Introduction: Action of the ascending reticular activating system (ARAS) on the cerebral cortex is responsible for achievement of consciousness. In this study, we attempted to reconstruct the lower single component of the ARAS from the reticular formation (RF) to the thalamus in the normal human brain using diffusion tensor imaging (DTI). Methods: Twenty six normal healthy subjects were recruited for this study. A 1.5-T scanner was used for scanning of diffusion tensor images, and the lower single component of the ARAS was reconstructed using FMRIB software. We utilized two ROIs for reconstruction of the lower single component of the ARAS: the seed ROI - the RF of the pons at the level of the trigeminal nerve entry zone, the target ROI - the intralaminar nuclei of the thalamus at the level of the commissural plane. Results: The reconstructed ARAS originated from the pontine RF, ascended through the mesencephalic tegmentum just posterior to the red nucleus, and then terminated on the intralaminar nuclei of the thalamus. No significant differences in fractional anisotropy, mean diffusivity, and tract number were observed between hemispheres (P>0.05) Conclusion: We reconstructed the lower single component of the ARAS from the RF to the thalamus in the human brain using DTI. The results of this study might be of value for the diagnosis and prognosis of patients with impaired consciousness

We investigated the effect of task-oriented training (TT) on the cortical activation pattern in four chronic hemiparetic stroke patients. A TT program, consisting of six tasks, which were designed to improve hemiparetic upper extremity function, was performed for 40 min/day, 4 days/week for 4 weeks. The functional status of the affected hand and fMRI were assessed before and after the TT program. fMRI was performed at 1.5 T in parallel with timed finger flexion–extension exercises at a fixed rate. The main cortical activation changes with functional recovery were a decrease in the unaffected and an increase in the affected primary sensorimotor cortex activities. In conclusion, it seems that cortical reorganization was induced by the TT program in chronic hemiparetic stroke patients.

BACKGROUND AND PURPOSE: Little is known about differences in corticospinal tract fibers according to cerebral origin. Using diffusion tensor tractography, we attempted to investigate the characteristics of the CST according to the cerebral origin in the human brain. MATERIALS AND METHODS: Thirty-six healthy subjects were recruited for this study. A 1.5T Gyroscan Intera system was used for acquisition of DTI. CSTs were reconstructed by selection of fibers passing through seed and target ROIs: seed ROIs, the area of the CST at the pontomedullary junction; target ROIs, the primary motor cortex, the primary somatosensory cortex, the dorsal premotor cortex, and the supplementary motor area. RESULTS: A significant difference in tract volume was observed in each ROI (P < .05): M1 (2373.6, 36.9%), S1 (2037.7, 31.7%), SMA (1588.0, 24.7%), and dPMC (429.8, 6.7%). Regarding fractional anisotropy values, the dPMC or SMA showed higher values than the M1 or S1; however, the opposite occurred in terms of the mean diffusivity value (P < .05). In addition, fractional anisotropy and mean diffusivity values of the dPMC differed from those of the SMA (P < .05); in contrast, no significant difference was observed between the M1 and S1 (P > .05). CONCLUSIONS: Tract volume was found to differ according to cerebral origin and was, in descending order, M1, S1, SMA, and dPMC. In addition, the directionality and diffusivity of CST fibers in the SMA and the dPMC differed from those of the M1 and S1, which showed similar characteristics.

We reviewed the literature on walking recovery of stroke patients as it relates to the following subjects: epidemiology of walking dysfunction, recovery course of walking, and recovery mechanism of walking (neural control of normal walking, the evaluation methods for leg motor function, and motor recovery mechanism of leg). The recovery of walking is one of the primary goals in stroke patients, along with the recovery of hand function and cognition. Walking function has greater potential for recovery than hand function because motor function of the leg is less dependent on the lateral corticospinal tract than that of hand function. This suggests that detailed knowledge of walking can be used to increase the likelihood that stroke patients recover their ability to walk. Therefore, we suggest that further research should focus on these topics, especially, on the neural control mechanism of walking and motor recovery mechanisms of the leg in stroke patients.

BACKGROUND AND PURPOSE: The AF is an important neural tract in language function. We investigated aphasia outcome according to DTT findings for AF in the early stage of stroke. MATERIALS AND METHODS: Twenty-five consecutive patients with aphasia and stroke and 12 control subjects were recruited. The AQ of K-WAB was used for the assessment of aphasia in the early stage of stroke (10–30 days) and at approximately 6 months after onset. We classified the patients into 3 groups according to the severity of left AF injury: type A, the AF was not reconstructed; type B, the AF was disrupted; and type C, the AF was preserved around the lesion. RESULTS: When comparing AQ among AF types at early evaluation, the type C score (32.84 ± 18.05) was significantly higher than type A (3.60 ± 2.73) (P < .05). However, no significant difference was observed between types A and B (18.02 ± 17.19) or between types B and C (P > .05). At late evaluation, the AQ values of types B (52.43 ± 25.75) and C (68.08 ± 15.76) were higher than that of type A (10.98 ± 3.90) (P < .05). However, there was no significant difference between types B and C. CONCLUSIONS: The aphasia outcome of the patients whose left AF could be reconstructed was better than that in patients whose left AF could not be reconstructed, irrespective of its integrity. We believe that evaluation of the left AF by using DTT in the early stage of stroke could be helpful in predicting aphasia outcome in patients with stroke.