Skip to contents

Convert to Current Source Density

Source: R/current_source_density.R
compute_csd.Rd

Convert an eeg_data or eeg_epochs object to using Current Source Densities. This command uses a spherical spline algorithm (Perrin et al., 1989) to compute scalp surface Laplacian/current source density estimates of scalp potentials, a reference-free measure of electrical activity that emphasises more local spatial features

Usage

compute_csd(data, ...)

# Default S3 method
compute_csd(data, ...)

# S3 method for class 'eeg_data'
compute_csd(data, m = 4, smoothing = 1e-05, scaling = 1, ...)

# S3 method for class 'eeg_epochs'
compute_csd(data, m = 4, smoothing = 1e-05, scaling = 1, ...)

Arguments

data

eeg_data or eeg_epochs object

...

Other parameters

m

smoothing constraint (higher = more rigid splines)

smoothing

lambda constant. Added to the Defaults to 1e-05

scaling

Default scaling (1) is uV / m^2. Note that this depends on the units of the electrode co-ordinates.

Methods (by class)

  • compute_csd(default): Default method to detect unknown classes.

  • compute_csd(eeg_data): Transform eeg_data to CSD

  • compute_csd(eeg_epochs): Transform eeg_data to CSD

References

  • Perrin, F., Pernier, J., Bertrand, O., Echallier, J.F. (1989). Spherical splines for scalp potential and current density mapping. Electroencephalography and Clinical Neurophysiology, 72(2), 184-187. PMID: 2464490

  • Kayser, J., Tenke, C.E. (2006). Principal components analysis of Laplacian waveforms as a generic method for identifying ERP generator patterns: I. Evaluation with auditory oddball tasks. Clinical Neurophysiology, 117(2), 348-368.

  • Kayser, J., Tenke, C.E. (2015). Issues and considerations for using the scalp surface Laplacian in EEG/ERP research: A tutorial review. International Journal of Psycholphysiology, 97(3), 189-209

Author

Matt Craddock matt@mattcraddock.com

Examples

csd_epochs <- compute_csd(demo_epochs)
plot_butterfly(csd_epochs)
#> Creating epochs based on combinations of variables: epoch_label participant_id 


# Compare the topographies of the CSD vs average referenced data
topoplot(demo_epochs, c(.2, .21))
#> Creating epochs based on combinations of variables: epoch_label participant_id 
#> Using electrode locations from data.
#> Plotting head r 95 mm

topoplot(csd_epochs, c(.2, .21))
#> Creating epochs based on combinations of variables: epoch_label participant_id 
#> Using electrode locations from data.
#> Plotting head r 95 mm