sim_ts: Simulate fMRI Time Series

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

Simulate fMRI Time Series

Description

This function simulates an fMRI time series for multiple experimental conditions with specified parameters. It generates a realistic event-related design with randomized inter-stimulus intervals and condition orders.

Usage

sim_ts(
  ncond,
  hrf = HRF_SPMG1,
  nreps = 12,
  amps = rep(1, ncond),
  isi = c(3, 6),
  ampsd = 0,
  TR = 1.5
)

Arguments

ncond	The number of conditions to simulate.
hrf	The hemodynamic response function to use (default is HRF_SPMG1).
nreps	The number of repetitions per condition (default is 12).
amps	A vector of amplitudes for each condition (default is a vector of 1s with length ncond).
isi	A vector of length 2 specifying the range of inter-stimulus intervals to sample from (default is c(3, 6) seconds).
TR	The repetition time of the fMRI acquisition (default is 1.5 seconds).
apmsd	the standard deviation of the amplitudes (default is 0).

Value

A list with the following components:

• onset: A vector of the onset times for each trial

• condition: A vector of condition labels for each trial

• mat: A matrix containing the simulated fMRI time series:

  • Column 1: Time points (in seconds)

  • Columns 2:(ncond+1): Simulated BOLD responses for each condition

Examples

# Simulate 3 conditions with different amplitudes
sim <- sim_ts(ncond = 3, amps = c(1, 1.5, 2), TR = 2)

# Plot the simulated time series
matplot(sim$mat[,1], sim$mat[,-1], type = "l", 
        xlab = "Time (s)", ylab = "BOLD Response")

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