Neuroscience
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Anxiety disorder is a major psychiatric disorder characterized by fear, worry, and excessive rumination. However, the molecular mechanisms underlying neural plasticity and anxiety remain unclear. Here, we utilized a mouse model of anxiety-like behaviors induced by the chronic administration of corticosterone (CORT) to determine the exact mechanism of each region of the fear circuits in the anxiety disorders. ⋯ Immunoblot analyses revealed that autophosphorylation of Ca2+/calmodulin-dependent protein kinase (CaMK) IIα at threonine 286 and phosphorylation of cyclic-adenosine-monophosphate response-element-binding protein (CREB) at serine 133 were markedly increased in the BLA of chronic CORT-treated mice after tone stimulation. The protein and mRNA levels of brain-derived neurotrophic factor (BDNF) also significantly increased. Our findings suggest that increased CaMKII activity and synaptic plasticity in the BLA likely account for the aberrant amygdala-dependent fear memory in chronic CORT-treated mice.
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Elevated levels of cholesterol (hypercholesterolemia) and homocysteine (hyperhomocysteinemia, HHcy) in blood have been linked with the pathology of Parkinson's disease. However, the impact of their combined effect on brain is unknown. The present study aims to investigate the effect of HHcy on dopaminergic neurons in brain of mice with hypercholesterolemia. ⋯ While neither hypercholesterolemia nor HHcy caused significant changes in the number of TH-positive neurons, hypercholesterolemia in combination with HHcy resulted in a significant loss of nigral TH-positive neurons. The results highlighted the involvement of mitochondrial complex-I dysfunction with subsequent generation of hydroxyl radicals for the observed loss of midbrain dopamine neurons in animals receiving the combined treatment. Thus, the findings of the present study pointed out the combined effect of homocysteine and cholesterol toward dopamine neuronal dysfunctions, which has substantial relevance to Parkinson's disease.
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Incorporation of a tool into the body schema is well established. Here, we assessed whether visual signals originating from the tool provide relevant cues for the perception of arm movements, as would signals originating from the arm holding it. Kinesthetic illusions were investigated by passively moving one arm (via a robotized manipulandum) and therefore the tool (a rake), using the mirror paradigm, with the reflected part being limited to the tool, the arm, or both. ⋯ Results showed that mirror vision of the moving tool was not sufficient for mirror illusions to occur, the same tool in the two hands being an essential condition. Finally, in Experiment 3, we showed that neither prior practice nor active tool use was necessary for the tool mirror illusion to occur. Altogether, these results demonstrate that the visual cues originating from the held-tool are integrated for sensing arm movement.
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Alzheimer's disease (AD) is a debilitating neurodegenerative disease, characterized by extracellular deposition of senile plaques, mostly amyloid β-protein (Aβ) and neuronal loss. The neuroprotective effects of erythropoietin (EPO) have been reported in some models of neurodegenerative disease, but because of its hematopoietic side effects, its derivatives lacking hematopoietic bioactivity is recommended. In this study, the neuroprotective effects of carbamylated erythropoietin-Fc (CEPO-Fc) against beta amyloid-induced memory deficit were evaluated. ⋯ CEPO-Fc treatment prevented the elevation of hippocampal of P38, ERK, MMP-2 activity and also Akt/GSK-3β signaling impairment induced by Aβ25-35 but it had no effect on JNK. It seems that CEPO-Fc prevents Aβ-induced learning and memory deterioration, and also modulates hippocampal MAPKs, Akt/GSK-3β and MMP-2 activity. This study suggests that CEPO-Fc can be considered as a potential therapeutic strategy for memory deficits like AD.
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Objects play vital roles in scene categorization. Although a number of studies have researched on the neural responses during object and object-based scene recognition, few studies have investigated the neural mechanism underlying object-masked scene categorization. Here, we used functional magnetic resonance imaging (fMRI) to measure the changes in brain activations and functional connectivity (FC) while subjects performed a visual scene-categorization task with different numbers of 'signature objects' masked. ⋯ Another core hub was found in left middle temporal gyrus (MTG) and its connection with middle cingulate cortex (MCC), supramarginal gyrus (SMG) and insula might serve in the processing of motor response and the semantic relations between objects and scenes. Brain-behavior correlation analysis substantiated the contributions of the FC to the different processes in the object-masked scene-categorization tasks. Altogether, the results suggest that masking of objects significantly affected the object attention, cognitive demand, top-down modulation effect, and semantic judgment.