Neuroscience
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The perirhinal (PER) - lateral entorhinal (LEC) network plays a pivotal role in the information transfer between the neocortex and the hippocampus. Anatomical studies have shown that the connectivity is organized bi-directionally: the superficial layers consist of projections running from the neocortex via the PER-LEC network to the hippocampus while the deep layers form the output pathway back to the neocortex. Although these pathways are characterized anatomically, the functional organization of the superficial and deep connections in the PER-LEC network remains to be revealed. ⋯ We performed paired recordings in superficial layer principal neurons and parvalbumin (PV) expressing interneurons to address how this window of opportunity for spiking is affected in superficial principal neurons. The PV interneuron population initiated inhibition at a very consistent timing with increasing stimulus intensity, whereas the excitation temporally shifted to ensure action potential firing. These data indicate that superficial principal neurons can transmit cortical synaptic input through the PER-LEC network because these neurons have a favorable window of opportunity for spiking in contrast to deep neurons.
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The sphenopalatine ganglion (SPG) is a gathering of the cell bodies of parasympathetic fibers that dominate the nasal gland, lacrimal gland and cerebral blood vessels. The SPG controls nasal secretions, tears, and the dilation of cerebral blood vessels. However, it is unclear how serotonin regulates SPG functions. ⋯ The 5-HT3A receptor, 5-HT3B receptor, and AADC were expressed in 96.5% ± 1.0%, 29.7% ± 10.7%, and 57.4% ± 2.9% of neuronal cell bodies in the SPG, respectively, indicating that the 5-HT3A receptor was virtually expressed in all SPG neurons. Our results on the expression of these critical serotonin system genes in the parasympathetic SPG provide insight into the pathogenetics of rhinitis, conjunctivitis and headache. Furthermore, our findings suggest that targeting the 5-HT3A receptor might have therapeutic potential in the treatment of these ailments.
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Individuals continuously confronted with various stresses in modern life generate high levels of cortisol (corticosterone in rodents), the major glucocorticoid secreted by adrenal gland when hypothalamic-pituitary-adrenal axis is activated. Chronic stress can induce constant release of glucocorticoid and cause many serious health problems, such as mental disorders, cardiovascular diseases and autoimmune diseases. Many studies have suggested the neurotoxic effect of corticosterone is mediated through increased oxidative stress and apoptosis. ⋯ By utilizing a cellular stress model of exposing cells to corticosterone, our study found that there were a dose-dependent decrease in SIRT1 and an increase in LC3B II/I expressions with increasing concentrations of corticosterone. In combination with SIRT1 overexpression and knockdown plasmids, the regulation of SIRT1 expression in vitro demonstrated that SIRT can inhibit corticosterone-induced autophagy and enhance cell apoptosis. These findings might help us better understand the role of SIRT1 and autophagy activation in chronic stress.
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Randomized Controlled Trial
Upper Limb Motor Training Based on Task-Oriented Exercises Induces Functional Brain Reorganization in Patients with Multiple Sclerosis.
The aim of this work was to investigate changes in motor performance and in the brain activation pattern during finger movements, following upper limb motor training in multiple sclerosis. Thirty people with multiple sclerosis with mild upper limb sensorimotor deficits were randomly allocated to one of two groups: the experimental group (n = 15) received an upper limb treatment based on voluntary task-oriented movements; the control group (n = 15) underwent passive mobilization of shoulder, elbow, wrist and fingers. All participants completed three treatment sessions per week for eight weeks. ⋯ However, only the experimental group showed increased lateralization towards more normal brain activation following treatment, with activation clusters mainly located in the left brain hemisphere and right cerebellum. In conclusion, both active and passive interventions were effective in improving motor performance. However, only the treatment based on voluntary task-oriented movements could induce changes in brain activity that may have reflected skill acquisition by the right hand, reducing the activation of compensatory areas and decreasing brain resource demand.