The dynamics of learning and behavioral flexibility

Fundamental to behavior is the capacity to distinguish beneficial from detrimental environmental stimuli. In this issue of Neuron, a new study by Morrison et?al. shows that underlying these processes are qualitatively different dynamical interactions between brain structures involved in processing the value of environmental stimuli.     

Infectious disease,behavioural flexibility and the evolution of culture in primates

Culturally transmitted traits are observed in a wide array of animal species, yet we understand little about the costs of the behavioural patterns that underlie culture, such as innovation and social learning. We propose that infectious diseases are a significant cost associated with cultural transmission. We investigated two hypotheses that may explain such a connection: that social learning and exploratory behaviours (specifically, innovation and extractive foraging) either compensate for existing infection or increase exposure to infectious agents. We used Bayesian comparative methods, controlling for sampling effort, body mass, group size, geographical range size, terrestriality, latitude and phylogenetic uncertainty. Across 127 primate species, we found a positive association between pathogen richness and rates of innovation, extractive foraging and social learning. This relationship was driven by two independent phenomena: socially contagious diseases were positively associated with rates of social learning, and environmentally transmitted diseases were positively associated with rates of exploration. Because higher pathogen burdens can contribute to morbidity and mortality, we propose that parasitism is a significant cost associated with the behavioural patterns that underpin culture, and that increased pathogen exposure is likely to have played an important role in the evolution of culture in both non-human primates and humans.     

Olfactory evolution and behavioral ecology in primates

Primates are usually thought of as "visual" mammals, and several comparative studies have emphasized the role of vision in primate neural and sociocognitive specialization. Here I explore the role of olfactory systems, using phylogenetic analysis of comparative volumetric data. The relative sizes of the main olfactory bulb (MOB) and accessory olfactory bulb (AOB) tend to show different evolutionary patterns in accordance with their different functions. Although there is some evidence of correlated evolution of the two systems, this is apparent in only one clade (the strepsirhines). As predicted, the MOBs correlate predominantly with ecological factors (activity period and diet), while the AOBs correlate with social and mating systems. Related olfactory structures (i.e., the piriform cortex and amygdala) exhibit correlated evolution with the AOBs but not with the MOBs, and the corticobasolateral part of the amygdala exhibits a correlation with social group size in platyrrhines similar to that observed for the AOB. These social system correlations support the idea that there is an olfactory dimension to the concept of the social brain.     

Balancing organization and flexibility in foraging dynamics

Proper pattern organization and reorganization are central problems facing many biological networks which thrive in fluctuating environments. However, in many cases the mechanisms that organize system activity oppose those that support behavioral flexibility. Thus, a balance between pattern organization and pattern flexibility is critically important for overall biological fitness. We study this balance in the foraging strategies of ant colonies exploiting food in dynamic environments. We present discrete time and space simulations of colony activity that uses a pheromone-based recruitment strategy biasing foraging towards a food source. After food relocation, the pheromone must evaporate sufficiently before foraging can shift colony attention to a new food source. The amount of food consumed within the dynamic environment depends non-monotonically on the pheromone evaporation time constant—with maximal consumption occurring at a time constant which balances trail formation and trail flexibility. A deterministic, ‘mean field’ model of pheromone and foragers on trails mimics our colony simulations. This reduced framework captures the essence of the flexibility-organization balance, and relates optimal pheromone evaporation to the timescale of the dynamic environment. We expect that the principles exposed in our study will generalize and motivate novel analysis across a broad range systems biology.     

非人灵长类觅食行为生态学研究进展

觅食行为生态学是动物生态学研究的主要内容之一.从食物选择研究方法、食物选择策略机制、觅食行为的影响因素等方面综述非人灵长类动物觅食行为生态学研究进展.食物选择策略和活动时间分配是觅食行为生态学研究的主要内容.非人灵长类动物觅食行为生态学的研究对动物保护、人工驯养和繁殖具有重要意义.     

