simulate_fmri_noise: Simulate fMRI Noise

In bbuchsbaum/fmrireg: R package for the anlysis of fmri data

Simulate fMRI Noise

Description

This function simulates realistic fMRI noise by combining:

• Temporal autocorrelation using an ARMA model

• Low-frequency drift

• Physiological noise (cardiac and respiratory)

Usage

simulate_fmri_noise(
  n,
  TR = 1.5,
  ar = c(0.3),
  ma = c(0.5),
  sd = 1,
  drift_freq = 1/128,
  drift_amplitude = 2,
  physio = TRUE,
  seed = NULL
)

Arguments

n	The number of time points in the fMRI time series
TR	The repetition time in seconds (default is 1.5)
ar	A numeric vector containing autoregressive (AR) coefficients (default is c(0.3))
ma	A numeric vector containing moving average (MA) coefficients (default is c(0.5))
sd	The standard deviation of the white noise component (default is 1)
drift_freq	Frequency of the low-frequency drift in Hz (default is 1/128)
drift_amplitude	Amplitude of the low-frequency drift (default is 2)
physio	Logical; whether to add simulated physiological noise (default is TRUE)
seed	An optional seed for reproducibility (default is NULL)

Value

A numeric vector containing the simulated fMRI noise

Examples

# Simulate noise for a 5-minute scan with TR=2s
n_timepoints <- 150  # 5 minutes * 60 seconds / 2s TR
noise <- simulate_fmri_noise(n_timepoints, TR = 2)
plot(noise, type = "l", xlab = "Time Point", ylab = "Signal")

bbuchsbaum/fmrireg documentation built on March 1, 2025, 11:20 a.m.