations during the experiment. My experiment had 100 participants and I
used one participant's anatomical brain as my template. However, most
activations are outside the brain. I do not know if this is a normalization
issue. Below is an example of the images I generate.
[image: image.png]

I used the code from this tutorial :
https://www.fieldtriptoolbox.org/tutorial/plotting/#plotting-data-at-the-source-level
:

My code
% Load results - get standard stat-results
load('statresults/t_statres.mat');

% Interpolation - get standard MRI
mri = ft_read_mri('Z:\EEG\sub-1_T1w.mat');


%Reslice
cfg = [];
mri = ft_volumereslice(cfg, mri);

% Interpolate the statistical data onto the resliced MRI template
cfg            = [];
cfg.downsample = 2;
cfg.parameter  = 'stat';
cfg.interpmethod    = 'nearest';
Stat_source  = ft_sourceinterpolate(cfg, t_statres , mri);

% spatially normalize the data to brain sample
cfg            = [];
cfg.nonlinear  = 'no';
cfg.spmversion = 'spm12' ;
Stat_source  = ft_volumenormalise(cfg, Stat_source);


save('statresults/Stat_source.mat', 'Stat_source');
%% DONE
fprintf('DONE\n');

Plot code
cfg = [];
cfg.method = 'ortho';
cfg.funparameter = 'stat';
cfg.maskparameter = cfg.funparameter;
cfg.funcolorlim = [-2 2];  % Adjust the color limits if needed
cfg.opacitylim = [-2 2];  % Adjust the opacity limits if needed
cfg.opacitymap = 'rampup';
cfg.anaparameter = 'anatomy';
cfg.funcolormap = 'jet';

ft_sourceplot(cfg, Stat_source);

% Add title and save the plot
title('Theta_SEMxAGE');
saveas(gcf, 'Theta_EMxAGE.png');
fprintf('DONE\n');

Previously, I used the template mri in fieldtrip; mri =
ft_read_mri('Z:\EEG\software\fieldtrip\external\spm12\toolbox\OldNorm\T1.nii');

Using the template, I got this image. However, I wanted a sharper
anatomical underlay. How do I resolve the error above?
[image: image.png]
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