directed_transfer_function.h File Reference

Directed Transfer Function (Kaminski & Blinowska 1991) between every channel pair, derived from a fitted MVAR transfer function. More...

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

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Classes
class	CONNECTIVITYLIB::DirectedTransferFunction
	Directed Transfer Function estimator (Kaminski & Blinowska 1991); directional, includes indirect paths. More...

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

Detailed Description

Directed Transfer Function (Kaminski & Blinowska 1991) between every channel pair, derived from a fitted MVAR transfer function.

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

2.2.0

Date

April 2026

The DTF normalises each row of the squared MVAR transfer matrix to a unit sum,

DTF_{ij}(f) = |H_{ij}(f)|^2 / sum_k |H_{ik}(f)|^2

which can be read as the fraction of the spectral power that channel i would have at frequency f that originates from channel j relative to all other channels in the model. Output is non-negative, bounded by 1, and asymmetric (DTF_{ij} != DTF_{ji} in general). Kaminski and Blinowska (Biological Cybernetics, 1991) introduced DTF for multi-channel EEG to track stimulus-driven propagation patterns across cortex, and it remains a popular reference for directed flow in multivariate spectral analysis.

Unlike PartialDirectedCoherence, DTF includes both direct and indirect causal pathways: an indirect interaction j -> k -> i shows up as a non-zero DTF_{ij}. The two metrics are therefore complementary and are usually reported alongside GrangerCausality, with all three computed from the same MvarModel fit.

Definition in file directed_transfer_function.h.