fmri.detrend {fmri} | R Documentation |
Detrend fMRI time series
Description
Detrend fMRI dataset with a polynomial of given degree
Usage
fmri.detrend(data, degree = 1, nuisance=NULL, accoef = 0)
Arguments
data |
fMRI dataset of class ” |
degree |
Degree of the polynomial used to detrend the data. defaults to 1 (linear trends). |
nuisance |
Matrix of additional nuisance parameters to regress against. |
accoef |
Coefficient of AR(1) model used for prewhitening. default 0. |
Details
The function can be used to detrend the time series of an fMRI dataset data
(of class ”fmridata
” using polynomials. If the argument degree
is larger than 0 (default: 1) the polynomial trends up to the given degree are removed from the data. If the argument accoef
is larger than 0 (default: 0) prewhitening using an AR(1) model is performed.
Value
Detrended data object of class ”fmridata
”.
Author(s)
Joerg Polzehl polzehl@wias-berlin.de
References
Polzehl, J. and Tabelow, K. (2007). fmri: A Package for Analyzing fmri Data, R News, 7:13-17.
See Also
Examples
# Example 1
data <- list(ttt=writeBin(rnorm(32*32*32*107),raw(),4),
mask=array(1,c(32,32,32)),dim=c(32,32,32,107))
class(data) <- "fmridata"
data <- fmri.detrend(data,2)