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 |
Lateralization indices |
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