How the mechanisms of long-term synaptic potentiation and depression serve experience-dependent plasticity in primary visual cortex

Donald Hebb chose visual learning in primary visual cortex (V1) of the rodent to exemplify his theories of how the brain stores information through long-lasting homosynaptic plasticity. Here, we revisit V1 to consider roles for bidirectional ‘Hebbian’ plasticity in the modification of vision through experience. First, we discuss the consequences of monocular deprivation (MD) in the mouse, which have been studied by many laboratories over many years, and the evidence that synaptic depression of excitatory input from the thalamus is a primary contributor to the loss of visual cortical responsiveness to stimuli viewed through the deprived eye. Second, we describe a less studied, but no less interesting form of plasticity in the visual cortex known as stimulus-selective response potentiation (SRP). SRP results in increases in the response of V1 to a visual stimulus through repeated viewing and bears all the hallmarks of perceptual learning. We describe evidence implicating an important role for potentiation of thalamo-cortical synapses in SRP. In addition, we present new data indicating that there are some features of this form of plasticity that cannot be fully accounted for by such feed-forward Hebbian plasticity, suggesting contributions from intra-cortical circuit components.     

Inbreeding and inbreeding depression in endangered red wolves (Canis rufus)

In natural populations, the expression and severity of inbreeding depression can vary widely across taxa. Describing processes that influence the extent of inbreeding and inbreeding depression aid in our understanding of the evolutionary history of mating systems such as cooperative breeding and nonrandom mate selection. Such findings also help shape wildlife conservation theory because inbreeding depression reduces the viability of small populations. We evaluated the extent of inbreeding and inbreeding depression in a small, re‐introduced population of red wolves (Canis rufus) in North Carolina. Since red wolves were first re‐introduced in 1987, pedigree inbreeding coefficients (f) increased considerably and almost every wild born wolf was inbred (average f = 0.154 and max f = 0.383). The large inbreeding coefficients were due to both background relatedness associated with few founders and numerous close relative matings. Inbreeding depression was most evident for adult body size and generally absent for direct fitness measures such as reproductive success and survival; no lethal equivalents (LE = 0.00) were detected in juvenile survival. The lack of strong inbreeding depression in direct measures of fitness could be due to a founder effect or because there were no outbred individuals for comparison. Our results highlight the variable expression of inbreeding depression across traits and the need to measure a number of different traits when evaluating inbreeding depression in a wild population.     

体育锻炼与心理健康:认知、焦虑、抑郁和自我概念的研究进展

体育锻炼对心理健康的影响主要研究成果集中在认知功能,焦虑和抑郁,以及自我概念。体育锻炼可以有助于认知功能的提高,减少老年人的认知退化以及改善智力落后儿童的认知能力。体育锻炼可以作为焦虑和抑郁的预防和治疗的手段之一。体育锻炼也可以提高自我概念,有助于良好心理品质的形成。本文对以上三个方面的研究进行综述,并提出研究中的困难和今后研究的展望。     

认知疗法联合舍曲林治疗产后抑郁症患者的临床疗效研究

目的：探讨认知疗法合并舍曲林治疗产后抑郁症患者的临床疗效。方法：将本院2011年10月至2012年7月收治的76例产后抑郁症患者按随机数字表法分为认知疗法合并舍曲林治疗组（试验组,38例）和舍曲林单独治疗组（对照组,38例）,进行临床随机双盲对照试验,采用17项汉密尔顿抑郁量表（HamiltonDepressionRatingScale,HAMD）、临床整体量表一疗效总评估量表（ClinicalGlobalImpression,CGI）评价和比较两组的临床疗效。结果：（1）试验组的有效率显著高于对照组,差异有统计学意义[92．11％VS81．58％）,P〈0．01],试验组第2、3阶段的临床有效率均显著高于对照组,差异有统计学意义（P〈0．05）。（2）与治疗前相比,两组患者治疗后的HAMD、CGI．SI总分均降低,差异有统计学意义（P〈0．01）;治疗第1、2、3阶段,试验组HAMD、CGI—SI减分值均显著高于对照组,差异有统计学意义（P〈0．05）。结论：认知疗法联合舍曲林治疗产后抑郁症的短期治疗内疗效显著优于舍曲林单独治疗。     

