FIX: Invert sulcal depth metric before passing to MSM

smriprep/workflows/surfaces.py

@@ -746,6 +746,7 @@ def init_fsLR_reg_wf(*, name="fsLR_reg_wf"):
 
 def init_msm_sulc_wf(*, sloppy: bool = False, name: str = 'msm_sulc_wf'):
     """Run MSMSulc registration to fsLR surfaces, per hemisphere."""
+    from ..interfaces.gifti import InvertShape
     from ..interfaces.msm import MSM
     from ..interfaces.workbench import (
         SurfaceAffineRegression,
@@ -789,7 +790,16 @@ def init_msm_sulc_wf(*, sloppy: bool = False, name: str = 'msm_sulc_wf'):
         name='modify_sphere',
     )
 
-    # 2) Run MSMSulc
+    # 2) Invert sulc
+    # wb_command -metric-math "-1 * var" ...
+    invert_sulc = pe.MapNode(
+        InvertShape(shape='sulc'),
+        iterfield=['shape_file', 'hemisphere'],
+        name='invert_sulc',
+    )
+    invert_sulc.inputs.hemisphere = ['L', 'R']
+
+    # 3) Run MSMSulc
     # ./msm_centos_v3 --conf=MSMSulcStrainFinalconf \
     # --inmesh=${SUB}.${HEMI}.sphere_rot.native.surf.gii
     # --refmesh=fsaverage.${HEMI}_LR.spherical_std.164k_fs_LR.surf.gii
@@ -829,18 +839,19 @@ def init_msm_sulc_wf(*, sloppy: bool = False, name: str = 'msm_sulc_wf'):
         )
         for hemi in 'LR'
     ]
-    # fmt:off
     workflow.connect([
-        (inputnode, regress_affine, [('sphere', 'in_surface'),
-                                     ('sphere_reg_fsLR', 'target_surface')]),
+        (inputnode, regress_affine, [
+            ('sphere', 'in_surface'),
+            ('sphere_reg_fsLR', 'target_surface'),
+        ]),
         (inputnode, apply_surface_affine, [('sphere', 'in_surface')]),
+        (inputnode, invert_sulc, [('sulc', 'shape_file')]),
         (regress_affine, apply_surface_affine, [('out_affine', 'in_affine')]),
         (apply_surface_affine, modify_sphere, [('out_surface', 'in_surface')]),
-        (inputnode, msmsulc, [('sulc', 'in_data')]),
         (modify_sphere, msmsulc, [('out_surface', 'in_mesh')]),
+        (invert_sulc, msmsulc, [('shape_file', 'in_data')]),
         (msmsulc, outputnode, [('warped_mesh', 'sphere_reg_fsLR')]),
-    ])
-    # fmt:on
+    ])  # fmt:skip
     return workflow