fmri (version 1.9.12.1)

fmri.detrend: Detrend fMRI time series

Description

Detrend fMRI dataset with a polynomial of given degree

Usage

fmri.detrend(data, degree = 1, nuisance=NULL, accoef = 0)

Value

Detrended data object of class ''fmridata''.

Arguments

data

fMRI dataset of class ''fmridata''

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.

Author

Joerg Polzehl

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.

References

Polzehl, J. and Tabelow, K. (2007). fmri: A Package for Analyzing fmri Data, R News, 7:13-17.

See Also

fmri.lm

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)