Frequency selection for SSVEP

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altafadil786
Posts: 1
Joined: 19 Nov 2010, 11:50

Frequency selection for SSVEP

Post by altafadil786 » 13 Feb 2011, 15:12

For a monitor with refresh rate of 60Hz, what would be the best frequency set for efficiently detecting SSVEP response?

I need to select 4 frequencies for the flickering checkerboard so that four directions can be controlled for cursor movement.

Thanks

jawilson
Posts: 109
Joined: 28 Feb 2005, 16:31

Post by jawilson » 15 Feb 2011, 21:14

Hello,
I am not really an expert on SSVEP, but I am not aware that you can do it very well with a monitor. Typically, it is done with an external LED box, where the flash rate of the LEDs can be specified very precisely. With a monitor, you are very limited by 1) the refresh rate, 2) the on/off time of the pixels, and 3) the fact that BCI2000 is not synchronized with the refresh rate of the monitor. If you HAD to use a monitor, the flashing rates would probably need to be divisors of 60 hz, e.g., 5, 6, 10, 12, 15, 20, etc, and you would need to adapt BCI2000 to sync with the monitor refresh. I would recommend, though, using an external system, which doesn't need to be synced with BCI2000 at all.

I could also be wrong about this :-). Hopefully someone else can confirm or expand on what I wrote.
Adam

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