Animation of a Functional MRI Study

Error Detection and Correction in Motor Function

Jutta Ellermann, John Strupp, Kamil Ugurbil

The animation is a rendered Functional Magnetic Resonance Imaging fMRI data set that was created for the Power Wall at the Laboratory for Computational Science and Engineering (LCSE).

Shown is a rotating human head with associated brain activation from a subject performing a task that utilizes motor, visual and planning cognitive processes.

The rendering was done by John Strupp with data provided by Jutta Ellermann. This work was done at the Center for Magnetic Resonance Research (CMRR) of the University of Minnesota Medical School and was supported in part by NIH Grant RR08079.

Rendering software used was "VoxelView 2.5" from Vital Images, Inc.

The movie shows human brain activation associated with performance of a task that utilizes motor, visual and planning cognitive processes. The head of the subject is first rendered as an opaque volume, followed by the skull changing from translucent to transparent in order to show the activation on the cerebral cortex.

Activation within the deeper structures of the brain are shown by panning through, in turn, each of the three orthogonal planar views.

Axial Coronal Sagittal

By use of a translucent opacity for the brain, while maintaining the activation as opaque, the three dimensional structure of the activation is illustrated.

Then from a posterior view, the cerebrum fades out to leave only the cerebellum.

The cerebellum is then replicated into two cerebellums but is still from the same subject. The difference between the two is that the cerebellum on the left shows substantial activation caused by the subject performing a complex mental task involving planning. The cerebellum on the right shows only minimal activation due to the the subject performing a relatively simple task. The pair of cerebellums then turn translucent to allow the underlying opaque activation to be shown.

All About Functional Magnetic Resonance Imaging (FMRI)

Funtional Magnetic Resonance Imaging is a technique that exploits a phenomenon known as the BOLD effect Ogawa et.al. to identify regions of the brain that are involved in performing specific tasks. For example, some early work was done with finger movement and visual cortex experiments. In these experiments a volunteer in the magnet was instructed to repeatedly touch their fingers to each other during certain periods of time. In the case of visual cortex experiments, volunters wore glasses with led's attached to them in the magnet, and the led's were flashed during certain portions of an imaging sequence. By looking for differences of intensity between task periods and relaxation periods, it was possible to identify areas of the brain that were stimulated by these tasks. The Center for Magnetic Resonance Research was the site for much of the original FMRI work. Research and development of FMRI techniques continues to be a large part of the Research effort at the Center.

FMRI Results

Figure1 (courtesy of Dr Seong-Gi Kim)
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A functional map (in color) in the cerebellum during performance of a cognitive peg-board puzzle task, overlaid on a T2*-weighted axial image in gray scale. The dentate nuclei appear as dark crescent shapes at the middle of the cerebellum due to iron deposits. fMRI images were acquired by conventional T2*-weighted FLASH techniques with a spatial resolution of 1.25x1.25x8 mm3 and a temporal resolution of 8 seconds. Each color represents a 1% increment, starting at 1%. R, right cerebellum; L, left cerebellum. A left-handed subject used the left hand to perform the task. Bilateral activation in the dentate nuclei and cerebellar cortex was observed. The activated area in the dentate nuclei during performance of pegboard puzzle was 3-4 times greater than that seen during the visually guided peg movements. (see details in Kim et al., 1994b).

Figure2 (courtesy of Dr Kamil Ugurbil)
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Whole brain functional imaging study during a visuo-motor error detection and correction task. Functional images were acquired by the multi-slice single-shot EPI imaging technique with spatial resolution of 3.1x3.1x5 and temporal resolution of 3.5 seconds. The skull and associated muscles were eliminated by image segmentation. The 3-D image constructed from multi-slice images was rendered by Voxel View program (Vital Images, Fairfield, Iowa).The task was to move a cursor from the central start box onto a square target by moving a joystick. Eight targets were arranged circumferentially at 45! angles and displaced radially at 20! around a central start box. Activation (in color) is observed at various brain areas. Top image displays the brain as a 3-D solid object so that only the cortical surface is seen. In the bottom image, a posterior section was removed at the level of the associative visual cortex to display activation not visible from the surface (Kindly provided by Jutta Ellermann, Jeol Seagal, and Timothy Ebner).

Figure3 (courtesy of Dr Seong-Gi Kim)
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A BOLD-based functional map during right finger and right toe movements, combined with head sketch. Since an oblique slice was selected along the left central sulcus, the left hemisphere is shown predominantly. An arrow indicates the left central sulcus. Yellow represents functional areas activated only during the finger movements; red, only during the toe movements; and green, during both tasks. (Kim et al., 1994a).