The dynamic mechanism of a novel stochastic neural firing pattern observed in a real biological system

In the experimental neural pacemaker of a rat, a novel firing pattern has been discovered. This pattern was generated between the period 2 firing pattern and the period 3 firing pattern during the periodic adding bifurcation and inverse periodic adding bifurcation. The pattern was observed and analyzed in the present investigation. The composition of this novel firing pattern could be regarded as a transition between a string of period 2 burst and a string of period 3 burst without single period 2 or period 3 burst, which was different from those chaotic and stochastic neural firing patterns in previous reports. It was identified to be stochastic by the inter-event intervals (IEIs) analysis, although it exhibited chaos-like characteristics with the results of the inter-spike intervals (ISIs) analysis. The numerical simulation suggested that the new pattern observed in the real biological system could be simulated in the stochastic Chay model but not in the deterministic model. With the signal to noise ratio (SNR) analysis and bifurcation analysis, this novel firing pattern was considered to be generated by stochastic resonance under the influence of noise near the periodic adding (inverse) bifurcation point. The probability analysis of transformed binary chain further confirmed that the origin of stochastic and chaos (deterministic)-like characteristics of this novel firing pattern.     

干细胞生物材料来源及其伦理风险的系统性综述

对干细胞生物材料来源及其伦理风险进行系统性综述。干细胞生物材料来源主要有骨髓、脂肪、胚胎、脐带等组织。本次纳入的178篇有关不同来源的干细胞伦理风险文献中,近60%篇次是特指间充质干细胞、胚胎干细胞和造血干细胞的伦理风险,且对生物材料供者和干细胞受者以及社会伦理风险关注最多的是胚胎干细胞相关风险。此外,供者的伦理风险主要在招募、知情同意、公平性等方面。作者建议干细胞来源的生物材料供者应该得到充分的知情同意,干细胞生物材料的获取需要有严格的伦理管控,以使干细胞研究更符合伦理规范,保护供者的权益。

     

生殖性复制与医疗性复制之伦理区分

目前,各国政府和学术界对生殖性复制持否定态度是一致的,但对医疗性复制却存在激烈的争论。争论主要涉及人类胚胎的来源、胚胎的地位,以及胚胎干细胞成果应用的可接受性。     

伦理,胚胎和干细胞研究

道德是关于规则、直觉、理解和观点的一个复杂系统。而后者影响着我们相互间处理事务的方式。它们交叉地渗入我们的道德思考。这种思维与胚胎、干细胞的伦理密切相关,因为胚胎和干细胞涉及我们对与治疗和移植组织有关的人的生命及其启始问题。就像在许多对待生命及其可以阐释的研究方法方面,要有一个道德的思辩历程一样,解决这些问题,部分地需要讨论,部分地需要回答。只有在我们认定这种讨论能够融入应用干细胞治疗的胚胎及其类源和人体组织的使用中时,我们才会清楚,大多数人体不同部位的干细胞应用是经过了对人的生命启始、我们儿童、家庭进行了思考。     

Persistence and accommodation in short‐term priming and other perceptual paradigms: temporal segregation through synaptic depression

Perceptual input changes constantly in an unpredictable fashion, often changing before our somewhat sluggish perceptual systems have adequately processed this input. This can give rise to source confusion—how do we know whether a given perceptual activation is due to the current input, or a previous input that had yet to be completely processed? We propose that activity‐dependent neural accommodation naturally limits this source confusion by suppressing items once they have been identified. We review behavioral paradigms from different literatures that measure the correlates of persistence and accommodation. Of the various accommodative mechanisms, we focus on synaptic depression, deriving a rate‐coded expression that can be used to produce accommodating dynamics in any neural network with real valued activation. We implement this expression in a hierarchical model of perception termed, “a neural mechanism for responding optimally with unknown sources of evidence” (nROUSE). This model can be viewed as a more detailed version of the more abstract ROUSE model of Huber, Shiffrin, Lyle, and Ruys (2001), which produces accommodated levels of feature evidence through an optimal calculation. We apply nROUSE to three short‐term priming experiments that manipulated prime duration.     

