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# fMRI: FEEDS - FSL

A pipeline example that data from the FSL FEEDS set. Single subject, two stimuli.

You can find it at http://www.fmrib.ox.ac.uk/fsl/feeds/doc/index.html

    import os                                    # system functions

    import nipype.interfaces.io as nio           # Data i/o
    import nipype.interfaces.fsl as fsl          # fsl
    import nipype.pipeline.engine as pe          # pypeline engine
    import nipype.algorithms.modelgen as model   # model generation
    from nipype.workflows.fmri.fsl import (create_featreg_preproc,
                                           create_modelfit_workflow,
                                           create_reg_workflow)
    from nipype.interfaces.base import Bunch

## Preliminaries

Setup any package specific configuration. The output file format for FSL routines is being set to compressed NIFTI.

    fsl.FSLCommand.set_default_output_type('NIFTI_GZ')

## Experiment specific components

This tutorial does a single subject analysis so we are not using infosource and iterables

    # Specify the location of the FEEDS data. You can find it at http://www.fmrib.ox.ac.uk/fsl/feeds/doc/index.html
    feeds_data_dir = os.path.abspath('feeds/data')
    # Specify the subject directories
    # Map field names to individual subject runs.
    info = dict(func=[['fmri']],
                struct=[['structural']])

Now we create a `nipype.interfaces.io.DataSource` object and fill in the information from above about the layout of our data. The `nipype.pipeline.Node` module wraps the interface object and provides additional housekeeping and pipeline specific functionality.

    datasource = pe.Node(interface=nio.DataGrabber(outfields=['func', 'struct']),
                         name = 'datasource')
    datasource.inputs.base_directory = feeds_data_dir
    datasource.inputs.template = '%s.nii.gz'
    datasource.inputs.template_args = info
    datasource.inputs.sort_filelist = True

    preproc = create_featreg_preproc(whichvol='first')
    TR = 3.
    preproc.inputs.inputspec.fwhm = 5
    preproc.inputs.inputspec.highpass = 100/TR

    modelspec = pe.Node(interface=model.SpecifyModel(),
                        name="modelspec")
    modelspec.inputs.input_units = 'secs'
    modelspec.inputs.time_repetition = TR
    modelspec.inputs.high_pass_filter_cutoff = 100
    modelspec.inputs.subject_info = [Bunch(conditions=['Visual','Auditory'],
                                    onsets=[range(0,int(180*TR),60),range(0,int(180*TR),90)],
                                    durations=[[30], [45]],
                                    amplitudes=None,
                                    tmod=None,
                                    pmod=None,
                                    regressor_names=None,
                                    regressors=None)]

    modelfit = create_modelfit_workflow(f_contrasts=True)
    modelfit.inputs.inputspec.interscan_interval = TR
    modelfit.inputs.inputspec.model_serial_correlations = True
    modelfit.inputs.inputspec.bases = {'dgamma': {'derivs': True}}
    cont1 = ['Visual>Baseline','T', ['Visual','Auditory'],[1,0]]
    cont2 = ['Auditory>Baseline','T', ['Visual','Auditory'],[0,1]]
    cont3 = ['Task','F', [cont1, cont2]]
    modelfit.inputs.inputspec.contrasts = [cont1,cont2,cont3]

    registration = create_reg_workflow()
    registration.inputs.inputspec.target_image = fsl.Info.standard_image('MNI152_T1_2mm.nii.gz')
    registration.inputs.inputspec.target_image_brain = fsl.Info.standard_image('MNI152_T1_2mm_brain.nii.gz')
    registration.inputs.inputspec.config_file = 'T1_2_MNI152_2mm'

### Set up complete workflow

    l1pipeline = pe.Workflow(name= "level1")
    l1pipeline.base_dir = os.path.abspath('./fsl_feeds/workingdir')
    l1pipeline.config = {"execution": {"crashdump_dir":os.path.abspath('./fsl_feeds/crashdumps')}}

    l1pipeline.connect(datasource, 'func', preproc,'inputspec.func')
    l1pipeline.connect(preproc, 'outputspec.highpassed_files', modelspec, 'functional_runs')
    l1pipeline.connect(preproc, 'outputspec.motion_parameters', modelspec, 'realignment_parameters')
    l1pipeline.connect(modelspec, 'session_info', modelfit, 'inputspec.session_info')
    l1pipeline.connect(preproc, 'outputspec.highpassed_files', modelfit, 'inputspec.functional_data')
    l1pipeline.connect(preproc, 'outputspec.mean', registration, 'inputspec.mean_image')
    l1pipeline.connect(datasource, 'struct', registration, 'inputspec.anatomical_image')
    l1pipeline.connect(modelfit, 'outputspec.zfiles', registration, 'inputspec.source_files')

Setup the datasink

    datasink = pe.Node(interface=nio.DataSink(parameterization=False), name="datasink")
    datasink.inputs.base_directory = os.path.abspath('./fsl_feeds/l1out')
    datasink.inputs.substitutions = [('fmri_dtype_mcf_mask_smooth_mask_gms_mean_warp', 'meanfunc')]
    # store relevant outputs from various stages of the 1st level analysis
    l1pipeline.connect(registration, 'outputspec.transformed_files', datasink, 'level1.@Z')
    l1pipeline.connect(registration, 'outputspec.transformed_mean', datasink, 'meanfunc')

## Execute the pipeline

The code discussed above sets up all the necessary data structures with appropriate parameters and the connectivity between the processes, but does not generate any output. To actually run the analysis on the data the `nipype.pipeline.engine.Pipeline.Run` function needs to be called.

    if __name__ == '__main__':
        l1pipeline.run()

Example source code

You can download `the full source code of this example`. This same script is also included in the Nipype source distribution under the `examples` directory.