SSVEP parameters & CSP

[Aravind]

Hi all,
I am an undergraduate student trying to use OpenViBE with an OpenBCI system for BCI applications. Firstly, I would like to thank the OpenViBE team for this amazing tool for EEG analysis and the driver support for OpenBCI. Currently my team and I are trying to use the ssvep paradigm for our project. We have been trying to understand the ssvep scenarios of OpenVibe. Some of the doubts and queries are:

1. Is there a reference paper that uses CSP as a feature extraction technique? We have been reading some papers where CSP is not used. I request you to kindly clarify on the reference.
2. When trying to use the configuration scenario, we are able to modify the flickering frequency, color settings, and target stimulations but we are not able to change the size of the target and position of the target.

These are some of the clarifications we need. I request someone to please help us in this regard.




Thanks
Regards
Aravind

[jtlindgren]

Hi Aravind,

1. I think the SSVEP work is based on publications of the contributor who made the demos, you can find more details from the following paper, and following the links there,

http://ieeexplore.ieee.org/xpl/articleD ... er=6509428

2. I imagine that in order to modify the parameters you mention, you may need to modify the corresponding C++ code and recompile. You can find these in applications/demos/ssvep-*.


Cheers,
Jussi

[Aravind]

Hi Jussi,

Thank You for the IEEE reference, I think this will give us more clarity in understanding the OpenViBE scenarios, and VR application. I will look into the C++ code and try to modify it, and get back.
In some of the other references for SSVEP, there is no mention of CSP, also there have been good results with 1-3 electrodes/channels (Ex:O1,O2,Oz). Currently, we are running our tests and experiments with the existing scenarios. So, some of the questions that we are trying to address are:
Does implementing with more channels and using CSP give better performance of an SSVEP based BCI? compared to using a reduced set of channels with the same band-power features?


Regards
Aravind

[avv]

Hi Aravind,

I am also an undergraduate using the same OpenVibe ssvep paradigm with an OpenBCI system. So far we have not reached successful online application. Were you able to successfully play the game with the OpenBCI system?

Best,
Angela

[Aravind]

Hi Angela,

Yes, we were able to play the online game with the OpenBCI system. We followed the same electrode positions as per the given scenario, we changed the flicker frequencies to 10Hz, 12Hz, and 15Hz. Apart from this, under the classifier trainer we used LDA with one vs all strategy. According to the literature on ssvep, some frequencies are more responsive than others for a particular person. So, you will have to experiment on this aspect and find out these frequencies.
If you run the training scenarios and CSP scenarios in the given order, I think it should work!

Hope this was helpful. All the best!


Regards,
Aravind R