zscore_mu_synch: Determination of Motor Unit Synchronization from Cross...

In tweedell/motoRneuron: Analyzing Paired Neuron Discharge Times for Time-Domain Synchronization

Description

Calculates the time-domain synchronization indices CIS, k', k'-1, S, E, SI (detailed below) between the two input motor unit discharge trains based on the z-score method. First, a random uniform distribution is used to calculate a mean + 1.96 * standard deviation threshold for the experimental cross correlation histogram. Any bins within +/- 10 ms of 0 that crosses the threshold are considered to be significantly greater than expected due to chance and subsequently used for analysis. If no peaks are detected, synchronization indices of 0 are returned. Because the z-score method tests each bin individually, peak bins are not necessarily adjacent. Therefore, peak duration and peak center are returned as NA.

Usage

zscore_mu_synch(motor_unit_1, motor_unit_2, order = 1, binwidth =
  0.001, get_data = T, plot = F)

Arguments

motor_unit_1, motor_unit_2	Numeric vectors of strictly increasing numbers denoting sequential discharge times of a motor unit or neuron or any strictly increasing point process.
order	Numeric as a positive integer for the number of forward and backward orders for calculating recurrence times. Default = 1.
binwidth	Numeric as a positive for the bin allocation size for computational histogram. Default = 0.001 or 1 ms.
get_data	T/F logical for outputting motor unit data. Default is TRUE.
plot	T/F logical for outputting the cross correlation histogram. Default is FALSE.

Value

A list of lists containing motor unit data (the names of each discharge train used, number of discharges, the interspike intervals (ISI), mean ISI, and the recurrence times associated with each order) and synchronization indices. CIS = frequency of synchronized discharges. k' = ratio of total discharges in peak to expected discharges in peak. k'-1 = ratio of synchronized discharges to expected discharges in peak. S = ratio of synchronized discharges to total number of discharges of both motor units. E = ratio of synchronized discharges to non-synchronized discharges. SI = ratio of synchronized discharges to reference motor unit discharges.

References

DeFreitas, J.M., Beck, T.W., Xin, Y., Stock, M.S. (2013) Synchronization of Low- and High-Threshold Motor Units. Muscle & Nerve DOI 10.1002/mus.23978

Examples

  x <- c(0.035, 0.115, 0.183, 0.250, 0.306, 0.377, 0.455, 0.512, 0.577,
  0.656, 0.739, 0.821, 0.866, 0.950, 1.014, 1.085, 1.153, 1.213, 1.279,
  1.355, 1.431, 1.482, 1.551, 1.631, 1.692, 1.749, 1.832, 1.897, 1.964,
  2.106, 2.149, 2.229, 2.302, 2.384, 2.420, 2.505, 2.592, 2.644, 2.722,
  2.801, 2.870, 2.926, 3.011, 3.098, 2.030, 3.183, 3.252, 3.319, 3.395,
  3.469, 3.560, 3.589, 3.666, 3.744, 3.828, 3.876, 3.943, 4.020, 4.104)
  x <- sort(x)
  y <- sort(jitter(x))
  y <- round(y, digits = 3)
  zscore_mu_synch(x, y, order = 1, binwidth = 0.001, get_data = TRUE,
  plot = FALSE)

tweedell/motoRneuron documentation built on June 21, 2019, 10:43 p.m.