聚焦抑郁症治疗药物

抗抑郁药市场潜藏着巨大商机。全世界约有3.5 亿人患有抑郁症,该疾病为全球范围内致残的第一大诱因。在美国,9.1% 的人患有抑郁症。在世界范围内,接受抑郁症治疗的患者不到实际患病人数的一半,在一些国家甚至还不到十分之一。较高的发病率,再加上较低的市场渗透率,抗抑郁药市场的前景非常广阔。但开发抗抑郁药的公司同样面临许多挑战。心理治疗仍然是优于药物治疗的一线疗法。在药物治疗方面,近年来大量上市的仿制药使品牌抗抑郁药的市场价值缩水一半。由于儿童、青少年和青壮年用药患者的自杀率有所增加,现在要求所有抗抑郁药必须在说明书中加入黑框警告,这直接影响了药物在这些人群中的使用,成为抗抑郁新药面临的又一困难。许多患者在开始接受治疗的第一年内都会更换最初使用的药物,这对于药企而言,既是机遇也是挑战。目前抑郁症的发病机制尚未充分阐明,虽然这有利于开发具有全新作用机制的新药,但也使该治疗领域面临重重困难。     

Desvenlafaxine prevents white matter injury and improves the decreased phosphorylation of the rate‐limiting enzyme of cholesterol synthesis in a chronic mouse model of depression

Serotonin/norepinephrine reuptake inhibitors antidepressants exert their effects by increasing serotonin and norepinephrine in the synaptic cleft. Studies show it takes 2–3 weeks for the mood‐enhancing effects, which indicate other mechanisms may underlie their treatment effects. Here, we investigated the role of white matter in treatment and pathogenesis of depression using an unpredictable chronic mild stress (UCMS) mouse model. Desvenlafaxine (DVS) was orally administrated to UCMS mice at the dose of 10 mg/kg/day 1 week before they went through a 7‐week stress procedure and lasted for over 8 weeks before the mice were killed. No significant changes were found for protein markers of neurons and astrocytes in UCMS mice. However, myelin and oligodendrocyte‐related proteins were significantly reduced in UCMS mice. DVS prevented the stress‐induced injury to white matter and the decrease of phosphorylated 5′‐AMP‐activated protein kinase and 3‐hydroxy‐3‐methyl‐glutaryl‐CoA reductase protein expression. DVS increased open arm entries in an elevated plus‐maze test, sucrose consumption in the sucrose preference test and decreased immobility in tail suspension and forced swimming tests. These findings suggest that stress induces depression‐like behaviors and white matter deficits in UCMS mice. DVS may ameliorate the oligodendrocyte dysfunction by affecting cholesterol synthesis, alleviating the depression‐like phenotypes in these mice.

     

亚热带峰丛洼地恢复演替植物群落的数量分类和排序——以广西马山弄拉峰丛洼地为例

采用双向指示种分析法(TWINSPAN)和除趋势对应分析(DCA)对弄拉峰丛洼地恢复演替植物群落进行数量分类和排序。TWINSPAN将20个样方分为10个组,根据植被分类的原则划分为10个群丛,论述了各群丛的群落学特征。20个样方的DCA排序结果反映了恢复演替群落与环境梯度的关系,表明影响群丛分布格局的主导生态因子为恢复时间、人为干扰及露石率。DCA排序将53个种分为4个种组,影响峰丛洼地恢复演替群落及其物种分布格局的主导生态因子为恢复时间、岩性和水分等。各物种在排序轴上的位置反映了种组成员的生态适应性及其在群落中的重要性和更新生态位。     

Population type can influence the magnitude of inbreeding depression in Clarkia concinna (Onagraceae)

Fragmented populations may face high risk of extinction due to the deleterious consequences of increased inbreeding or of genetic drift in small and isolated populations. Theories on the mechanisms of inbreeding depression predict that the severity of inbreeding depression can eventually decrease in populations that persistently inbreed, and hence populations that are isolated through habitat fragmentation might experience a decrease in inbreeding depression over time. In this study, we tested this hypothesis using the patchily distributed, outcrossing annual plant, Clarkia concinna concinna (Onagraceae), which naturally experiences many fragmentation effects. We collected seeds from isolated and central subpopulations and created artificially inbred and outcrossed lines. Progeny from these crosses were planted into the field and greenhouse and assayed for fitness traits over the course of a growing season. Overall, inbreeding depression was substantial, ranging as high as 0.76 (for cumulative fitness in the field), and significant for plant height, fecundity, and above-ground biomass in all experiments. No inbreeding depression was detected for germination or survival rates in the greenhouse experiments, but in the field, survival was significantly depressed for inbred progeny. There was no evidence to support our hypothesis that increased inbreeding in isolated populations would lead to the purging of deleterious alleles and a decrease in the severity inbreeding depression. The most likely hypothesis to explain our results is that purging is not occurring more strongly in the isolated populations due to details of a number of genetic factors (e.g., selection against deleterious alleles is inconsistent or insufficient, or drift has caused fixation of deleterious alleles in these populations). This study supports the view that even when inbreeding depression is predicted to be less problematic, it may still be an important force influencing the fitness of populations. This revised version was published online in July 2006 with corrections to the Cover Date.