SARS-CoV-2 viral dynamics in non-human primates

Non-human primates infected with SARS-CoV-2 exhibit mild clinical signs. Here we used a mathematical model to characterize in detail the viral dynamics in 31 cynomolgus macaques for which nasopharyngeal and tracheal viral load were frequently assessed. We identified that infected cells had a large burst size (>10⁴ virus) and a within-host reproductive basic number of approximately 6 and 4 in nasopharyngeal and tracheal compartment, respectively. After peak viral load, infected cells were rapidly lost with a half-life of 9 hours, with no significant association between cytokine elevation and clearance, leading to a median time to viral clearance of 10 days, consistent with observations in mild human infections. Given these parameter estimates, we predict that a prophylactic treatment blocking 90% of viral production or viral infection could prevent viral growth. In conclusion, our results provide estimates of SARS-CoV-2 viral kinetic parameters in an experimental model of mild infection and they provide means to assess the efficacy of future antiviral treatments.     

Individual differences in temperament and behavioral management practices for nonhuman primates

Effective behavioral management plans are tailored to unique behavioral patterns of each individual species. However, even within a species behavioral needs of individuals can vary. Factors such as age, sex, and temperament can affect behavioral needs of individuals. While some of these factors, such as age and sex, are taken into account, other factors, such as an individual's temperament, are rarely specifically provided for in behavioral management plans. However, temperament may affect how animals respond to socialization, positive reinforcement training and other forms of enrichment. This review will examine how individual differences in temperament might affect, or be affected by, behavioral management practices for captive primates. Measuring temperament may help us predict outcome of social introductions. It can also predict which animals may be difficult to train using traditional methods. Further, knowledge of temperament may be able to help identify individuals at risk for development of behavioral problems. Taken together, understanding individual differences in temperament of captive primates can help guide behavioral management decisions.     

Control, choice, and assessments of the value of behavioral management to nonhuman primates in captivity

Many people have devoted considerable effort to enhancing the environments of nonhuman primates in captivity. There is substantial motivation to develop experimental, analytical, and interpretational frameworks to enable objective measurements of the value of environmental enrichment/behavioral management efforts. The consumer-demand approach is a framework not frequently implemented in studies of nonhuman primate welfare but profitably used in studies of the welfare of nonhuman animals in agriculture. Preference studies, in which primates can voluntarily choose to socialize or to participate in training, may be the best current examples of a consumer-demand-like approach to assessing the effects of captive management strategies on primate welfare. Additional work in this area would be beneficial; however, there are potential ethical constraints on purposefully subjecting primates to adverse circumstances to measure their demand for a resource. Primate welfare researchers need to design consumer-demand studies with obstacles that will help measure the relative value of resources to captive primates without compromising the welfare they are attempting to evaluate and enhance.     

Transgenic mice lacking NMDAR-dependent LTD exhibit deficits in behavioral flexibility

While most studies have focused on the role of long-term potentiation in behavior, far less is known about the role of long-term depression (LTD). To examine the potential involvement of LTD in learning and memory, we generated transgenic mice that express a fragment of the SV40 small t antigen known to inhibit protein phosphatase 2A (PP2A). Small t antigen expression blocked both stimulus-induced and chemically induced NMDAR-dependent LTD at Schaffer collateral synapses but did not affect potentiation, depotentiation, or mGluR-dependent LTD. This physiological phenotype was associated with deficits in behavioral flexibility in both the Morris water maze and a delayed nonmatch to place T-maze task, suggesting that NMDAR-dependent LTD is required for behavioral flexibility and may act by weakening previously encoded memory traces when new information is learned.     

中国非人灵长类物种的行为偏侧研究进展

行为偏侧是指动物进行某一行为时偏好使用某一侧肢体或感觉器官。行为偏侧作为脑偏侧所对应的可观测的行为指标,是动物行为适应性进化的代表性特征之一,它在个体水平上影响着个体适合度,在群体水平上是社会性物种的一种进化稳定策略,具有重要的生态和进化意义。中国非人灵长类资源丰富,而中国非人灵长类的行为偏侧研究起步较晚,始于二十世纪八十年代。本文系统归纳中国非人灵长类物种的行为偏侧研究进展,并基于当前研究现状,为今后发展提出积极建议。     

