Electromechanical Delay via Cross-Correlation

Computes the electromechanical delay (EMD) between EMG and kinematic signals for muscle-bone pairs connected in the MSK hypergraph. Optionally correlates EMD with MSK network distance.

Usage

neuromechElectromechanicalDelay(
  emg,
  kinematics,
  hg = NULL,
  emg_mapping = NULL,
  kin_mapping = NULL,
  sr = NULL,
  max_lag_ms = 200,
  window_sec = NULL,
  n_perm = 999L
)

Arguments

emg

EMG data: SummarizedExperiment, matrix (time x channels), or vector.

kinematics

Kinematic data: matrix (time x segments) or SummarizedExperiment.

hg

An MSKHypergraph object (NULL loads default).

emg_mapping

Optional pre-computed data.frame from emgToMSKMapping().

kin_mapping

Optional pre-computed data.frame from mocapToMSKMapping() or imuToMSKMapping().

sr

Optional sampling rate (overrides detected value).

max_lag_ms

Numeric, maximum lag in milliseconds (default: 200).

window_sec

Optional numeric, window size in seconds for sliding window EMD analysis (NULL for global only).

n_perm

Integer, number of permutations for correlation test (default: 999).

Value

A list with:

emd

Data.frame with muscle, bone, emd_ms, peak_correlation per pair

network_distance

Corresponding MSK shortest path distance

correlation

Pearson correlation between EMD and network distance

p_value

Permutation p-value for the correlation

time_varying

Data.frame with per-window EMD (if window_sec set)

Examples

set.seed(1)
emg <- matrix(abs(rnorm(300 * 4)), 300, 4)
colnames(emg) <- c("Biceps Brachii", "Deltoid", "Trapezius", "Triceps Brachii")
set.seed(4)
kin <- matrix(cumsum(rnorm(300)) + sin(seq(0, 6, length.out = 300)), 300, 1)
colnames(kin) <- "elbow"
result <- neuromechElectromechanicalDelay(emg, kin, sr = 1000, n_perm = 19)
result
#> $emd
#> [1] muscle           bone             muscle_idx       bone_idx        
#> [5] emd_ms           peak_correlation
#> <0 rows> (or 0-length row.names)
#> 
#> $network_distance
#> numeric(0)
#> 
#> $correlation
#> [1] NA
#> 
#> $p_value
#> [1] NA
#> 
#> $time_varying
#> NULL
#>