balloon: Balloon model

In neuRosim: Simulate fMRI Data

Balloon model

Description

Generates the BOLD signal based on the Balloon model of Buxton et al. (2004).

Usage

  balloon(stim, totaltime, acc, par=list(), verbose=TRUE)

Arguments

stim	Vector representing the presence/absence (1-0 coding) of a stimulus/activation in seconds.
totaltime	Total duration of stimulus vector in seconds.
acc	Microtime resolution of stimulus vector in seconds.
par	List representing the parameters of the Balloon model. The list should contain the following: kappa Inhibitory gain factor tau1 Inhibitory time constant tauf FWHM of CBF impulse response taum FWHM of CMRO2 impulse resonse deltat Delay of CBF relative to CMRO2 response n Steady-state flow metabolism relation f1 Normalized CBF response to sustained neural activation tauMTT Transit time through the balloon tau Viscoelastic time constant alpha Steady-state flow-volume relation E0 baseline O2 extraction fraction V0 baseline blood volume a1 weight for deoxyHb change a2 weight for blood volume change
verbose	If TRUE, warnings are displayed.

Details

Based on the provided stimulus boxcar function, a neural activation function is generated that enters the Balloon model to generate a BOLD response. The microtime resolution ensures a high-precision generation of the response. More details can be found in Buxton et al. (2004).

Value

Vector representing the values of the BOLD signal for the given stimulus vector and microtime resolution.

Author(s)

G. Verdoolaege, M. Welvaert

References

Buxton, RB, Uludag, K, Dubowitz, DJ and Liu, TT (2004). Modeling the hemodynamic response to brain activation. NeuroImage, 23, S220-S233.

See Also

canonicalHRF, gammaHRF

Examples

s <- rep(rep(0,10), rep(1,10), 5)
T <- 100
it <- 0.1
out <- balloon(s, T, it) 
#takes a couple of seconds due to solving of the differential equations

neuRosim documentation built on Oct. 18, 2023, 5:09 p.m.