scholarly journals Length of the Neurogenic Period—A Key Determinant for the Generation of Upper-Layer Neurons During Neocortex Development and Evolution

Author(s):  
Barbara K. Stepien ◽  
Samir Vaid ◽  
Wieland B. Huttner

The neocortex, a six-layer neuronal brain structure that arose during the evolution of, and is unique to, mammals, is the seat of higher order brain functions responsible for human cognitive abilities. Despite its recent evolutionary origin, it shows a striking variability in size and folding complexity even among closely related mammalian species. In most mammals, cortical neurogenesis occurs prenatally, and its length correlates with the length of gestation. The evolutionary expansion of the neocortex, notably in human, is associated with an increase in the number of neurons, particularly within its upper layers. Various mechanisms have been proposed and investigated to explain the evolutionary enlargement of the human neocortex, focussing in particular on changes pertaining to neural progenitor types and their division modes, driven in part by the emergence of human-specific genes with novel functions. These led to an amplification of the progenitor pool size, which affects the rate and timing of neuron production. In addition, in early theoretical studies, another mechanism of neocortex expansion was proposed—the lengthening of the neurogenic period. A critical role of neurogenic period length in determining neocortical neuron number was subsequently supported by mathematical modeling studies. Recently, we have provided experimental evidence in rodents directly supporting the mechanism of extending neurogenesis to specifically increase the number of upper-layer cortical neurons. Moreover, our study examined the relationship between cortical neurogenesis and gestation, linking the extension of the neurogenic period to the maternal environment. As the exact nature of factors promoting neurogenic period prolongation, as well as the generalization of this mechanism for evolutionary distinct lineages, remain elusive, the directions for future studies are outlined and discussed.

Author(s):  
Rollin McCraty

As pervasive and vital as they are in human experience, emotions have long remained an enigma to science. This chapter explores recent scientific advances that clarify central controversies in the study of emotion, including the relationship between intellect and emotion and the historical debate on the source of emotional experience. Particular attention is given to the intriguing body of research illuminating the critical role of ascending input from the body to the brain in the generation and perception of emotions. This discussion culminates in the presentation of a new, systems-oriented model of emotion in which the brain functions as a complex pattern-matching system, continually processing input from both the external and internal environments. From this perspective, it is shown that the heart is a key component of the emotional system, thus providing a physiological basis for the long-acknowledged link between the heart and our emotional life.


2020 ◽  
Vol 375 (1803) ◽  
pp. 20190495 ◽  
Author(s):  
Natalie Uomini ◽  
Joanna Fairlie ◽  
Russell D. Gray ◽  
Michael Griesser

Traditional attempts to understand the evolution of human cognition compare humans with other primates. This research showed that relative brain size covaries with cognitive skills, while adaptations that buffer the developmental and energetic costs of large brains (e.g. allomaternal care), and ecological or social benefits of cognitive abilities, are critical for their evolution. To understand the drivers of cognitive adaptations, it is profitable to consider distant lineages with convergently evolved cognitions. Here, we examine the facilitators of cognitive evolution in corvid birds, where some species display cultural learning, with an emphasis on family life. We propose that extended parenting (protracted parent–offspring association) is pivotal in the evolution of cognition: it combines critical life-history, social and ecological conditions allowing for the development and maintenance of cognitive skillsets that confer fitness benefits to individuals. This novel hypothesis complements the extended childhood idea by considering the parents' role in juvenile development. Using phylogenetic comparative analyses, we show that corvids have larger body sizes, longer development times, extended parenting and larger relative brain sizes than other passerines. Case studies from two corvid species with different ecologies and social systems highlight the critical role of life-history features on juveniles’ cognitive development: extended parenting provides a safe haven, access to tolerant role models, reliable learning opportunities and food, resulting in higher survival. The benefits of extended juvenile learning periods, over evolutionary time, lead to selection for expanded cognitive skillsets. Similarly, in our ancestors, cooperative breeding and increased group sizes facilitated learning and teaching. Our analyses highlight the critical role of life-history, ecological and social factors that underlie both extended parenting and expanded cognitive skillsets. This article is part of the theme issue ‘Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals’.


2021 ◽  
pp. 082957352110347
Author(s):  
Luis Francisco Vargas-Madriz ◽  
Chiaki Konishi

Canada’s high school graduation rates are still low when compared to other members of the OECD. Previous studies have found academic involvement is associated with positive trajectories toward graduation, that social support promotes student engagement, and that school belonging could mediate this relationship. Still, little is known about the specificity of such mediation, especially in Québec. Therefore, this study examined the role of belonging as mediator of the relationship between social support and academic involvement. Participants ( N = 238) were high-school students from the Greater Montréal Area. All variables were measured by the School-Climate Questionnaire. Results from hierarchical multiple regressions indicated parental support had a direct relationship, whereas peer and teacher support had a mediated relationship by school belonging with academic involvement. Results highlight the critical role of school belonging in promoting academic involvement in relation to social support.


2016 ◽  
Vol 10 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Man Zhang ◽  
Qian Gao ◽  
Jane V. Wheeler ◽  
Jungsook Kwon

Purpose – This paper aims to investigate the role of Sun Tzu’s significant strategies on the relationship between the institutional environment and international performance of Chinese born global firms, a type of small- and medium-sized enterprise (SME) characterized by the company’s limited resources and its early efforts to internationalize. Design/methodology/approach – The methodology is based on a multi-case analysis of interviews conducted with four chosen born global firms, coupled with public database and Web site searches. Through the use of qualitative methods, propositions were developed. Findings – This paper provides insights regarding how the institutional environment, both formal and informal, has a strong positive relationship with born global firm’s international performance. Moreover, Sun Tzu’s significant strategies play a critical role in the internationalization process of born global firms in emerging markets. Originality/value – Although existing studies discuss the application of Eastern philosophical strategies adopted by firms in emerging markets, to the best of our knowledge, this is one of the earliest studies which evaluates the moderation effect of Sun Tzu’s significant strategies on the relationship between institutional environment and business performance. The paper contributes to scholarly discourse on the influencing factors of born global firm’s internationalization process. It also has practical relevance to international entrepreneurs and SMEs from emerging markets.


