Possible novel features of synaptic regulation during long-term facilitation in Aplysia

Most studies of molecular mechanisms of synaptic plasticity have focused on the sequence of changes either at individual synapses or in the cell nucleus. However, studies of long-term facilitation at Aplysia sensory neuron–motor neuron synapses in isolated cell culture suggest two additional features of facilitation. First, that there is also regulation of the number of synaptic contacts between two neurons, which may occur at the level of cell pair-specific branch points in the neuronal arbor. Branch points contain many molecules that are involved in protein synthesis-dependent long-term facilitation including neurotrophins and the RNA binding protein CPEB. Second, the regulation involves homeostatic feedback and tends to keep the total number of contacts between two neurons at a fairly constant level both at rest and following facilitation. That raises the question of how facilitation and homeostasis can coexist. A possible answer is suggested by the findings that they both involve spontaneous transmission and postsynaptic Ca²⁺, which can have bidirectional effects similar to LTP and LTD in hippocampus. In addition, long-term facilitation can involve a change in the set point of homeostasis, which could be encoded by plasticity molecules such as CPEB and/or PKM. A computational model based on these ideas can qualitatively simulate the basic features of both facilitation and homeostasis of the number of contacts.

Synaptic plasticity is a change in strength of the synaptic connection (postsynaptic potential or PSP) between neurons and includes increases during facilitation and decreases during depression. Plasticity is thought to underlie circuit formation during development and learning and memory in adults, and correspondingly to be defective in neurodevelopmental disorders including autism, ADHD, and schizophrenia as well as learning and memory disorders including Alzheimer''s, age-related memory loss, and drug addiction (Hawkins 2013; Hawkins et al. 2017). Most studies of molecular mechanisms of synaptic plasticity have focused on either changes at individual synapses or gene regulation in the cell nucleus. However, studies of long-term facilitation at Aplysia sensory neuron–motor neuron (SN–MN) synapses in isolated cell culture (Glanzman et al. 1990), sensitization in the intact animal (Wainwright et al. 2004), and long-term potentiation in hippocampal neurons (Antonova et al. 2001, 2009) have shown that there are also changes in the number of contacts between presynaptic varicosities and the postsynaptic neuron. We refer to these as synaptic contacts although not all of them are functional synapses (Kim et al. 2003). The number of contacts is thought to be an important determinant of the strength of the PSP (Zhang et al. 2003) and to be different for different neuron pairs. It also increases during long-term facilitation of the PSP and is thought to be a major determinant of the time course of the facilitation (Bailey and Chen 1989).As in other systems (Antonova et al. 2001, 2009; Holtmaat and Svoboda 2009), the contacts are dynamic and are continually being formed and eliminated, but the total number and the PSP remain fairly constant both at rest and during long-term facilitation (Miniaci et al. 2008; Chen et al. 2014). Furthermore, the number of contacts and the PSP return to baseline when maintenance of the facilitation is blocked, but the individual contacts are not all the same as they were before facilitation. These results have led some to suggest that memories are not stored at individual synaptic contacts, as is often supposed, but rather are stored in the nucleus (Chen et al. 2014). However, most of the previous experiments have involved a single SN and a single MN, so it has not been possible to examine the synapse specificity of the effects. Experiments with one SN and two MNs (Martin et al. 1997) or two SNs and 1 MN (Schacher et al. 1997) have shown that facilitation of the number of synaptic contacts and the PSP is specific to the stimulated synaptic pair (e.g., SN–MN1) and does not occur for the other pair (e.g., SN–MN2). These results should generalize to multiple pre- and postsynaptic partners and suggest two novel features of synaptic regulation during plasticity: (1) that the number of synaptic contacts between two neurons is regulated, and (2) that the regulation is homeostatic. We first describe those features and some of the evidence supporting them, then propose a model that could account for them and present computational modeling to illustrate the plausibility of the model.     

