Functional organization of activation patterns in children: whole brain fMRI imaging during three different cognitive tasks

Abstract

1. Patterns of brain activation were measured with whole brain echo-planar functional magnetic resonance imaging (fMRI) at 3.0 Tesla in healthy children (N = 6) and in one child with a left-hemisphere encephalomalacic lesion as sequellae from early stroke. 2. Three cognitive tasks were used: auditory sentence comprehension, verb generation to line drawings, and mental rotation of alphanumeric stimuli. 3. There was evidence for significant bilateral activation in all three cognitive tasks for the healthy children. Their patterns of activation were consistent with previous functional imaging studies with adults. 4. The child with a left-hemisphere stroke showed evidence of homologous organization in the non-damaged hemisphere.

Fig 1.

Nine regions of interest (Brodmann’s areas in parentheses): F1 - superior frontal (6, 8); F2 - prefrontal (9, 10); F3 - inferior frontal (44, 45, 46, 47); T1 - superior temporal (21, 22); T2 - inferior temporal (20, 37); O - occipital (17, 18, 19); P1 - inferior parietal (39, 40); P2 - superior parietal (7); C - cingulate (30, 31, 32). The 21 acquisition slices covered most of the brain except for the superior portion of the central sulcus and the inferior portion of the temporal lobe (including inferior portion of Brodmann’s Area 20, 36, and 38). The inferior portions of the temporal lobes were not scanned due to image artifacts created by the orbits and nasal cavities (from Sundsten, 1994).

Fig 2.

Percentage of total voxels activated in each region of interest for the three cognitive paradigms. Data in first row represent healthy children (N=6). Data in second row represent child a with stroke (SJ). Black bars represent right hemisphere and open bars represent left hemisphere. Regions of interest are represented on the x-axis. Error bars indicate one standard error for the healthy children.

Figure 3.

Functional activation superimposed on high-resolution structural images. Black squares indicate significant activation (t > 5.0) in the experimental paradigm compared to resting level fixation. Data in first row represent mean for healthy children (N=6). Data in second row represent the child with a stroke (S.J). Slice for sentence processing task is through superior temporal gyrus, slice for verb generation task is through visual association area, and slice for mental rotation task is through superior parietal area. The high resolution structural image for the healthy children is from a representative child. Note that the darker gray in the panels for SJ illustrate the extent of his lesion.