Delta/Alpha Ratio (DAR)

Computes the delta-to-alpha band-power ratio per channel (or per region), a quantitative-EEG stroke marker whose elevation tracks ischaemic slowing (Finnigan et al. 2016). Band powers use a Welch estimator for a stable spectrum. Each ratio is returned as a reliability-characterised physioBiomarker carrying provenance (band, method, software version), reliability placeholders, and - when age (and montage) are supplied - a published reference range from normativeLookup so the value prints its normative percentile.

Usage

eegDAR(
  x,
  delta = c(1, 4),
  alpha = c(8, 13),
  regions = NULL,
  method = "welch",
  age = NULL,
  montage = NULL,
  reliability = list(icc = NA_real_, sem = NA_real_),
  assay_name = NULL
)

Arguments

x

A PhysioExperiment object with 2D EEG data.

delta

Numeric length-2 delta band in Hz (default: c(1, 4)).

alpha

Numeric length-2 alpha band in Hz (default: c(8, 13)).

regions

Optional named list mapping a region name to a character vector of channel labels; band powers are averaged within each region. When NULL (default) one biomarker is returned per channel.

method

Spectral estimator passed to the band-power routine (default: "welch").

age

Optional numeric age used to select the normative reference row.

montage

Optional character montage for the normative lookup.

reliability

Named list of reliability indices to attach (default: icc and sem placeholders).

assay_name

Input assay name (default: the default assay).

Value

A named list of PhysioBiomarker objects, one per channel or region.

References

Finnigan, S., Wong, A., & Read, S. (2016). Defining abnormal slow EEG activity in acute ischaemic stroke: Delta/alpha ratio as an optimal QEEG index. Clinical Neurophysiology, 127(2), 1452-1459.

See also

eegBSI(), eegSlowing(), eegQEEG(), PhysioCore::physioBiomarker(), PhysioCore::normativeLookup()

Examples

if (FALSE) { # \dontrun{
pe <- make_eeg(n_time = 5000, n_channels = 19, sr = 250)
dar <- eegDAR(pe, age = 60)
dar[["C3"]]
} # }