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

compute_csd(data, ...)

# S3 method for default
compute_csd(data, ...)

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

# S3 method for 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)

  • default: Default method to detect unknown classes.

  • eeg_data: Transform eeg_data to CSD

  • eeg_epochs: Transform eeg_data to CSD

References

[1] 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 [2] 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. [3] 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

Examples

csd_epochs <- compute_csd(demo_epochs) plot_butterfly(csd_epochs)