Study of dynamic characteristics of scale-free spiking neural networks based on synaptic plasticity / 生物医学工程学杂志

Biological neural networks have dual properties of small-world attributes and scale-free attributes. Most of the current researches on neural networks are based on small-world networks or scale-free networks with lower clustering coefficient, however, the real brain network is a scale-free network with small-world attributes. In this paper, a scale-free spiking neural network with high clustering coefficient and small-world attribute was constructed. The dynamic evolution process was analyzed from three aspects: synaptic regulation process, firing characteristics and complex network characteristics. The experimental results show that, as time goes by, the synaptic strength gradually decreases and tends to be stable. As a result, the connection strength of the network decreases and tends to be stable; the firing rate of neurons gradually decreases and tends to be stable, and the synchronization becomes worse; the local information transmission efficiency is stable, the global information transmission efficiency is reduced and tends to be stable, and the small-world attributes are relatively stable. The dynamic characteristics vary with time and interact with each other. The regulation of synapses is based on the firing time of neurons, and the regulation of synapses will affect the firing of neurons and complex characteristics of networks. In this paper, a scale-free spiking neural network was constructed, which has biological authenticity. It lays a foundation for the research of artificial neural network and its engineering application.

Dexmedetomidine dose for epidural anesthesia in the elderly knee arthroplasty / 中国组织工程研究

BACKGROUND:Dural elderly knee arthroplasty anesthesia is a common mode of anesthesia. Dexmedetomidine, because of good analgesic effects, is widely applied to epidural anesthesia in elderly knee replacement, but different applied dose of dexmedetomidine may lead to different results. OBJECTIVE:To explore the effects of different doses of dexmedetomidine for epidural anesthesia in elderly knee arthroplasty. METHODS:A total of 75 cases of older patients undergoing knee replacement surgery were selected and randomly divided into dexmedetomidine loading and maintenance group (25 cases), dexmedetomidine group (25 cases), and the normal saline group (25 cases), and then they were given smal doses of dexmedetomidine loading and maintenance, dexmedetomidine maintenance, intravenous infusion of normal saline. Blood pressure, heart rate, Calm/Alert Standard Score and the operation degree of forgetting were observed and compared in the three groups. The time points included T0 (after epidural anesthesia), T1 (3 minutes after medication), T2 (5 minutes after medication), T3 (10 minutes after medication), T4 (15 minutes after medication), and T5 (30 minutes after medication). RESULTS AND CONCLUSION:After the use of drugs, blood pressure and heart rate were decreased in the dexmedetomidine loading and maintenance group and dexmedetomidine group. Blood pressure and heart rate were significantly lower in the dexmedetomidine loading and maintenance group than that of dexmedetomidine maintenance group (P 0.05). These findings suggest that in elderly patients undergoing knee replacement, smal dose of dexmedetomidine continuous infusion for epidural anesthesia can achieve good effects on analgesia and sedation, can eliminate the bad memories for patients with operation, and is a scientific mode of anesthesia.