Hi - do you mean differences in scaling across nodes, or within-node differences across subjects? Cheers.
> On 25 Oct 2018, at 09:21, David Hofmann <davidhofma...@gmail.com> wrote: > > Thanks for the reply Stephen, > > do you have an idea, how these different amplitudes arise? Do they just > reflect the strength of the BOLD fluctuations within these regions/components > or are they also influenced by other factors like noise or something? I'm > trying to understand if such differences do not arise purely to noise or are > artifacts of some sort and have some physiological meaning. > > greetings > > David > > Am Do., 25. Okt. 2018 um 09:03 Uhr schrieb Steve Smith <st...@fmrib.ox.ac.uk > <mailto:st...@fmrib.ox.ac.uk>>: > Hi - > > In the most recent PTN release, all node maps (melodic_IC.dtseries.nii) > created with group-ICA are sign-flipped (if necessary) to have positive > maximum voxel/greyordinate, and then rescaled so this peak is 1. The values > of other voxels across the map will vary from node to node, and the overall > map determines the scaling of the node timeseries. So yes different nodes > can have different amplitudes, but the scaling (for any given node) is > consistent across subjects. > > btw it looks like the actual stddev of those two timeseries are not massively > different. > > Cheers. > > > > > On 24 Oct 2018, at 23:46, David Hofmann <davidhofma...@gmail.com > > <mailto:davidhofma...@gmail.com>> wrote: > > > > Hi all, > > > > I was taking a look at the ICA (100) node time series and noticed that some > > ROIs have relatively large magnitude while others have a smaller magnitude > > (see attached pictures). Can someone explain to me how these differences > > arise? In other words, is this the "natural" BOLD activity within the ROI > > or does it somehow come about through the ICA and does not have any meaning? > > > > Thanks in advance, > > > > David > > _______________________________________________ > > HCP-Users mailing list > > HCP-Users@humanconnectome.org <mailto:HCP-Users@humanconnectome.org> > > http://lists.humanconnectome.org/mailman/listinfo/hcp-users > > <http://lists.humanconnectome.org/mailman/listinfo/hcp-users> > > > > <ROI2.jpg><ROI1.jpg> > > > --------------------------------------------------------------------------- > Stephen M. Smith, Professor of Biomedical Engineering > Head of Analysis, WIN (FMRIB) Oxford > > FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK > +44 (0) 1865 610470 > st...@fmrib.ox.ac.uk <mailto:st...@fmrib.ox.ac.uk> > http://www.fmrib.ox.ac.uk/~steve <http://www.fmrib.ox.ac.uk/~steve> > --------------------------------------------------------------------------- > > Stop the cultural destruction of Tibet > > > > > > > > > --------------------------------------------------------------------------- Stephen M. Smith, Professor of Biomedical Engineering Head of Analysis, WIN (FMRIB) Oxford FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK +44 (0) 1865 610470 st...@fmrib.ox.ac.uk http://www.fmrib.ox.ac.uk/~steve <http://www.fmrib.ox.ac.uk/~steve> --------------------------------------------------------------------------- Stop the cultural destruction of Tibet <http://smithinks.net/> _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users
