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Simulate fMRI Time Series

Source: R/simulate.R
simulate_bold_signal.Rd

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

simulate_bold_signal(
  ncond,
  hrf = fmrihrf::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 fmrihrf::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).

ampsd

The standard deviation of the amplitudes (default is 0).

TR

The repetition time of the fMRI acquisition (default is 1.5 seconds).

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 <- simulate_bold_signal(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")