# This subjects ICA components have left me with an uneasy feeling

**URL:** <https://mne.discourse.group/t/this-subjects-ica-components-have-left-me-with-an-uneasy-feeling/6397>\
**Category:** Support & Discussions\
**Created:** [February 22, 2023, 4:10pm UTC](https://mne.discourse.group/t/this-subjects-ica-components-have-left-me-with-an-uneasy-feeling/6397 "2023-02-22T16:10:21Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![Steve\_Sizzou](https://avatars.discourse-cdn.com/v4/letter/s/ba8739/32.png) [@Steve\_Sizzou](https://mne.discourse.group/u/Steve_Sizzou)\
**Post date:** [February 22, 2023, 4:10pm UTC](https://mne.discourse.group/t/this-subjects-ica-components-have-left-me-with-an-uneasy-feeling/6397/1 "2023-02-22T16:10:21Z")

</div>

MNE 1.3.0  
MacOS BigSur 11.6.7

 ![image](https://global.discourse-cdn.com/free1/uploads/mne/original/2X/9/9c41c7bb651b33a3bd3a3717624c6b82c4af557d.jpeg)

Have you ever seen something so freaky? It’s like this subject’s brain activity is sending a message from another dimension. Here’s my code & data:

```python
import mne
from mne.preprocessing import ICA
raw = mne.io.read_raw_eeglab('data/participant/sub-03_task-rsvp_continuous.set', preload=True,
                             montage_units="dm")
raw.set_montage("standard_1005")
raw.filter(0.01, 100.0, method='iir', n_jobs=-1)
filt_raw = raw.copy().filter(l_freq=1., h_freq=None)
ica = ICA(n_components=63, max_iter='auto', random_state=97)
ica.fit(filt_raw)
ica.plot_components()

```

Data from a freely available source:  
[https://openneuro.org/datasets/ds003825/versions/1.2.0](https://openneuro.org/datasets/ds003825/versions/1.2.0)  
This is subject 3 in derivatives/eeglab.

---

<div class="post-metadata">

**Author:** ![cbrnr](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/cbrnr/32/1409_2.png) [@cbrnr](https://mne.discourse.group/u/cbrnr)\
**Post date:** [February 22, 2023, 4:30pm UTC](https://mne.discourse.group/t/this-subjects-ica-components-have-left-me-with-an-uneasy-feeling/6397/2 "2023-02-22T16:30:33Z")

</div>

😄 This looks scary indeed! I’d start with verifying that the raw data looks sane and doesn’t contain huge artifacts. I sometimes get such components when there is an extremely large spike or other weird stuff somewhere in the data. I also wonder why you have Cz in your topoplots when this is supposed to be the reference channel (according to the docs).

---

<div class="post-metadata">

**Author:** ![mscheltienne](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/mscheltienne/32/827_2.png) [@mscheltienne](https://mne.discourse.group/u/mscheltienne)\
**Post date:** [February 22, 2023, 6:36pm UTC](https://mne.discourse.group/t/this-subjects-ica-components-have-left-me-with-an-uneasy-feeling/6397/3 "2023-02-22T18:36:53Z")

</div>

Wow nice ones ahah  
I would add that you could remove the reference from the `inst` used to fit the data, if it is flat. i.e. keep it if you referenced the data e.g. to a common average. And secondly, you could set `n_components=None`, you might be fitting too many components.

Mathieu

---

<div class="post-metadata">

**Author:** ![Steve\_Sizzou](https://avatars.discourse-cdn.com/v4/letter/s/ba8739/32.png) [@Steve\_Sizzou](https://mne.discourse.group/u/Steve_Sizzou)\
**Post date:** [February 23, 2023, 10:16am UTC](https://mne.discourse.group/t/this-subjects-ica-components-have-left-me-with-an-uneasy-feeling/6397/5 "2023-02-23T10:16:01Z")

</div>

Thanks! Yeah I tried with a small, random sub sample of the raw data and they then look completely different. I find that the raw.plot() is quite slow and sometimes crashes though, which means I can’t really scroll through the entire raw to look for components, do you maybe have any tips for finding particularly bad chunks of raw data?

---

<div class="post-metadata">

**Author:** ![Steve\_Sizzou](https://avatars.discourse-cdn.com/v4/letter/s/ba8739/32.png) [@Steve\_Sizzou](https://mne.discourse.group/u/Steve_Sizzou)\
**Post date:** [February 23, 2023, 10:24am UTC](https://mne.discourse.group/t/this-subjects-ica-components-have-left-me-with-an-uneasy-feeling/6397/6 "2023-02-23T10:24:10Z")

</div>

Great thanks, the data was referenced to an average reference. I cut off the first and last 500 seconds from the raw and this gets rid of the disturbing plots, so now I can finally sleep at night ☺