# Head Motion Estimate¶

Head motion has been found having an impact on rs-fMRI signals. In preprocessing, six head motion parameters of (x-,y-,z-) translations and (pitch-,yaw-,roll-) rotations estimated during realignment are used as the inputs of the current function. By the default, the current function outputs the maximum absolute translation and rotation between frames as the exclusion criterion of large-motion subject. Additionally, the mean head displacement (the root-mean-square of translation parameters), the maximum head displacement, the number of micro displacement (>0.1mm), the mean absolute Euler angle of rotation, the framewise displacement (FD) and the number of frames with FD>0.5mm, are also exported to provide more subject exclusion criteria.

• id index: identifier to find unique string for each subject
• filetype: files in the filetype will be searched in input directories.
• input dirs: directories can be input either using a .txt file or spm select window.
• out dir: output directory for saving results.
• Meaning of results:
• max-abstranslation(mm): maximum translation. Estimated as the max absolute value of the first 3 columns from rp*.txt
• max-absrotation(deg): maximum rotation. Estimated as the max absolute value of the last 3 columns from rp*.txt multiple by 180/pi.
• From van Dijk et al., Neuroimage 2012
• max-motion-Dijk(mm): maximum root-mean-square of translation.
• mean-motion-Dijk(mm): mean root-mean-square of translation.
• num-movements-Dijk(>0.1mm): number of micro-movement. The number of root-mean-square of translation that is greater than 0.1mm
• mean-rotation-Dijk(deg): mean absolute Euler angle
• From Power et al., Neuroimage 2012
• mean-FD(mm): frame-wise displacement. Estimated using translation and rotation.
• num-FD>0.5: number of frame-wise displacement that is greater than 0.5mm.
• Buttons:
• S: Save parameters of the current panel to a *.mat file. The *.mat can be further loaded for the panel or be used in a script processing.
• L: Load parameters from *.mat for the current panel.
• ?: Help information.
• References:
1. Van Dijk KR, Sabuncu MR, Buckner RL. The influence of head motion on intrinsic functional connectivity MRI. Neuroimage 2012; 59(1): 431-8.
2. Power JD, Barnes KA, Snyder AZ, Schlaggar BL, Petersen SE. Spurious but systematic correlations in functional connectivity MRI networks arise from subject motion. Neuroimage 2012; 59(3): 2142-54.