[FieldTrip] auditory evoked gamma

[Robert Oostenveld]

Hi Nenad

On 7 Mar 2013, at 7:08, Nenad Polomac wrote:
> I would like to ask you for a suggestion about localisation o auditory evoked gamma osculations. I checked all tutorials and I haven't found much help. DICS beamformer doesn't work in this case. 


Please do note that the tutorials are not meant as a complete list of analyses that you can do, but they merely provide a practical starting point. Something not being listed on the fieldtrip wiki does not mean that it cannot be done. 

One would not expect strong correlations/coherence between auditory activity in the gamma band, so beamforming is from a methodological viewpoint also not as problematic for high frequenies as it is for AEFs. This paper by Till Schneider (http://www.ncbi.nlm.nih.gov/pubmed/18617422) demonstrates that with EEG beamforming of auditory gamma is possible. 

If you fear for too strong correlations, you can try subsets of channels over both hemispheres. Or use a symmetric dipole pair (cfg.symmetric in ft_prepare_leadfield) as source model.

best regards,
Robert