FIG. 1.

Deficits in injury-ipsilateral forelimb circuitry are revealed by affected forelimb-evoked brain activation by blood oxygenation level–dependent (BOLD) functional magnetic resonance imaging (fMRI). (A) Group mean, affected (right) forelimb–evoked activation data (one-tailed t-test, corrected for multiple comparisons, p < 0.001, z > 1.7) before and at 1, 2, 3, and 4 weeks after injury, superimposed on a rat brain template as coronal image plots and surface-warped data. Plots of (B) number of significantly activated voxels in the right M1 and S1-forelimb cortex contralateral to the stimulated limb (ipsilateral to the injury site) and (C) number of activated voxels in the cortex ipsilateral to the stimulated limb (contralateral to the injury site). Data show widespread injury-ipsilateral inactivation after injury (A) that was significant for time in the injury-ipsilateral (left) M1/S1-florelimb cortex (C, p < 0.001) and specifically at 3–4 weeks post-injury (C, *p < 0.05). Data also show that there were early diffuse activated regions contralateral to the injury, ipsilateral to the stimulated limb (A) that was variable between rats because the mean effect was not significant for the number of activated voxels in contralateral (right) M1/S1-forelimb cortex (B). Key: Hatched circle represents approximate position of primary injured region.