Hi Georgios and Francesco Thanks for your help and the script! My doubts are solved.
Cheers, Adoney On Mon, Nov 20, 2017 at 10:22 AM, Georgios Michalareas <g...@ae.mpg.de> wrote: > Hi Adoney (and Francesco), > > Francesco is right. The ICA was done independently per session. But this > should not cause a problem to your analysis if you are using the > preprocessed resting state data i.e. > > 177746_MEG_3-Restin_rmegpreproc.mat > > 177746_MEG_4-Restin_rmegpreproc.mat > > 177746_MEG_5-Restin_rmegpreproc.mat > Because in these files only the independent components corresponding to > eye movements and heart artifacts have been removed. This artifacts have > quite standard topology, quite similar across the different scans. > So under the assumption that there are small head movements between scans > , if you concatanate the datasets and then you do ICA then you should be > able to capture the same brain Independent components across all three > scans. The effect of the removed eye and heart artifacts from each scan > separately on the ICA on the concatenated data should be negligible as long > as the head movement is small. > > I hope this helps > Best > Giorgos > > > On 11/20/2017 2:09 PM, Francesco Di Pompeo wrote: > > Hi, > > > > ICA has been performed on the three sessions separately so I think it’s > better to use a different strategy. > > > > Best, > > Francesco > > > > *Da:* hcp-users-boun...@humanconnectome.org [mailto:hcp-users-bounces@ > humanconnectome.org <hcp-users-boun...@humanconnectome.org>] *Per conto > di *Michalareas, Georgios > *Inviato:* venerdì 17 novembre 2017 14:15 > *A:* A Nunes <adonay.s.nu...@gmail.com> <adonay.s.nu...@gmail.com>; > HCP-Users@humanconnectome.org > *Oggetto:* Re: [HCP-Users] MEG resting state > > > > Hi Adoney, > > The released data has been only 7.5 mm maximum movement within scan. > > So the sensor positions should be quite close in all three resting state > scans. > > ICA was done with all three sessions concatenated together. > > So I believe it should be one to concatenate them for your analysis too > and assume sensors are more or less on same location. > > If you want to treat each different scan separately then you have to > follow different strategies like: > > -Perform beamforming for each session separately and project each session > separately into source space and then concatenate data in source space and > do further analysis there. > > -Make a virtual gradiometer array as the mean of the three gradiometer > positions in the three scans and then interpolate the data of each session > to this virtual MEG sensors using Fieltrip’s function ft_megrealign and > then combine all data in this virtual sensor space. Keep in mind that this > projects the data into source space and projects it back to the virtual > sensor space. > > > > I hope this helps > > Best > > Giorgos > > > > *From: *<hcp-users-boun...@humanconnectome.org> on behalf of A Nunes < > adonay.s.nu...@gmail.com> > *Date: *Thursday, 16. November 2017 at 21:56 > *To: *"hcp-users@humanconnectome.org" <HCP-Users@humanconnectome.org> > *Subject: *[HCP-Users] MEG resting state > > > > Hi, > > > > The MEG resting state data is split in three sessions, is it possible to > append the data before computing the covariance matrix? > > I have some doubts because the sensor position might change between the > recordings and if ICA was done separately, then the rank would change > between sessions and I don't know how would this affect beamforming. > > > > Any suggestions? > > > > Thanks > > Adonay > > _______________________________________________ > HCP-Users mailing list > HCP-Users@humanconnectome.org > http://lists.humanconnectome.org/mailman/listinfo/hcp-users > > _______________________________________________ > HCP-Users mailing list > HCP-Users@humanconnectome.org > http://lists.humanconnectome.org/mailman/listinfo/hcp-users > > > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> > Virus-free. > www.avg.com > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> > <#m_-6511468309016046648_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > > > -- > ------------------------------------------------ > Dr. Georgios Michalareas > Neuroscience Department > Max Planck Institute for Empirical Aesthetics > > email: g...@aesthetics.mpg.de > phone: +49 69 8300479-325 <+49%2069%208300479325> > ------------------------------------------------ > > _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users
