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Table 1 Common measures of synchrony and directionality in neuronal communication

From: Lack of redundancy between electrophysiological measures of long-range neuronal communication

Category

Acronym

Metric

Description

References

Non-directed coupling, synchrony

Coherence (magnitude)

Magnitude of the complex cross-spectrum

[1, 2]

ImC

Imaginary part of coherence

Discards the real component of the cross-spectrum

[3]

PLI

Phase Lag Index

Disregards the magnitude of the cross-spectrum and averages the sign of phase differences

[4]

wPLI

Weighted phase lag index

Phase lags are weighed by the magnitude of the imaginary component of the cross-spectrum

[5]

PLV

Phase-locking value

Circular resultant vector length of the phase differences

[6]

PPC

Pairwise phase consistency

Computed based on the distribution of phase differences

[7]

Directed (lead/lag, LFP-based)

Coherence phase angle

Angle of the complex cross-spectrum

[8, 9]

CC

Cross-amplitude coupling, amplitude cross-correlation

Instantaneous amplitudes of two filtered LFPs are cross-correlated and the lag at which the peak occurred is determined

[10]

Directed (causal influence)

GC

Granger causality

Quantifies if the past of one time series can predict the future of another time series using autoregressive modelling

[11,12,13,14]

npGC

Non-parametric Granger causality

Granger causality based on spectral matrix factorization

[15]

PDC

Partial directed coherence

Normalized metric based on GC that measures direct influence from one time series to another

[16]

DTF

Direct transfer function

Adaptation to multiple input variables closely related to PDC

[17, 18]

Directed (phase-locking of local activity)

SPC, MRL

Spike-phase coupling, Mean resultant vector length

Circular concentration of the phase distribution at which spikes occurred

[2, 19,20,21]

PAC, CFC, MI

Phase amplitude coupling, cross-frequency coupling, modulation index

Modulation of the amplitude of high-frequency oscillations in one area by the phase of low-frequency oscillations from another area

[22,23,24]

Directed (lead lag, spike-based)

Phase angle of MRL

Mean phase at which spikes occurred

[20]

Phase-shifted MRL

Calculation of the MRL based on phases at shifted lags

[2, 19]