phaselagindex.h File Reference

Phase Lag Index (Stam, Nolte & Daffertshofer 2007) between every channel pair. More...

#include "../connectivity_global.h"
#include "abstractmetric.h"
#include "../connectivitysettings.h"
#include <QSharedPointer>
#include <QMutex>
#include <Eigen/Core>

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Classes
class	CONNECTIVITYLIB::PhaseLagIndex
	Phase Lag Index estimator (Stam et al. 2007); rejects zero-lag volume-conduction mixing. More...

Namespaces
namespace	CONNECTIVITYLIB
	Functional connectivity metrics (coherence, PLV, cross-correlation, etc.).

Detailed Description

Phase Lag Index (Stam, Nolte & Daffertshofer 2007) between every channel pair.

SPDX-License-Identifier: BSD-3-Clause Copyright (c) 2018-2026 MNE-CPP Authors

Author

Lorenz Esch loren.nosp@m.z.es.nosp@m.ch@tu.nosp@m.-ilm.nosp@m.enau..nosp@m.de; Daniel Strohmeier danie.nosp@m.l.st.nosp@m.rohme.nosp@m.ier@.nosp@m.gmail.nosp@m..com; Juan GPC jgarc.nosp@m.iapr.nosp@m.ieto@.nosp@m.mgh..nosp@m.harva.nosp@m.rd.e.nosp@m.du; Gabriel Motta gabri.nosp@m.elbe.nosp@m.nmott.nosp@m.a@gm.nosp@m.ail.c.nosp@m.om; Christoph Dinh chris.nosp@m.toph.nosp@m..dinh.nosp@m.@mne.nosp@m.-cpp..nosp@m.org

Since

0.1.0

Date

January 2018

The Phase Lag Index measures the asymmetry of the cross-spectral phase distribution about zero,

PLI_{xy}(f) = | E[ sign( Im( S_{xy}(f) ) ) ] |

with output in [0, 1]: 0 means phase differences are symmetric about 0 or pi (i.e. dominated by zero-lag mixing) and 1 means the phase lag always has the same sign (perfect, consistently lagged or leading interaction). Stam, Nolte and Daffertshofer (Human Brain Mapping, 2007) introduced PLI specifically to suppress the spurious connectivity that volume conduction and common-reference effects produce in EEG/MEG sensor-space coherence: any pair of channels driven by the same source with constant gains has a phase difference of exactly 0 or pi and therefore PLI = 0 by construction.

PLI shares the anti-leakage property of imaginary coherence but, being amplitude-independent, is more robust to amplitude artefacts at the cost of being biased upward for small samples and discontinuous around the zero-phase line. The weighted variants WeightedPhaseLagIndex and DebiasedSquaredWeightedPhaseLagIndex (Vinck et al., 2011) and the sample-bias correction UnbiasedSquaredPhaseLagIndex address those shortcomings.

Definition in file phaselagindex.h.