fMRI Journal Club

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fMRI Journal Club 18 December 2006
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Overview

• Goal Can relatively small (lt 1 mm) movements
  create regions of false activation?

• How Design a controlled system capable of
  creating in-plane translations (0.74 mm) and
  rotations (0.47) with 0.31 lt r lt 0.96.

• Findings In-plane movements 1 mm create
  regions of false activation if they are
  correlated (r gt 0.67) with a blocked stimulus
  paradigm.

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What does r look like?
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The fancy phantom
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Pneumatic system validation

• In-plane translation 0.74 0.36 mm
• Through-plane trans. 0.01 0.08 mm
• Rotations x (pitch) 0.24º 0.05º
• y (roll) 0.02º 0.06º
• z (yaw) 0.47º 0.42º

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Results - total cluster size

• Exclusion criteria - at phantom edges
• - regions lt 10 voxels or gt 300 voxels

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Results - of clusters
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Results - false activation

• r 0.52

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Results - in vivo data

• Human volunteers (4) are subjectedto passive,
  in-plane head motion.
• In-plane translation lt 2 mm
• Through-plane trans. lt 0.2 mm
• In-plan rotations lt 0.5º
• Through-plane rotations lt 0.3º
• Activation observed in one subject using the
  more stringent threshold.
• Activation in the left parietal cortex.
• Is this motion-induced false activation?

r 0.75
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Questions?