Neuroscience
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Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β and tau proteins, which are believed to lead to neural damage that translates into brain dysfunction and cognitive deficits. Brain dysfunction can be evaluated by measuring single-neuron activity (spikes), global neural activity (local field potentials, LFPs) and the interaction between them. Considering that the dynamic interactions between the hippocampal pyramidal cells and lateral septum are important for proper structure function, we used the complete septo-hippocampal preparation from 30-day-old controls and J20-AD transgenic mice to record changes in spiking activity from the lateral septum and its relationship with LFP activity from the CA1 area. ⋯ Similarly, the LFP- LFP coherence between CA1 and septum in the theta range showed lower values in J20 animals. Importantly, alterations were found before any detectable signs of cognitive deficits. Our data indicate that the disruption in the communication between hippocampus and rostral lateral septum is an early event in AD pathology and may contribute to the deficits observed during AD.
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Depression or stress is reportedly related to the overflow of inflammatory factors in the body and T cells were reported to play important roles in balancing the release of inflammatory factors through vagus nerve circuit. However, few works have been conducted to find if natural killer (NK) cells can also exert the similar function in the reported vagus nerve circuit as T cells and if there was any relationship between depression and this function. In the present study, the behavioral tests on BALB/c mice indicated that the depressant-like symptoms could be improved and simultaneously the concentrations of inflammatory factors in peripheral blood could be reduced significantly by adoptively transferring NK cells into stressed BALB/c mice. ⋯ Behavioral tests on NCG mice indicated that the antidepressant-like effects of NK cells notably declined after adoptively transferring NK cells with β2-AR deficiency or with ChAT (choline acetyltransferase) deficiency into stressed NCG mice. Simultaneously, the anti-inflammatory effects also declined significantly both in vivo and in vitro, which indicated that the antidepressant-like property of NK cells may be related to its ability of controlling the release of inflammatory factors. Taken together, we find that NK cells may balance the release of inflammatory factors in our body by transporting the information between the terminal vagal branches and macrophages, which is the mechanism that NK cells may exert antidepressant-like effects.
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Neuronal networks can produce stable oscillations and synchrony that are under tight control yet flexible enough to rapidly switch between dynamical states. The pacemaker nucleus in the weakly electric fish comprises a network of electrically coupled neurons that fire synchronously at high frequency. This activity sets the timing for an oscillating electric organ discharge with the lowest cycle-to-cycle variability of all known biological oscillators. ⋯ These responses involve a variable increase in firing frequency and a prominent desynchronization of neurons that recovers within 5 oscillation cycles. Using a previously developed computational model of the pacemaker network, we show that the frequency changes and rapid resynchronization observed experimentally are most easily explained when model neurons are interconnected more densely and with higher coupling strengths than suggested by published data. We suggest that the pacemaker network achieves both stability and flexibility by balancing coupling strength with interconnectivity and that variation in these network features may provide a substrate for species-specific evolution of electrocommunication signals.
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The amygdala is concerned with the emotional memory consolidation, and is known as a stress-vulnerable region of the brain. Slow network oscillation is considered to play roles in memory consolidation during sleep. We investigated the relationship between the sleep and oscillation in the basolateral nucleus (BL) of the amygdala, in which burst firing is preferentially observed during sleep and the slow inhibitory oscillation is recorded from projection neuron. ⋯ The spike threshold of interneurons was increased and the power of the periodic excitatory transmission was reduced in the SD rats. Moreover, a reduction in input resistance in projection neurons was observed in SD rats without significant difference in the excitability which was measured by the spike number induced by depolarizing currents. These results suggest that SD stress affects the network oscillatory property accompanied by changes of individual neuronal excitability and synaptic communications.
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Intracortical inhibitory modulation seems crucial for an intact motor control and motor learning. However, the influence of long(er) term training on short-interval intracortical inhibition (SICI) is scarcely investigated. With respect to balance, it was previously shown that with increasing postural task difficulty, SICI decreased but the effect of balance training (BT) is unknown. ⋯ The present study confirms previous findings of task-specific modulation of SICI when balancing. More importantly, training was shown to increase SICI and this increase was correlated with changes in balance performance. Thus, changes in SICI seem to be involved not only for the control but also when adapting upright posture with training.