### Table of Contents

# VOI structure

## About

The VOI structure is a volume of interest along with extracted data. They are stored in **VOI*.mat** files. They are normally created by clicking on the large *V.O.I.* button after choosing *Results* in SPM2.

## Fields

Copied from **spm_regions.m**:

Y - first scaled eigenvariate of VOI {i.e. weighted mean} xY - VOI structure xY.xyz - centre of VOI {mm} xY.name - name of VOI xY.Ic - contrast used to adjust data (0 - no adjustment) xY.Sess - session index xY.def - VOI definition xY.spec - VOI definition parameters xY.XYZmm - Co-ordinates of VOI voxels {mm} xY.y - [whitened and filtered] voxel-wise data xY.u - first eigenvariate {scaled - c.f. mean response} xY.v - first eigenimage xY.s - eigenvalues xY.X0 - [whitened] confounds (including drift terms)