fmri_vox2reg
============

.. currentmodule:: fmri_toolbox

Description
-----------
FMRI_VOX2REG  Averages voxel data within atlas ROIs to produce ROI-level data.
Computes the mean across all voxels within each atlas ROI, producing a
compact ROI-level representation. Useful for dimensionality reduction
before connectivity or group-level analyses. Inverse of fmri_reg2vox.

Usage
-----
.. code-block:: matlab

    reg = fmri_vox2reg(vox, atlas)

Inputs
------
- **VOX**: Voxel-level data: (228453 x T) time series or (228453 x 1) map.
- **ATLAS**: Atlas number (see atlas list below). Default: 1 (AAL).

Outputs
-------
- **REG**: ROI-level data (R x T) or (R x 1), where R is the number of ROIs in the selected atlas.

Examples
--------
.. code-block:: matlab

    roi_ts = fmri_vox2reg(data, 3);         % Harvard-Oxford Cortical time series
    roi_fc = corr(roi_ts');                  % ROI x ROI FC matrix
    Atlas numbers:
    1  = AAL / MarsBar (Automated Anatomical Labeling, 116 ROIs, default)
    2  = Harvard-Oxford Subcortical Structural Atlas (21 ROIs)
    3  = Harvard-Oxford Cortical Structural Atlas (48 ROIs)
    4  = Cerebellar Atlas (MNI152, FLIRT affine, 28 ROIs)
    5  = Cerebellar Atlas (MNI152, FNIRT nonlinear, 28 ROIs)
    6  = JHU ICBM-DTI-81 White-Matter Labels (48 ROIs)
    7  = JHU White-Matter Tractography Atlas (20 ROIs)
    8  = Juelich Histological Atlas (62 ROIs)
    9  = MNI Structural Atlas (9 ROIs)
    10  = Oxford-Imanova Striatal Structural Atlas (3 ROIs)
    11  = Oxford-Imanova Striatal Connectivity Atlas, 3 sub-regions
    12  = Oxford-Imanova Striatal Connectivity Atlas, 7 sub-regions
    13  = Oxford Thalamic Connectivity Probability Atlas (25 ROIs)
    14  = Craddock Parcellation 200 ROI
    15  = Craddock Parcellation 400 ROI
    16  = Craddock Parcellation 500 ROI
    17  = Craddock Parcellation 600 ROI
    18  = Craddock Parcellation 950 ROI
    19  = Brodmann Areas (48 regions)

See Also
--------
- fmri_reg2vox
- fmri_regionmask
- fmri_vox2reg