Suicide Risk across Latent Class Subgroups: A Test of the Generalizability of the Interpersonal Psychological Theory of Suicide

It remains unclear whether the Interpersonal Psychological Theory of Suicide (IPTS; Joiner, 2005 ) is generalizable to the population or holds more explanatory power for certain subgroups compared to others. The aim of this study was to (1) identify subgroups of individuals who endorsed suicide ideation in the past month based on a range of mental health and demographic variables, (2) compare levels of the IPTS constructs within these subgroups, and (3) test the IPTS predictions for suicide ideation and suicide attempt for each group. Latent class, negative binomial, linear, and logistic regression analyses were conducted on population‐based data obtained from 1,321 adults recruited from Facebook. Among participants reporting suicide ideation, four distinct patterns of risk factors emerged based on age and severity of mental health symptoms. Groups with highly elevated mental health symptoms reported the highest levels of thwarted belongingness and perceived burdensomeness. Tests of the IPTS interactions provided partial support for the theory, primarily in young adults with elevated mental health symptoms. Lack of support found for the IPTS predictions across the subgroups and full sample in this study raise some questions around the broad applicability of the theory.     

Meta-Analytic Analysis of Invariance Across Samples: Introducing a Method That Does Not Require Raw Data

Abstract

Invariance of surveys across different groups means that the respondents interpret the items in the same way, as reflected in similar factor loadings, for example. Invariance can be assessed using various statistical procedures, such as Multi-Group Confirmatory Factor Analysis. However, these analyses require access to raw data. Here, we introduce a meta-analytic method that requires only the factor correlation matrices of samples as input. It compares the structures of intercorrelations of factors by correlating these values across two samples, yielding a value of overall similarity for how the factors intercorrelate in different samples. This method was tested in three different ways. We conclude that the method yields useful results and can assess invariance when raw data are not available.     

《周易参同契》之"鄞鄂"义考

《汉语大词典》等释"鄞鄂"为"边界""形体"义,并认为《参同契》中的两处"鄞鄂"亦是此义.此释有两处不足:首先,"鄞鄂"的内涵要比上述释义丰富得多；其次,以《参同契》句子为例不妥,《参同契》之"鄞鄂"在炼丹术中是专门术语,有其特定的专门语义."鄞鄂"源自垠鄂写法,垠鄂包括凹凸状纹饰、开放空间或器物、某空间的四周高起貌等含义.后两种含义为各种词典所无,但它们恰恰决定了"鄞鄂"用作道教炼丹术语时的含义,即表示炼内丹的神室和炼外丹的容器.而《中华道教大辞典》及其他专业词典将"鄞鄂"理解为元神和根蒂等,是借代或是其他比喻的修辞方式,或是空间重合的另外说法.     

"忠诚"的价值:家族企业管理的核心伦理条件

家族企业的二元形态以及内外分域结构,使家族企业管理总是优先强调"忠诚之价值",并使"忠诚的价值"成为家族企业管理的核心伦理条件."基于忠诚的管理"应当成为家族企业的经营战略.忠诚对企业伦理团结的造就,作为依赖性与独立的辩证统一,"忠诚领先"作为企业核心价值原理,以及忠诚与价值创造之间的循环,是"基于忠诚的管理"的核心理念、内在矛盾、基本原则和战略目标.家族企业如何将伦理忠诚转化为家族企业的愿景,是它面临的根本的管理伦理难题.家族企业只有通过忠诚价值的意义转化和层次跃升,才能透过忠诚法则构筑家族企业的共同梦想或愿景.     

The quality and quantity of mother-toddler conflicts in two contexts

Current Psychology - The purpose of this study was to examine the quantity and quality of the mother-toddler conflicts in two contexts. Forty mother-toddler pairs participated in the study in South...     

辩太极图源于佛教一说

对于太极图和太极图说起源,目前学界存在着两种已被公认的主张,一种认为源于道藏;另外一种主张则认为源于佛教的阿赖耶识图,本文围绕寿涯的"先天地之偈"以及宗密的"十重图"(阿赖耶识图)展开研究,通过分析佛教的相关典籍来论证后一主张的合理性。