WIP: Adds support for fNIRS data to set_montage and new standard artinis montage

doc/changes/latest.inc

@@ -183,6 +183,8 @@ Enhancements
 
 - Improve performance of :func:`mne.set_bipolar_reference` (:gh:`9270` by `Martin Schulz`_)
 
+- Add support for setting montages on fNIRS data, with built in standard montages for Artinis OctaMon and Artinis Brite23 devices (:gh:`9141` by `Johann Benerradi`_, `Robert Luke`_ and `Eric Larson`_)
+
 Bugs
 ~~~~
 - Fix bug with :func:`mne.viz.plot_evoked_topo` where set ylim parameters gets swapped across channel types. (:gh:`9207` by |Ram Pari|_)

mne/channels/_standard_montage_utils.py

@@ -73,7 +73,7 @@ def _biosemi(basename, head_size):
     return _read_theta_phi_in_degrees(fname, head_size, fid_names)
 
 
-def _mgh_or_standard(basename, head_size):
+def _mgh_or_standard(basename, head_size, coord_frame='unknown'):
     fid_names = ('Nz', 'LPA', 'RPA')
     fname = op.join(MONTAGE_PATH, basename)
 
@@ -103,7 +103,7 @@ def _mgh_or_standard(basename, head_size):
     lpa *= scale
     rpa *= scale
 
-    return make_dig_montage(ch_pos=ch_pos, coord_frame='unknown',
+    return make_dig_montage(ch_pos=ch_pos, coord_frame=coord_frame,
                             nasion=nasion, lpa=lpa, rpa=rpa)
 
 
@@ -144,6 +144,10 @@ def _mgh_or_standard(basename, head_size):
                                  basename='standard_prefixed.elc'),
     'standard_primed': partial(_mgh_or_standard,
                                basename='standard_primed.elc'),
+    'artinis-octamon': partial(_mgh_or_standard, coord_frame='mri',
+                               basename='artinis-octamon.elc'),
+    'artinis-brite23': partial(_mgh_or_standard, coord_frame='mri',
+                               basename='artinis-brite23.elc'),
 }
 
 

mne/channels/data/montages/artinis-brite23.elc

@@ -0,0 +1,48 @@
+# ASA optode file
+ReferenceLabel	avg
+UnitPosition	mm
+NumberPositions=	21
+Positions
+-4.62 82.33 -45.74
+79.66 -18.72 -45.89
+-81.41 -17.18 -45.56
+65.18 27.28 35.31
+48.62 59.71 22.68
+18.95 72.41 38.32
+-3.97 79.74 30.28
+-25.96 72.19 35.16
+-52.51 60.53 14.54
+-66.37 32.04 31.08
+76.10 -0.29 31.24
+65.61 -0.26 56.15
+64.93 42.43 8.29
+43.32 46.36 50.77
+21.58 82.45 1.06
+-2.91 59.57 61.59
+-29.62 79.35 2.38
+-48.13 44.76 49.15
+-67.68 43.26 -3.18
+-65.37 4.89 56.36
+-77.24 5.88 27.58
+Labels
+Nz
+RPA
+LPA
+D1
+D2
+D3
+D4
+D5
+D6
+D7
+S1
+S2
+S3
+S4
+S5
+S6
+S7
+S8
+S9
+S10
+S11

mne/channels/data/montages/artinis-octamon.elc

@@ -0,0 +1,32 @@
+# ASA optode file
+ReferenceLabel	avg
+UnitPosition	mm
+NumberPositions=	13
+Positions
+0.96 83.56 -48.63
+80.25 -19.67 -43.88
+-82.58 -20.09 -43.10
+47.77 65.28 7.28
+-46.45 67.76 8.81
+63.88 34.84 28.34
+64.96 45.02 -10.31
+22.07 74.86 31.03
+17.84 84.96 -10.84
+-10.81 77.96 32.10
+-15.96 85.24 -7.41
+-61.78 40.78 29.92
+-65.28 48.14 -10.73
+Labels
+Nz
+RPA
+LPA
+D1
+D2
+S1
+S2
+S3
+S4
+S5
+S6
+S7
+S8

mne/channels/montage.py

@@ -33,7 +33,7 @@
                                 _get_data_as_dict_from_dig)
 from ..io.meas_info import create_info
 from ..io.open import fiff_open
-from ..io.pick import pick_types
+from ..io.pick import pick_types, _picks_to_idx
 from ..io.constants import FIFF, CHANNEL_LOC_ALIASES
 from ..utils import (warn, copy_function_doc_to_method_doc, _pl, verbose,
                      _check_option, _validate_type, _check_fname, _on_missing,
@@ -52,7 +52,8 @@
     'easycap-M1', 'easycap-M10',
     'mgh60', 'mgh70',
     'standard_1005', 'standard_1020', 'standard_alphabetic',
-    'standard_postfixed', 'standard_prefixed', 'standard_primed'
+    'standard_postfixed', 'standard_prefixed', 'standard_primed',
+    'artinis-octamon', 'artinis-brite23'
 ]
 
 
@@ -725,6 +726,47 @@ def _get_montage_in_head(montage):
         return transform_to_head(montage.copy())
 
 
+def _set_montage_fnirs(info, montage):
+    """Set the montage for fNIRS data.
+
+    This needs to be different to electrodes as each channel has three
+    coordinates that need to be set. For each channel there is a source optode
