neuRosim (version 0.2-14)

simTSfmri: Simulate fMRI time series

Description

Simulates an fMRI time series for the specified design and noise type.

Usage

simTSfmri(design = list(), base=0, nscan = NULL, TR = NULL, SNR=NULL,
	 noise = c("none", "white", "temporal", "low-frequency", 
	"physiological", "task-related", "mixture"), type = c("gaussian", "rician"),
	 weights, verbose = TRUE, rho = 0.2, freq.low = 128, freq.heart = 1.17, 
	freq.resp = 0.2, vee=1)

Value

A vector representing the fMRI time series.

Arguments

design

List generated by simprepTemporal specifying the design. If not specified, noise time series are generated.

base

Baseline value of the time series.

nscan

Number of scans.

TR

Repetition time in seconds.

SNR

Signal-to-noise ratio of the time series.

noise

Type of noise (white is default).

type

If noise==white, noise==task-related or noise==mixture, type of system noise (gaussian is default).

weights

If noise==mixture, vector of weights with 5 elements to specify the fraction of the noise components.

verbose

Logical indicating if warnings should be returned.

rho

If noise==temporal or noise==mixture, value of autocorrelation coefficients. The length of the vector indicates the order of the autoregressive model.

freq.low

If noise==low-frequency or noise==mixture, frequency of the low-frequency drift in seconds.

freq.heart

If noise==physiological or noise==mixture, frequency of heart rate in Hz.

freq.resp

If noise==physiological or noise==mixture, frequency of respiratory rate in Hz.

vee

If type=="rician", non-centrality parameter of the distribution.

Author

M. Welvaert

See Also

simVOLfmri, simprepTemporal

Examples

design <- simprepTemporal(totaltime=200, onsets=seq(1,200,40), 
	durations=20, effectsize=1, TR=2, hrf="double-gamma")
ts <- simTSfmri(design=design, SNR=1, noise="white")
plot(ts, type="l")
rm(design,ts)