Source coherence

[Robert Oostenveld]

Hi Masao,

On 25 May 2005, at 23:35, Matsuhashi, Masao (NIH/NINDS) wrote:

> As regards the low-occipital low frequency noise, I thought that as
> long as
> such activity was not correlated with the reference signal it would not
> affect the coherence analysis very much (only that it might lower the
> coherence value in some channels). How do you think it will affect the
> source coherence?

If present in the spatial structure of the cross-spectral density
matrix, it affects the spatial filters. And hence it will affect the
estimate of the source cross-spectral density. Since coherence is
source CSD normalised by power, ideally it would not affect the source
coherence. But I still would not be too confident about it, since the
influence of artifacts on the filter can be difficult to predict.

Robert