Skip to content

Experimental / Unsupported / Legacy functions

Warning

This section should be considered as nothing more than our own internal notes and reminders on some features that are being prototyped or are under very heavy development, etc. That is, these are a) highly likely to change, b) will not necessarily use Luna's standard output mechanims, c) may be removed in future versions, and d) may be buggy, incomplete or both. Stay well clear! You've been warned! Whereas some commands listed here will (hopefully!) be elevated to be part of the main release, and more fully documented, others may remain here or be removed in future releases.

Command Description
DFA Detrended flucation analysis
ASYMM Detrended flucation analysis
A2C Annotation to cache entry
L1OUT Leave-one-out interpolation-based signal check
ED Diagnostic for electrical bridging
POL Polarity check heuristic for sleep EEG
FIP Frequency-interval plots
HR Estimate per-epoch heart rate from ECG
SPIKE Create a synthetic signal by combining part of one signal with another
ZR Calculate per-epoch Z-ratio

DFA

Implements the detrended fluctuation analysis (DFA)

Implements DFA as described by Nolte et al (2019), which adopts an efficient, Fourier-based approach to DFA, in order to study long-range temporal correlations in time series.

Briefly, a signal is split into detrended segments of length L, and the standard deviation (or fluctuations) of segments is calculated, for different length L. Under a power law, one expects a linear relationship between the log-scaled flucuations and the log of L; the slope of that line estimates the so-called Hurst exponent, which is a rescaled version of the spectral slope as estimated using other frequency-domain approaches (e.g. IRASA). See the above paper for a clear description of the full method. That paper also describes a frequency-domain approach to DFA, which is directly implemented here (currently w/ the boxcar rather than Gaussian window, however).

Parameters

Parameter Example Description
sig C3,C4 Signal(s) to analyse
n 50 Number of different window sizes to create (default 100)
min 0.1 Minimum window length (time in seconds, default 0.1)
m 2 Integer power to specify maximum window size (default 2 implies min scaled by factor 10^0 to 10^2, i.e. 0.1s to 10s)
f-lwr 10 Lower transition for band-pass filter
f-upr 15 Upper transition for band-pass filter
ripple 0.05 FIR ripple (default 0.02)
tw 2 FIR transition width (default 0.5 Hz)
epoch Report

Outputs

Epoch-level DFA statistics (strata: CH x SEC)

Variable Description
FLUCT Fluctuations
SLOPE Slopes

Epoch-level DFA statistics (option: epoch, strata: E x CH x SEC)

Variable Description
FLUCT Epoch fluctuations
SLOPE Epoch slopes

Example

to be added

ASYMM

Evaluates (regional) signal asymmetries in specifie metrics

To be completed.

A2C

Writes an annotation to a set of cache entries

Primarily an internal command for testing/development.

Documentation to be completed.

L1OUT

Leave-one-out interpolation-based signal check

ED

Heuristic method to spot electrical bridging

To be completed.

POL

Polarity checks for EEG sleep signals

Heuristics to see if signals have been fliped, based on the aysmmetrical shape of slow oscillations.

To be completed.

FIP

Frequency-interval plots

Experimental method, to be completed.

HR

A modified Pan-Tompkins algorithm for detect R peaks in the ECG

to be completed

SPIKE

Merges two signals

Parameter Example Description
from Original from signal
to Original to signal
new Label for new signal
wgt Weight

to be completed

ZR

Calculates per-epoch Z-ratio

Implementation of a simple heuristic designed to index sleep depth, as described here. Requires epoched 30-second EEG data. It is based on frequency ranges, which are different from Luna's default band definitions:

  • delta: 0.5 to 2hz
  • theta: 2.5 to 7.5 Hz
  • alpha: 8 to 12.5 Hz
  • beta: 13 to 30 Hz
Back to top