# mne.Epochs: response events disappear when locking on stimulus events **URL:** \ **Category:** Mailing List Archive (read-only)\ **Tags:** list-archive\ **Created:** [May 31, 2020, 8:22pm UTC](https://mne.discourse.group/t/mne-epochs-response-events-disappear-when-locking-on-stimulus-events/2207 "2020-05-31T20:22:03Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [May 31, 2020, 8:22pm UTC](https://mne.discourse.group/t/mne-epochs-response-events-disappear-when-locking-on-stimulus-events/2207/1 "2020-05-31T20:22:03Z")
External Email - Use Caution Hi Community, I would like to segment my EEG data into epochs of -300 to 1900 ms relative to stimulus onset, and keep response triggers in these epochs. I then computed: epochs = mne.Epochs(raw\_EEG\_av\_ref\_filt, raw\_events, events\_stim, tmin=-0.3, tmax=1.9, baseline=(-.3, 0), preload=True) However, the epoched data only contain stimulus events (events\_stim), and response events have been dropped. Is there a way to keep response events? In addition, is it possible to epoch again my 'epochs' object (say I want to lock the signal -100 to +100 ms relative to the response)? Best, Mat -------------- next part -------------- An HTML attachment was scrubbed... URL: [http://mail.nmr.mgh.harvard.edu/pipermail/mne\_analysis/attachments/20200531/33d062e0/attachment.html](http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20200531/33d062e0/attachment.html) ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [June 1, 2020, 7:37am UTC](https://mne.discourse.group/t/mne-epochs-response-events-disappear-when-locking-on-stimulus-events/2207/2 "2020-06-01T07:37:53Z")
External Email - Use Caution Dear Mat, to keep the stim channel in the Epochs you need to pass the picks parameter making sure it contains the stim channel in the list. To repochs it's no so easy right now. You would need to start from raw again. Or you can make it work using EpochsArraw dealing with numpy directly. Given how many times this question as been asked I feel we need an example on the MNE website for this usecase. We would need first a good public dataset to demo this. Alex ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [June 1, 2020, 9:06am UTC](https://mne.discourse.group/t/mne-epochs-response-events-disappear-when-locking-on-stimulus-events/2207/3 "2020-06-01T09:06:27Z")
External Email - Use Caution Hi Alex, Thanks for the help. I tried passing the stim channel using: epochs = mne.Epochs(raw\_EEG\_av\_ref\_filt, raw\_events, event\_stim\_dict, tmin=-0.2, tmax=1.8, baseline=(-.2, 0), preload=True, picks = ['eeg','eog','stim']) However, epochs.events still only contains locking events (removing response triggers) Am I doing something wrong? Mat ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [June 1, 2020, 7:58pm UTC](https://mne.discourse.group/t/mne-epochs-response-events-disappear-when-locking-on-stimulus-events/2207/4 "2020-06-01T19:58:43Z")
External Email - Use Caution you're doing nothing wrong. It won't be in events but you will have the stim channel in the epochs.get\_data() so technically you can find the onset of the response and do what you want via an EpochsArray. But I agree it's far from trivial. Sorry but I don't a better solution to offer. Maybe someone here can suggest something If I have access to data with this I can try to make an example Alex