Neuroscience
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It has long been known that each neuron in both the central and peripheral nervous system has a large number of active zones. Nonetheless, how active zones are regulated to maintain a homeostatic release state and response to the constantly changing environment remains poorly understood. Due to its relatively simple structure and easy accessibility, the neuromuscular synapse (NM-synapse) continues to be used as a model synapse to examine the basic nature of synaptic neurotransmission. ⋯ Furthermore, evoked quantal release has been shown to be highly non-uniform between active zones along nerve terminal branches. How these large numbers of active zones along the same nerve terminal are functionally correlated remains unclear. This review starts with the basic features of quantal neurotransmitter release, then progresses to the current knowledge on how the active zones interact with each other along the same nerve terminal.
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Motor expertise has recently been associated with differences in domain-general cognition. Studies using averaged neurophysiological signals (e.g., event-related potentials) have shown varying degree of expertise-related differences in neural activity. As a result, the precise mechanisms underlying these differences remain to be described. ⋯ The interceptive sport players showed superior behavioral performance overall on the task relative to the static sport players. Although both groups exhibited greater sample entropy across most time scales in high-conflict relative to low-conflict trials over the parietal site, this effect was only evident at coarser time scales over the midfrontal site for the interceptive sport players. Together, our results suggest that individual differences in motor expertise may be associated with difference in information-processing capacity and information integration during cognitive processing, as demonstrated by differential cognitive modulation of brain signal variability.
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The effects of muscle fatigue are known to be altered in older adults, and age-related changes in the brain are likely to be a contributing factor. However, the neural mechanisms underlying these changes are not known. The aim of the current study was to use transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) to investigate age-related changes in cortical excitability with muscle fatigue. ⋯ For TMS-EEG, the amplitude of the P30 and P180 potentials were unaffected by fatigue in older participants (P > 0.05). In contrast, the amplitude of the N45 potential in older adults was significantly reduced both during (positive cluster: mean voltage difference = 0.7 µV, P < 0.005; negative cluster: mean voltage difference = 0.9 µV, P < 0.0005) and after (mean voltage difference = 0.5 µV, P < 0.005) fatiguing exercise, whereas this response was absent in young participants. These results suggest that performance of maximal intermittent isometric exercise in old but not young adults is associated with modulation of cortical inhibition likely mediated by activation of gamma-aminobutyric acid type A receptors.
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Randomized Controlled Trial
Effects of Vortioxetine and Escitalopram on Electroencephalographic Recordings - A Randomized, Crossover Trial in Healthy Males.
The antidepressant drug vortioxetine has a multimodal action modulating neurotransmission through inhibition of the serotonin transporter and modulation of serotonin receptors. Vortioxetine has also been shown to alleviate cognitive symptoms in preclinical studies and in patients with depression. However, it is largely unclear how vortioxetine affects the brain processing in humans. ⋯ Although the global EEG changes were comparable between vortioxetine and escitalopram, subtle differences between treatment effects on the EEG in terms of effect size and regional distribution of the EEG changes were apparent. To our knowledge, the current results are the first data on how vortioxetine affects EEG in humans. The present study calls for further investigations addressing the possible electrophysiological and cognitive effects of vortioxetine.
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Corticospinal neurons (CSNs) undertake direct cortical outputs to the spinal cord and innervate the upper limb through the brachial plexus. Our previous study has shown that the contralateral middle trunk transfer to the paralyzed upper extremity due to cerebral injury can reconstruct the functional cerebral cortex and improve the function of the paralyzed upper extremity. ⋯ The three trunk-labelled CSNs were intermingled in these cortices, and mostly connected to more than two trunks, especially the middle trunk-labelled CSNs with higher proportion of co-labelled neurons. Our findings revealed the distribution features of CSNs connecting to the adjacent spinal nerves that innervate the upper limb, which can improve our understanding of the corticospinal circuits associated with motor improvement and the functional cortical reconstruction after the middle trunk transfer.