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Compute Phase Locking Value (PLV)

Source: R/ops-connectivity.R
plv.Rd

Calculates the Phase Locking Value between channel pairs, measuring the consistency of phase difference across time.

Usage

plv(x, freq_band, channels = NULL, assay_name = NULL)

Arguments

x

A PhysioExperiment object.

freq_band

Numeric vector of length 2 specifying frequency band (Hz).

channels

Integer vector of channel indices.

assay_name

Input assay name.

Value

A numeric matrix of PLV values (channel x channel) with values ranging from 0 (random phase relationship) to 1 (perfect phase locking). Row and column names are set to channel names when available.

Details

PLV measures the consistency of the phase difference between two signals. A value of 1 indicates perfect phase locking, while 0 indicates random phase relationship.

The signals are first bandpass filtered to the specified frequency band, then the analytic signal is computed using the Hilbert transform.

References

Lachaux, J.-P., et al. (1999). "Measuring phase synchrony in brain signals." Human Brain Mapping, 8(4), 194-208. doi:10.1002/(SICI)1097-0193(1999)8:4<194::AID-HBM4>3.0.CO;2-C

See also

pli() for phase lag index, wPLI() for weighted phase lag index, coherence() for frequency-domain coherence, connectivityMatrix() for a unified connectivity interface.

Examples

set.seed(123)
pe <- PhysioExperiment(
  assays = list(raw = matrix(rnorm(4000), nrow = 1000, ncol = 4)),
  colData = S4Vectors::DataFrame(label = c("Fz", "Cz", "Pz", "Oz")),
  samplingRate = 256
)

# Compute PLV in alpha band (8-12 Hz)
plv_matrix <- plv(pe, freq_band = c(8, 12))