fmri.searchlight: Searchlight signal detection
In neuroconductor/fmri: Analysis of fMRI Experiments

Description Usage Arguments Details Value Author(s) References See Also Examples

Detection of activated regions using searchlights.

1 2	fmri.searchlight(spm, alpha = 0.05, radius, minimum.signal = 0, kind = c("abs", "squared"))

`spm`	`fmrispm` object
`alpha`	multiple test (over volume) adjusted significance level.
`radius`	radius of searchlight. Value needs to be larger or eaqual than 1.
`minimum.signal`	allows to specify a (positive) minimum value for detected signals. If minimum.signal >0 the thresholds are to conservative, this case needs further improvements.
`kind`	Kind of statistics used for aggregation over search light region. `"abs"` specifies averaging of absolute voxelwise t-statistics while `"squared"` corresponds to averaging of squares of these statistics.

The function computes mean statistics (depending on kind) over a searchlight region of radius radius. Approximate voxelwise p-values are determined with respect an empirical (simulated) distribution of the searchlight statistics under the null hypothesis a central t-distributed spm. Thresholding used FDR with rate alpha.

Object with class attributes "fmripvalue" and "fmridata"

`pvalue`	voxelwise p-value if exceeding FDR-critical value, 1 otherwise.
`weights`	voxelsize ratio
`dim`	data dimension
`hrf`	expected BOLD response for contrast (single stimulus only)