Lexical effects on compensation for coarticulation: the ghost of Christmash past

The question of when and how bottom‐up input is integrated with top‐down knowledge has been debated extensively within cognition and perception, and particularly within language processing. A long running debate about the architecture of the spoken‐word recognition system has centered on the locus of lexical effects on phonemic processing: does lexical knowledge influence phoneme perception through feedback, or post‐perceptually in a purely feedforward system? Elman and McClelland (1988) reported that lexically restored ambiguous phonemes influenced the perception of the following phoneme, supporting models with feedback from lexical to phonemic representations. Subsequently, several authors have argued that these results can be fully accounted for by diphone transitional probabilities in a feedforward system (Cairns et al., 1995; Pitt & McQueen, 1998). We report results strongly favoring the original lexical feedback explanation: lexical effects were present even when transitional probability biases were opposite to those of lexical biases.     

Longitudinal Assessment of Pain, Coping, and Daily Functioning in Children with Sickle Cell Disease Receiving Pain Management Skills Training

Objective. To conduct intensive pain management skills training (IST) in children with sickle cell disease (SCD) and their parents and to comprehensively evaluate pain, coping, and daily functioning in children pre, immediately post, and 3 months following treatment. Methods. Three children who received IST in nonpharmacological and pharmacological pain management strategies completed a Coping Strategies Questionnaire (CSQ) at pre, post, and follow-up assessments, and daily pain and activity diaries for 18 weeks, spanning from 1 week pretreatment to 11 weeks posttreatment. Results. From pre- to posttreatment, 1 child receiving IST indicated increased report of active coping attempts and all 3 children indicated decreased report of negative thinking on the CSQ. Participants in IST used coping skills on 90% of days with pain and reported the skills to be moderately helpful on the daily diaries. For daily activities such as eating dinner, playing with friends, and hours slept, children participated similarly on days with pain and days without pain during the posttreatment period. Given the small number of participants in this study, individual cases are discussed to highlight similarities and differences in how participants responded to the treatment and during the 3-month follow-up period. Conclusions. In this pilot study, each participant showed improvement in coping and daily functioning after completing the IST program. Individual differences in response to treatment indicate the need for more targeted intervention programs that incorporate pharmacological and nonpharmacological components. The results of this study highlight both the promise and the complications of conducting comprehensive pain intervention and functional outcome studies in children with SCD.     

复述、提取抑制与有意遗忘的实验研究

有意遗忘是关于记忆研究的另一种实验范式,对于在实验中出现的要求遗忘的学习项目的记忆成绩差于要求记忆的项目的结果,目前主人存在着两种理论解释：基于编码的理论和基于提取抑制的理论。该实验运用单字提示方式,采用控制较为严密的补笔测验方法和加入所谓的“无关项”,对有意遗忘的心理过程进行进一步的探讨,实验表明：在单了提示方式下,被试在进行有意遗忘的过程中,既对记忆项进行了有意的复述又对遗忘项产生了提取抑制。     

Powered-Two-Wheelers kinematic characteristics and interactions during filtering and overtaking in urban arterials

The present paper focuses on the Powered-Two-Wheelers (PTWs) kinematic characteristics and their interactions with the rest of traffic in urban arterials. The factors that may affect the likelihood of PTW drivers to accept critical spacing during filtering and overtaking are also investigated using trajectory data collected from video recordings. The distributional characteristics of the PTW kinematic parameters showed that the patterns of filtering and overtaking have several differences. Further results using Logit models show that PTW speed difference with the rest of traffic, spacing, the existence of heavy vehicles and the occurrence of platoon of moving PTWs (in which the leader is the reference PTW) are significant factors related to the probability of driving in critical spaces through traffic. The likelihood of accepting critical lateral distance from the vehicle being overtaken may be related to the adjacent lane spacing, the speed difference and the existence of a platoon of PTWs. A comparative study between Logit models and equivalent structures of neural networks showed that, in the specific application, neural networks were found to perform better than the Logit models in terms of the model’s discrimination power.