Background. Neuroimaging studies of spinal cord injury (SCI) have mostly examined the functional organization of the cortex, with only limited focus on the subcortical substrates of the injury. However, thalamus is an important modulator and sensory relay that requires investigation at a subnuclei level to gain insight into the neuroplasticity following SCI. Objective. To use resting-state functional magnetic resonance imaging to examine the functional connectivity (FC) of thalamic subnuclei in complete SCI patients. Methods. A seed-based connectivity analysis was applied for 3 thalamic subnuclei: pulvinar, mediodorsal, and ventrolateral nucleus in each hemisphere. A nonparametric 2-sample t test with permutations was applied for each of the 6 thalamic seeds to compute FC differences between 22 healthy controls and 19 complete SCI patients with paraplegia. Results. Connectivity analysis showed a decrease in the FC of the bilateral mediodorsal nucleus with right superior temporal gyrus and anterior cingulate cortex in the SCI group. Similarly, the left ventrolateral nucleus exhibited decreased FC with left superior temporal gyrus in SCI group. In contrast, left pulvinar nucleus demonstrated an increase in FC with left inferior frontal gyrus and left inferior parietal lobule in SCI group. Our findings also indicate a negative relationship between postinjury durations and thalamic FC to regions of sensorimotor and visual cortices, where longer postinjury durations (~12 months) is associated with higher negative connectivity between these regions. Conclusion. This study provides evidence for reorganization in the thalamocortical connections known to be involved in multisensory integration and affective processing, with possible implications in the generation of sensory abnormalities after SCI.
Lipopolysaccharide (LPS)-induced neuroinflammation triggers and accelerates the pathogenesis of Parkinson’s disease (PD). Carthamus tinctorius L., a traditional Chinese medicine, has been widely used for the treatment of cerebrovascular disease. Hydroxysafflor Yellow A (HSYA) is an active component of C. tinctorius. The purpose of this study was to investigate whether HSYA could attenuate LPS-induced neurotoxicity and neuroinflammation in primary mesencephalic cultures. Cell viability was measured by MTT and LDH assays. The number of tyrosine hydroxylase (TH) positive neuron was observed by immunohistochemistry. NF-κB p65 and iNOS expressions were evaluated with western blotting method. Pro-inflammatory cytokines including IL-1β and TNF-α were determined by ELISA kits. Nitric oxide (NO) content in the culture medium was assayed. The results showed that HSYA treatment significantly attenuated the LPS-induced dopaminergic neurons damage. HSYA partially inhibited the expressions of NF-κB p65 and iNOS. Furthermore, HSYA decreased the content of IL-1β, TNF-α and NO in the supernatants. Taken together, these results suggest that HSYA exerts protective effects on LPS-induced neurotoxicity in dopaminergic neurons and the mechanisms may be associated with the inhibition of inflammatory response.
Nucleus praeeminentialis (nPr) is an isthmic nucleus that has been described in the brains of electrosensory teleost fishes and a single non-electrosensory species. The nucleus receives axon collaterals of ascending medullary sensory lemniscal neurons. Axons of nPr neurons project in turn back down onto those same populations of medullary projection neurons via a descending parallel fiber system (the molecular layer or cerebellar crest). Thus nPr forms a link in a sensory feedback loop that modulates the activity of neurons that relay information from medulla to midbrain. The purpose of this study is to investigate the nature of the afferent and efferent connections of the nPr with the specific aim of investigating other sources of input into this modulatory circuit. Transport of neuronal tracers (horseradish peroxidase, DiI and dextran amines) revealed that nPr has extensive interconnections with nuclei in the basal metencephalon, cerebellum, octavolateralis column and basal medulla. A previously described source of afference, the torus semicircularis in the mesencephalon, was not indicated by our studies. Our studies suggest that in addition to regulating the sensitivity and resolution of electrosensory and mechanosensory lateral line systems, the nPr may play a role in the resolution of signal ambiguities posed by auditory or vestibular stimulation of the saccular endorgan of the inner ear.
Parkinson’s disease (PD) causes major changes in dopaminergic neurons of the brain, resulting in motor symptoms in older adults. A previous study showed that Danshensu alleviates the cognitive decline by attenuating neuroinflammation. In the present study, we investigated the neuroprotective effect of Danshensu in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. C57BL/6 mice were randomly divided into the following four groups: control, MPTP, Danshensu at 15 mg/kg, and Danshensu at 60 mg/kg. The mice were administered Danshensu intragastrically for 14 days. In the behavioral tests, Danshensu treatment alleviated motor dysfunction induced by MPTP. The number of tyrosine hydroxylase-positive neurons in the substantia nigra was significantly reduced in the MPTP group, relative to the control group; Danshensu partially blocked this reduction in tyrosine hydroxylase-positive neurons. In addition, Danshensu attenuated the reductions in striatal dopamine and 5-HT levels induced by MPTP. Danshensu also diminished the increase in Iba1-positive cells in the substantia nigra and reduced the levels of interleukin-1β and tumor necrosis factor-α in the striatum. These findings suggest that Danshensu exerts neuroprotective effects and improves motor function in PD mice, at least in part, by reducing neuroinflammation.
In this paper, a midpoint upwind scheme and a new hybrid difference scheme on tensor-product layer-adapted meshes are originally proposed for general two-dimensional singularly perturbed boundary value problems with exponential boundary layers. The higher-order truncation errors are obtained. Two numerical examples demonstrate that the midpoint upwind scheme obtains second-order convergence outside the boundary layers and almost first-order convergence in the boundary layers on the Shishkin mesh, and second-order convergence outside the boundary layers and first-order convergence in the boundary layers on the Bakhvalov-Shishkin mesh, and the new hybrid difference scheme attains second-order convergence outside the boundary layers and almost second-order convergence in the boundary layers on the Shishkin mesh.
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