Search found 9 matches

by Douwehorsthuis
Wed Jun 09, 2021 2:35 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 11
Views: 17420

Re: Strange activity on a single electrode

I know BioSemi suggests re-referencing the data (https://www.biosemi.com/faq/cms&drl.htm). Would it matter if this re-referencing happens at the beginning or later in the pre-processing pipeline? (EEGlab allows you to directly apply references to your data when you start working with a raw BDF file)...
by Douwehorsthuis
Mon Jan 11, 2021 9:09 pm
Forum: BioSemi Hardware
Topic: Post hoc measurement of EEG quality
Replies: 3
Views: 2685

Re: Post hoc measurement of EEG quality

Thanks for the offset info, but it's unfortunately not entirely clear how to see this when importing this data in matlab (EEGLAB). Am I correct to say that it is (the amplitude for each sample point) - (the average of 20sec of data)? Besides offsets, are there other ways of saying anything about the...
by Douwehorsthuis
Thu Jan 07, 2021 5:58 pm
Forum: BioSemi Hardware
Topic: Post hoc measurement of EEG quality
Replies: 3
Views: 2685

Post hoc measurement of EEG quality

Good morning, I was wondering if there is some sort of way to say anything about the quality of EEG data after a recording is done. I can come up with simple ways like: 1) amount of channels that have too much high frequency noise 2) channels that have too much drift 3) channels that have are flat B...
by Douwehorsthuis
Fri Aug 28, 2020 3:59 pm
Forum: BioSemi Hardware
Topic: EEG with black people's hair in mind
Replies: 4
Views: 4637

Re: EEG with black people's hair in mind

Dear Mary Woody, Thank you for replying and being vocal about this issue. I think the thought of irrelevance for the need for change or solutions stems in part from the lack of sound from people that problem solve on their own instead of as a group. I have seen the preprint before and even though it...
by Douwehorsthuis
Fri Aug 28, 2020 3:31 pm
Forum: BioSemi Hardware
Topic: EEG with black people's hair in mind
Replies: 4
Views: 4637

Re: EEG with black people's hair in mind

The suggestion of using smaller electrode channels is not new. Indeed, it seems to be the solution BioSemi agreed to put forward as the working solution. Though I am confident that this solution is science-based and that you have tested this in different hair types, I am left wondering how this real...
by Douwehorsthuis
Wed Jun 24, 2020 4:50 pm
Forum: BioSemi Hardware
Topic: EEG with black people's hair in mind
Replies: 4
Views: 4637

EEG with black people's hair in mind

Good morning, I wanted to describe an issue we run into but for that I need to give some context : It seems like EEG equipment was made using either mainly or only white people as a model. This potentially results in difficulties when we try to collect data from black people. We are in a unique and ...
by Douwehorsthuis
Tue Sep 18, 2018 7:19 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 11
Views: 17420

Re: Strange activity on a single electrode

Is it possible that when we reference (lets say to the mastoids) in MATLAB we add this information to those flat channels? after this maybe the channels do not look flat anymore, but contain mastoid information that shouldn't be there?
by Douwehorsthuis
Sat Sep 08, 2018 2:46 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 11
Views: 17420

Re: Strange activity on a single electrode

That is very interesting. Would you have an idea why matlab (or EEG lab) would not exclude these channels all the time then?
Thanks again,
Douwe
by Douwehorsthuis
Thu Sep 06, 2018 4:01 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 11
Views: 17420

Re: Strange activity on a single electrode

Hi, I was wondering how problematic this issue is. It happens to us for a decent amount of participants, yet when I look at the preproccesed data, I see that both P2 and P1 are almost never excluded. Does this mean that when we look at the data during the data collection and see these noisy/flat cha...