Corticospinal Tract Microstructure Correlates With Beta Oscillatory Activity in the Primary Motor Cortex After Stroke

Background and Purpose: Cortical beta oscillations are reported to serve as robust measures of the integrity of the human motor system. Their alterations after stroke, such as reduced movement-related beta desynchronization in the primary motor cortex, have been repeatedly related to the level of impairment. However, there is only little data whether such measures of brain function might directly relate to structural brain changes after stroke. Methods: This multimodal study investigated 18 well-recovered patients with stroke (mean age 65 years, 12 males) by means of task-related EEG and diffusion-weighted structural MRI 3 months after stroke. Beta power at rest and movement-related beta desynchronization was assessed in 3 key motor areas of the ipsilesional hemisphere that are the primary motor cortex (M1), the ventral premotor area and the supplementary motor area. Template trajectories of corticospinal tracts (CST) originating from M1, premotor cortex, and supplementary motor area were used to quantify the microstructural state of CST subcomponents. Linear mixed-effects analyses were used to relate tract-related mean fractional anisotropy to EEG measures. Results: In the present cohort, we detected statistically significant reductions in ipsilesional CST fractional anisotropy but no alterations in EEG measures when compared with healthy controls. However, in patients with stroke, there was a significant association between both beta power at rest ( P =0.002) and movement-related beta desynchronization ( P =0.003) in M1 and fractional anisotropy of the CST specifically originating from M1. Similar structure-function relationships were neither evident for ventral premotor area and supplementary motor area, particularly with respect to their CST subcomponents originating from premotor cortex and supplementary motor area, in patients with stroke nor in controls. Conclusions: These data suggest there might be a link connecting microstructure of the CST originating from M1 pyramidal neurons and beta oscillatory activity, measures which have already been related to motor impairment in patients with stroke by previous reports.

Prediction of postoperative deficits using an improved diffusion-weighted imaging maximum a posteriori probability analysis in pediatric epilepsy surgery

OBJECTIVEThis study is aimed at improving the clinical utility of diffusion-weighted imaging maximum a posteriori probability (DWI-MAP) analysis, which has been reported to be useful for predicting postoperative motor, language, and visual field deficits in pediatric epilepsy surgery. The authors determined the additive value of a new clustering mapping method in which average direct-flip distance (ADFD) reclassifies the outliers of original DWI-MAP streamlines by referring to their minimum distances to the exemplar streamlines (i.e., medoids).METHODSThe authors studied 40 children with drug-resistant focal epilepsy (mean age 8.7 ± 4.8 years) who had undergone resection of the presumed epileptogenic zone and had five categories of postoperative deficits (i.e., hemiparesis involving the face, hand, and/or leg; dysphasia requiring speech therapy; and/or visual field cut). In pre- and postoperative images of the resected hemisphere, DWI-MAP identified a total of nine streamline pathways: C1 = face motor area, C2 = hand motor area, C3 = leg motor area, C4 = Broca’s area–Wernicke’s area, C5 = premotor area–Broca’s area, C6 = premotor area–Wernicke’s area, C7 = parietal area–Wernicke’s area, C8 = premotor area–parietal area, and C9 = occipital lobe–lateral geniculate nucleus. For each streamline of the identified pathway, the minimal ADFD to the nine exemplars corrected the pathway membership. Binary logistic regression analysis was employed to determine how accurately two fractional predictors, Δ1–9 (postoperative volume change of C1–9) and γ1–9 (preoperatively planned volume of C1–9 resected), predicted postoperative motor, language, and visual deficits.RESULTSThe addition of ADFD to DWI-MAP analysis improved the sensitivity and specificity of regression models for predicting postoperative motor, language, and visual deficits by 28% for Δ1–3 (from 0.62 to 0.79), 13% for Δ4–8 (from 0.69 to 0.78), 13% for Δ9 (from 0.77 to 0.87), 7% for γ1–3 (from 0.81 to 0.87), 1% for γ4–8 (from 0.86 to 0.87), and 24% for γ9 (from 0.75 to 0.93). Preservation of the eloquent pathways defined by preoperative DWI-MAP analysis with ADFD (up to 97% of C1–4,9) prevented postoperative motor, language, and visual deficits with sensitivity and specificity ranging from 88% to 100%.CONCLUSIONSThe present study suggests that postoperative functional outcome substantially differs according to the extent of resected white matter encompassing eloquent cortex as determined by preoperative DWI-MAP analysis. The preservation of preoperative DWI-MAP–defined pathways may be crucial to prevent postoperative deficits. The improved DWI-MAP analysis may provide a complementary noninvasive tool capable of guiding the surgical margin to minimize the risk of postoperative deficits for children.

PO-057 Motor Functional Connectivity Analysis of Brain Control Network on High Level Athletes with fMRI Research

Objective The nervous system is the control center that performs the function of the human body, including each nucleus of the cerebral cortex and basal ganglia, which can control the motion of the body through three pathways-direct pathway, indirect pathway and hyperdirect pathway. Long-term physical exercise can effectively improve the human respiratory and circulatory system function indicators and promote the development of nervous system.In order to discuss the mechanisms of the high level athletes' control of the brain function network and provide the experimental basis for the study of the motor control of the central nervous system, this research collects the activation images of the cortex and basal ganglia nuclei of the ordinary college students and the high level athletes and analyzes the function connection coefficient between the groups. Methods The subjects were 15 high level athletes and 15 ordinary college students. the changes of the brain structure and DTI fiber in the state of quiet and fatigue were collected by the functional magnetic resonance imaging (fMRI). Matlab software was used to compare images and data and to calculate the correlation coefficient between the related nuclear groups. Results (1) Compared with ordinary college students, the functional connectivity coefficient between the left thalamus and the left hippocampus is different in high level athletes (P<0.05). (2) The high level athletes’ functional connectivity in the left premotor area-right premotor area, left premotor area-right striatum, right premotor area-left central buckle in supplementary motor area, right premotor area-right central buckle in supplementary motor area, right premotor area-right striatum and right premotor area-left cerebellum were changed significantly after exercise fatigue (P<0.05). Conclusions The plasticity of brain function can be affected by long-term exercise training, which depends on sport training level. After exercise fatigue, the network connection system and nerve projection density change between cortical and subcortical nuclei, suggesting that exercise fatigue will change the functional connection between parts of the brain.（NSFC：31401018 SKXJX2014014).