ARTIFACT DETECTION AND REMOVAL IN FMRI TIMESERIES DATA PDF
Preview ARTIFACT DETECTION AND REMOVAL IN FMRI TIMESERIES DATA
ARTIFACT DETECTION AND REMOVAL IN FMRI TIMESERIES DATA The insidious consequences of head mo=on Deen & Pelphrey (2012) Nature Func=onal connec=vity and brain matura=on Fair et al. (2009) PLoS Computa/onal Biology; Dosenbach et al. (2010) Science Decoding brain age from connec=vity “The paGern of fcMVPA feature weights indicated that func=onal matura=on is driven both by the segrega=on of nearby func=onal areas, through the weakening of short-‐range funcBonal connecBons, and the integra=on of distant regions into func=onal networks, by strengthening of long-‐range funcBonal connecBons” Dosenbach et al. (2010) Science Decoding brain age from connec=vity Model accounts for 55% of variance in age! “The paGern of fcMVPA feature weights indicated that func=onal matura=on is driven both by the segrega=on of nearby func=onal areas, through the weakening of short-‐range funcBonal connecBons, and the integra=on of distant regions into func=onal networks, by strengthening of long-‐range funcBonal connecBons” Dosenbach et al. (2010) Science Could this phenomenon be (at least par=ally) driven by an ar=fact? This matura=on paGern largely disappears once head mo=on is ¨ taken into account. Some quotes from lead inves=gator Steve Petersen: ¨ “It really, really, really sucks. My favorite result of the last five ¨ years is an arBfact” “Let me tell you, denial was big. We had every explanaBon in ¨ the world other than that it was an arBfact. But it’s an arBfact.” “The insidious part of this is, it’s Bny liTle movements that most ¨ people, including us previously, completely ignore.” hGp://sfari.org/news-‐and-‐opinion/news/2012/movement-‐during-‐brain-‐scans-‐may-‐lead-‐to-‐spurious-‐paGerns The Problem: Mo=on effects are not equally distributed throughout the brain Displacement is maximal at voxels that are far from the pivot around which rotaBon occurs Not surprisingly, moBon regressors explain the most signal variance in these high moBon regions. Long-‐range func=onal connec=vity is diminished in wiggly subjects Van Dijk, Sabuncu, & Buckner (2012) NeuroImage And short-‐range func=onal connec=vity can be augmented in wiggly subjects Van Dijk, Sabuncu, & Buckner (2012) NeuroImage What if we take 100’s of subjects and arbitrarily divide them into groups based on their mean mo=on? ² Default Mode Network connec=vity (PCC seed) is reduced in subject groups with more mo=on, even when differences are miniscule (0.044mm vs. 0.048mm mean mo=on) Van Dijk, Sabuncu, & Buckner (2012) NeuroImage
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