Detrend fMRI time series

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Description

Detrend fMRI dataset with a polynomial of given degree

Usage

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

Arguments

data

fMRI dataset of class ”fmridata

degree

Degree of the polynomial used to detrend the data. defaults to 1 (linear trends).

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

fmri.lm

Examples

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  # 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)