Author(s):  
Muhammad Abbas ◽  
Asif Ali ◽  
Muhammad Ahsan Khalid

The paper investigates the critical role of organisational commitment between leadership style and employees’ performance. Generally, the relationship between leadership style and the organisational performance has been discussed widely but ignoring the employees’ performance. It has been accepted that the organisational commitment leads to higher employee performance but the existing literature has not focused much on this view. A conceptual model has been developed which links the constructs together.The model reveals the missing link of organisational commitment between leadership style and employees’ performance. The sample of 242 was collected from the managers and employees of manufacturing and service organisations. The finding confirmed that organisational commitment acted as a mediator between the leadership style and employees’ performance.  


2021 ◽  
Vol 49 (7) ◽  
pp. 1-15
Author(s):  
Seungju Hyun ◽  
Xyle Ku

Although the relationship between grandiose and vulnerable narcissism and psychological health is widely accepted, little is known about whether and how coping strategies explain this relationship. We examined the mediating role of proactive coping in this relationship, with a sample of 280 participants from five colleges in Korea. We used four parallel multiple mediation models, and controlled for the indirect effects of coping flexibility, self-esteem, and covariates (age and gender). Results show that grandiose narcissism predicted higher life satisfaction and lower perceived stress, whereas vulnerable narcissism exhibited the opposite pattern, and all of these relationships were mediated by proactive coping. Overall, our results highlight the critical role of proactive coping in the prediction of psychological health among narcissists.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  

Purpose The authors wanted to find out the most important mechanisms for encouraging innovative behavior in the Indian manufacturing sector. Design/methodology/approach The researchers collected data from Indian manufacturing organizations. They distributed questionnaires and received 288 complete ones. Items measured critical concepts. For OJ one example was “I have been fairly rewarded for the effort I put forth”. For KS, one sample was, “When I have learned something new, I tell my colleagues about it” and, “When they have learned something new, my colleagues tell me about it”. Meanwhile, IB was measured using items such as “I generate original solutions for problems”. Findings It highlighted the pivotal role of OJ in bolstering employees’ IB. When companies treat employees fairly, it encourages positive social interactions that lead to perceptions of supportiveness and trustworthiness. Employees reciprocate these sentiments with positive behavior. The study also showed the positive predictive influence of KS on IB. Finally, the results showed that the relationship between OJ and IB is complex, but KS is a pivotal mediator. Promotion of OJ, KS and IM is “vital” to spark innovation. Originality/value The authors felt their most important finding was to highlight the critical role of the underlying mechanism of KS, which is where individuals exchange implicit and explicit knowledge to create new knowledge. In addition, previous researchers have looked at the role of organizational justice in encouraging innovative behavior, but evidence from non-Western countries is scarce.


Author(s):  
Christina Phillips

This chapter introduces the topic of religion and literature, theorises the novel as a secular genre, and develops a concept of religion as the other in the Arabic novel. It begins with a discussion of the relationship between religion and literature, identifying imagination, metaphorical language and mythos as areas of overlap, before turning to the question of religion and the Arabic novel as a modern form which eschews faith and dogma but is nevertheless packed with religious themes, images, characters, language and intertextuality. This is accounted for by the form’s secularism, which is theorised in terms of Charles Taylor’s conditions of belief. Literary secularism is not static and stable however, thus religion emerges as the other in the Egyptian novel, with all the ambivalence which alterity characteristically entails. This religious other calls into question postcolonial studies’ over-valorisation of the East/West binary insofar as it has obscured the critical role of religion in Arab postcolonial literature and identity.


2019 ◽  
Vol 48 (2) ◽  
pp. 207-226 ◽  
Author(s):  
Choukri Menidjel ◽  
Abderrezzak Benhabib ◽  
Anil Bilgihan ◽  
Melih Madanoglu

Purpose Product category involvement and relationship proneness are crucial in explaining relationship outcomes. Nevertheless, the authors know little about their roles in the formation of loyalty, especially in the retail industry. Individual consumer traits and preferences are likely to play a critical role in the success of relationship marketing. Yet, relationship marketing studies have fallen short of considering such individual differences. The purpose of this paper is to examine the mediating effects of product category involvement and relationship proneness on the relationship between satisfaction and loyalty in retail clothing stores. Design/methodology/approach Data were obtained using a survey of 220 consumers. Partial least squares structural equation modeling was employed to test the proposed theoretical model. Findings The results show that satisfaction significantly affects product category involvement and relationship proneness, which, in turn, significantly affect purchase intention and word-of-mouth (WOM). The results also show that product category involvement and relationship proneness partially mediate the impact of satisfaction on purchase intention and WOM. Research limitations/implications Product category involvement and relationship proneness play a critical role in explaining the satisfaction–loyalty link. Future research could consider the role of potential moderating variables. Practical implications Retail managers should not only focus on improving customer satisfaction to achieve customer loyalty, but should also consider the importance of product category involvement and relationship proneness, and their role in the formation of customer loyalty both in traditional and online environments. Originality/value To the best of the authors’ knowledge, this study is the first to explore the mediating effects of product category involvement and relationship proneness on the relationship between satisfaction, purchase intention and WOM in the retail industry.


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