Whole-brain Functional MR Imaging Activation from a Finger-tapping Task Examined with Independent Component Analysis
Chad H. Moritz
,a,
Victor M. Haughtona,
Dietmar Cordesa,
Michelle Quigleya and
M. Elizabeth Meyeranda
a From the Departments of Radiology (C.H.M., V.M.H.) and Medical Physics (D.C., M.Q., M.E.M.), University of Wisconsin, Madison, WI.
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FIG 1. fMR imaging map processed with ICA in one subject who performed bilateral finger tapping. Activation is shown in the left sensorimotor cortex, SMA, thalamus, putamen, superior sylvian region, and right superior cerebellum. The component illustrated correlated temporally with a reference function for right-hand finger tapping (Note: all figures are radiologic orientation).
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FIG 2. fMR imaging spatial map processed with ICA, in the same subject as in figure 1, illustrating another component. Activation is shown in the right sensorimotor cortex, SMA, thalamus, putamen, superior sylvian region, and left superior cerebellum. This component had a high correlation coefficient with a reference function for left-hand finger tapping
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FIG 3. Relative signal-versus-time plots for sample ICA components from the data sets of subjects who performed cycles of rest, right-, and left-hand finger tapping. Lower dashed lines indicate task timing. One component labeled "right hand" has greatest relative signal during the right-hand task performance One component, labeled "left hand," shows maximal increase during left-hand finger tapping and a reduced increase during right-hand finger tapping. Note the components plateau about 5 seconds after the initiation of the task.
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FIG 4. ICA components in subjects performing the left- and right-finger tapping task, with unequal lengths of epochs. Rest and finger-tapping cycles varied in length from 16 to 24 seconds. Lower dashed lines indicate task timing. The components correlate closely with the expected hemodynamic response for each hand task
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FIG 5. A, Another ICA component that was identified in the data set of subjects performing the alternating finger-tapping task. This component correlates temporally with the delivery of auditory instructions to the subject to initiate or terminate a task. Such a component was found in each of the subjects.
B, The component is superimposed on the components correlating with right- and left-hand finger movement. Lower dashed lines indicate task timing. Note that the fluctuations in the component correspond to the initiation and termination of the motor tasks.
C, fMR image of the independent component illustrates activation localized to the auditory cortices.
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FIG 6. A, Representative three-axis map of an ICA component specific to bilateral putamen. Similar component maps were identified in three subjects. Spatial localization is specific to the anterior putamen bilaterally and to no other regions.
B, Signal-versus-time plots of this ICA component overlaid on the components for left- and right-hand finger tapping. Note that the component increases as the subject initiates the left- or right-hand tasks. Lower dashed lines indicate task timing.
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