Neuroscience
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Absence seizures are known to result from disturbances within the cortico-thalamocortical network, which remains partially synchronous under normal conditions but switches to a state of hypersynchronicity and hyperexcitability during absence seizures. There is evidence to suggest that impaired GABAergic inhibitory function within the thalamus could contribute to the generation of hypersynchronous oscillations in some animal models of absence epilepsy. Recently, we demonstrated region-specific alterations in the tissue expression level of GABAA receptors (GABA(A)Rs) α1 and β2 subunits within the thalamus of the stargazer mouse model of absence epilepsy. ⋯ Furthermore, we investigated whether tissue expression of GABA(A)R subunits α4 and δ, which constitute part of tonic GABA(A)Rs in the VP region, is altered in the stargazer mouse. Semi-quantitative Western blotting showed a significant increase in GABA(A)R α4 and δ subunits in the VP region of stargazer thalamus, which would indicate an increase in tonic GABA(A)R expression. Our findings show that there are changes in the levels of both phasic and tonic GABA(A)Rs in the VP thalamus; altered GABAergic inhibition within the VP could be one of many mechanisms contributing to the generation of absence seizures in this model.
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Recent functional magnetic resonance imaging (fMRI) studies consistently revealed contributions of fronto-parietal and related networks to the execution of a visuospatial judgment task, the so-called "Clock Task". However, due to the low temporal resolution of fMRI, the exact cortical dynamics and timing of processing during task performance could not be resolved until now. In order to clarify the detailed cortical activity and temporal dynamics, 14 healthy subjects performed an established version of the "Clock Task", which comprises a visuospatial task (angle discrimination) and a control task (color discrimination) with the same stimulus material, in an electroencephalography (EEG) experiment. ⋯ We divided this window in two parts: an early phase - from 192 ms to ∼440 ms, and a late phase - from ∼440 ms to 776 ms. For both tasks, the order of network activations and the types of networks were the same, but, in each phase, activations for the two conditions were dominated by differing network states with divergent temporal dynamics. Our results provide an important basis for the assessment of deviations in processing dynamics during visuospatial tasks in clinical populations.
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The clinical differential diagnosis between the Parkinson variant of multiple system atrophy (MSA-P) and Parkinson's disease (PD) is difficult in early stages. To identify objective markers for differential diagnosis, we combined the novel tract-based spatial statistics (TBSS) and region of interest (ROI) analyses for the first time to investigate three groups (15 MSA-P, 20 PD patients and 20 controls) with diffusion tensor imaging data. By TBSS, we performed pairwise comparisons of fractional anisotropy (FA), mean diffusivity, radial diffusivity (RD) and axial diffusivity maps. ⋯ FA/RD values in bilateral corticospinal tract (CST) and left anterior thalamic radiation (ATR) in MSA-P were significantly different from PD or controls, and significantly correlated with clinical data. These findings indicated that the abnormalities of left ATR and bilateral CST were specific for MSA-P relative to PD or controls, and seemed to be promising for differential diagnosis. Furthermore, it may be useful for severity assessment of MSA-P.
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Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common type of dementia among older people. The number of patients with AD will grow rapidly each year and AD is the fifth leading cause of death for those aged 65 and older. In recent years, one of the main challenges for medical investigators has been the early diagnosis of patients with AD because an early diagnosis can provide greater opportunities for patients to be eligible for more clinical trials and they will have enough time to plan for future, medical and financial decisions. ⋯ We selected 50 percent of the MRIs randomly for use in training the classifiers, 25 percent for validation and we used 25 percent for the testing phase. The technique proposed here yielded the best overall classification results between AD and MCI (accuracy 94.88%, sensitivity 94.18%, and specificity 95.55%), and for pairs of the MCI and HC (accuracy 95.59%, sensitivity 95.89% and specificity 95.34%). These results were achieved using maximum order 30 of PZM and the pattern recognition network with the scaled conjugate gradient (SCG) back-propagation training algorithm as a classifier.
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Exposure to an immune challenge during peripuberty/adolescence, but not in adulthood, can cause enduring alterations in reproductive and non-reproductive behaviors. This suggests that the peripubertal/adolescent brain might respond differently to a stressor, like an immune challenge, than the adult brain. The goal of this study was to examine whether there are age and sex differences in the acute response to an immune challenge. ⋯ LPS treatment also significantly increased serum CORT concentration in all mice regardless of sex and age. However, adult female mice treated with LPS showed significantly greater serum CORT concentration compared to adult and peripubertal/adolescent males and peripubertal/adolescent females treated with LPS. These findings support our hypothesis and suggest that there are important age and sex differences in acute immune response, which may allude to mechanisms for the enduring behavioral alterations, observed previously in mice exposed to an immune challenge during puberty but not in adulthood.