+    location, a detector optode location, and a channel midpoint that must be
+    stored. This function modifies info['chs'][#]['loc'] and info['dig'] in
+    place.
+    """
+    from ..preprocessing.nirs import (_channel_frequencies,
+                                      _channel_chromophore,
+                                      _check_channels_ordered)
+    # Validate that the fNIRS info is correctly formatted
+    freqs = np.unique(_channel_frequencies(info))
+    if freqs.size > 0:
+        picks = _check_channels_ordered(info, freqs)
+    else:
+        picks = _check_channels_ordered(info,
+                                        np.unique(_channel_chromophore(info)))
+
+    # Modify info['chs'][#]['loc'] in place
+    num_ficiduals = len(montage.dig) - len(montage.ch_names)
+    for ch_idx in picks:
+        ch = info['chs'][ch_idx]['ch_name']
+        source, detector = ch.split(' ')[0].split('_')
+        source_pos = montage.dig[montage.ch_names.index(source)
+                                 + num_ficiduals]['r']
+        detector_pos = montage.dig[montage.ch_names.index(detector)
+                                   + num_ficiduals]['r']
+
+        info['chs'][ch_idx]['loc'][3:6] = source_pos
+        info['chs'][ch_idx]['loc'][6:9] = detector_pos
+        midpoint = (source_pos + detector_pos) / 2
+        info['chs'][ch_idx]['loc'][:3] = midpoint
+
+    # Modify info['dig'] in place
+    info['dig'] = montage.dig
+
+    return info
+
+
 @fill_doc
 def _set_montage(info, montage, match_case=True, match_alias=False,
                  on_missing='raise'):
@@ -758,6 +800,7 @@ def _set_montage(info, montage, match_case=True, match_alias=False,
 
     if isinstance(montage, DigMontage):
         mnt_head = _get_montage_in_head(montage)
+        del montage
 
         def _backcompat_value(pos, ref_pos):
             if any(np.isnan(pos)):
@@ -862,6 +905,7 @@ def _backcompat_value(pos, ref_pos):
 
         for name, use in zip(info_names, info_names_use):
             _loc_view = info['chs'][info['ch_names'].index(name)]['loc']
+            # Next line modifies info['chs'][#]['loc'] in place
             _loc_view[:6] = _backcompat_value(ch_pos_use[use], eeg_ref_pos)
 
         del ch_pos_use
@@ -890,14 +934,23 @@ def _backcompat_value(pos, ref_pos):
             # in the old dig
             if ref_dig_point in old_dig:
                 digpoints.append(ref_dig_point)
+        # Next line modifies info['dig'] in place
         info['dig'] = _format_dig_points(digpoints, enforce_order=True)
 
         if mnt_head.dev_head_t is not None:
+            # Next line modifies info['dev_head_t'] in place
             info['dev_head_t'] = Transform('meg', 'head', mnt_head.dev_head_t)
 
+        # Handle fNIRS with source, detector and channel
+        fnirs_picks = _picks_to_idx(info, 'fnirs', allow_empty=True)
+        if len(fnirs_picks) > 0:
+            info = _set_montage_fnirs(info, mnt_head)
+
     else:  # None case
+        # Next line modifies info['dig'] in place
         info['dig'] = None
         for ch in info['chs']:
+            # Next line modifies info['chs'][#]['loc'] in place
             ch['loc'] = np.full(12, np.nan)
 
 
@@ -1361,6 +1414,10 @@ def make_standard_montage(kind, head_size=HEAD_SIZE_DEFAULT):
                           MGH (60+3 locations)
     mgh70                 The (newer) 70-channel BrainVision cap used at
                           MGH (70+3 locations)
+
+    artinis-octamon       Artinis OctaMon fNIRS (8 sources, 2 detectors)
+
+    artinis-brite23       Artinis Brite23 fNIRS (11 sources, 7 detectors)
     ===================   =====================================================
 
     .. versionadded:: 0.19.0

mne/channels/tests/test_montage.py

@@ -1498,7 +1498,7 @@ def test_read_dig_hpts():
 
 def test_get_builtin_montages():
     """Test help function to obtain builtin montages."""
-    EXPECTED_NUM = 24
+    EXPECTED_NUM = 26
     assert len(get_builtin_montages()) == EXPECTED_NUM