surface_laplacian.h File Reference

Spherical-spline surface Laplacian (Current Source Density) for EEG. More...

#include "dsp_global.h"
#include <Eigen/Core>

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Classes
struct	UTILSLIB::SurfaceLaplacianResult
	Result of a surface Laplacian (CSD) computation. More...
class	UTILSLIB::SurfaceLaplacian
	Surface Laplacian / Current Source Density (CSD) transformation. More...

Namespaces
namespace	UTILSLIB
	Shared utilities (I/O helpers, spectral analysis, layout management, warp algorithms).

Detailed Description

Spherical-spline surface Laplacian (Current Source Density) for EEG.

SPDX-License-Identifier: BSD-3-Clause Copyright (c) 2026 MNE-CPP Authors

Author

Christoph Dinh chris.nosp@m.toph.nosp@m..dinh.nosp@m.@mne.nosp@m.-cpp..nosp@m.org

Since

2.2.1

Date

May 2026

The surface Laplacian ∇²V approximates the radial current density at the scalp and acts as a reference-free spatial high-pass filter: it sharpens focal cortical sources, removes the smearing introduced by volume conduction, and is largely insensitive to the choice of recording reference. The implementation follows the spherical-spline interpolation scheme of Perrin et al. (Electroenceph. Clin. Neurophysiol. 72, 1989) with the order-m Legendre series of Perrin & Bertrand (1990), so the full pipeline reduces to two dense matrix multiplications and a single channel-rank inversion.

Smoothness is governed by the spline order m (typically 3 or 4) and the diagonal regularisation λ; flexibility is the same as MNE-Python's mne.preprocessing.compute_current_source_density.

Definition in file surface_laplacian.h.