Re: [HCP-Users] parcellation papaya viewer

[Stephen Smith]

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  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
> 
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> HCP-Users mailing list
> HCP-Users@humanconnectome.org
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---
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.ukhttp://www.fmrib.ox.ac.uk/~steve 

---

Stop the cultural destruction of Tibet 






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[HCP-Users] parcellation papaya viewer

[Jenny Gilbert]

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

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