Hi The actual group-ICA maps are not thresholded - but yes there is a preset colour overlay threshold applied by default in the papaya viewer.
For the latest (~1000 subjects) PTN release, the volumetric maps were created within-subject using dual-regression, and are z-stat maps from the second-stage of the dual regression. Strictly, for each 15min run they are tstats, but the temporal DOF is so high that it's not much of a distinction between that and Z. They are then treated as Z when combining across the 4 runs, and again when averaging across all subjects. So in theory the final Z maps should follow Z distribution (up to an overall N-dependent scaling factor), but there is so much "signal" around from this many subjects that it's a little hard to test the null for its exact width. Cheers, Steve. > On 29 Sep 2017, at 18:54, Jenny Gilbert <jennyrg...@gmail.com> wrote: > > Quick question about the papaya viewer interface associated with the > Group-ICA parcellation used in megatrawl: is the activation threshold > (default is set to 10 to 40) used t-value or z-value? > > Thanks, > Jenny Gilbert > > _______________________________________________ > HCP-Users mailing list > HCP-Users@humanconnectome.org > http://lists.humanconnectome.org/mailman/listinfo/hcp-users > --------------------------------------------------------------------------- Stephen M. Smith, Professor of Biomedical Engineering Head of Analysis, Oxford University FMRIB Centre FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK +44 (0) 1865 222726 (fax 222717) 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