The flexibility and dynamics of protein disulfide isomerase

We have studied the mobility of the multidomain folding catalyst, protein disulfide isomerase (PDI), by a coarse‐graining approach based on flexibility. We analyze our simulations of yeast PDI (yPDI) using measures of backbone movement, relative positions and orientations of domains, and distances between functional sites. We find that there is interdomain flexibility at every interdomain junction but these show very different characteristics. The extent of interdomain flexibility is such that yPDI's two active sites can approach much more closely than is found in crystal structures—and indeed hinge motion to bring these sites into proximity is the lowest energy normal mode of motion of the protein. The flexibility predicted for yPDI (based on one structure) includes the other known conformation of yPDI and is consistent with (i) the mobility observed experimentally for mammalian PDI and (ii) molecular dynamics. We also observe intradomain flexibility and clear differences between the domains in their propensity for internal motion. Our results suggest that PDI flexibility enables it to interact with many different partner molecules of widely different sizes and shapes, and highlights considerable similarities of yPDI and mammalian PDI. Proteins 2016; 84:1776–1785. © 2016 Wiley Periodicals, Inc.     

The roles of ecological and behavioral observation in species recognition among primates

Closely related living mammal species present numerous difficulties of recognition and delineation, not least because populations as well as individual organisms fulfill both genetic and economic functions. However, since species are often distributed geographically across multiple ecosystems or environments, it is evident that species as wholes, except where coterminous with the local populations of which they are composed, cannot be said to play unitary ecological roles. Aspects of the economic activity of organisms thus may not be admitted as elements in species recognition. Those who study the behavior of mammals in their natural habitats must therefore focus upon behaviors which preserve the genetic integrity of species if they wish to contribute to the systematic question of species identification. «Isolation» concepts of species are not served by data of this kind, since they emphasize interspecies discontinuities; the «recognition» concept of species, however, specifically focuses upon behaviors of this kind as they contribute to the «Specific-Mate Recognition System». Among primates such behaviors are likely to involve signalling of various kinds; where this is visual it is reasonable to expect to find morphological or chromatic correlates; where such cues are auditory or, to a lesser extent, olfactory, it is less probable that such correlates will be found to exist.     

Endocrine control of spermatogenesis in primates

Control of primate spermatogenesis is reviewed in terms of endogenous regulatory mechanisms and endocrine approaches to contraception and treatment of infertility. The role of gonadotropins and steroid hormones in maintaining spermatogenesis in primates is incompletely understood because A) hormonal interactions are complex, and B) most studies have used rodents rather than primates. Feedback control, interaction of LH and testosterone, the role of androgen, androgen in secondary sex organs, regulation of receptor proteins, roles of prolactin and growth hormone, and the breakdown and modification of the endocrine control mechanism are reviewed. The treatment of infertility with GnRH, gonadotropins, and androgen is discussed. Information is included on contraception research using the following methods: immunization against GnRH, use of GnRH analogs, immunization against gonadotropins, induced suppression of FSH secretion or action, and steroid suppression of spermatogenesis. The importance of studying testicular steroid metabolism in primates is stressed. Significant advances in the understanding of endocrine control of spermatogenesis have been made in recent years, but no primate species have been thoroughly studied. Variability between species in endocrine control mechanisms is an important factor in selecting primate models, and it is clear that such models can be valuable in the development of male contraceptives.     

On the flexibility and the dynamics of DNA

We describe and discuss the stability conditions of a naked double stranded DNA molecule starting from the evaluation of condensation or compactness fluctuation of this molecule embedded in pure water.     

Process dynamics, instrumentation and control

A total of 77 references pertaining to the subject were consulted to compose the present review. In addition to their years of publication (1981–1983), the references were selected primarily for their practicality and ability to provide experimental results and confirmation. First, a generalized model illustrating the biochemical reaction engineering considerations is presented. Here the knowledge of reactor and reaction kinetics is emphasized and the need for process instrumentation identified. Recent developments in key process sensors are then discussed in detail along with their utilities in various process situations. Finally, application of control principles and on-line computers to biochemical process operation is given a realistic evaluation by considering the process dynamics and instrumentation capabilities. Future challenges and opportunities from both the reaction engineering and system engineering points of view are carefully assessed. The most recent review relevant to the subject is that by Bull (1983).