Critical periods and catastrophic interference effects in the development of self-organizing feature maps

The use of self-organizing feature maps (SOFM) in models of cognitive development has frequently been associated with explanations of critical or sensitive periods. By contrast, error-driven connectionist models of development have been linked with catastrophic interference between new knowledge and old knowledge. We introduce a set of simulations that systematically evaluate the conditions under which SOFMs demonstrate critical/sensitive periods in development versus those under which they display interference effects. We explored the relative contribution of network parameters (for example, whether learning rate and neighbourhood reduce across training), the representational resources available to the network, and the similarity between old and new knowledge in determining the functional plasticity of the maps. The SOFMs that achieved the best discrimination and topographic organization also exhibited sensitive periods in development while showing lower plasticity and hence limited interference. However, fast developing, coarser SOFMs also produced topologically organized representations, while permanently retaining their plasticity. We argue that the impact of map organization on behaviour must be interpreted in terms of the cognitive processes that the map is driving.     

Experience-dependent structural plasticity in the adult human brain

Contrary to assumptions that changes in brain networks are possible only during crucial periods of development, research in the past decade has supported the idea of a permanently plastic brain. Novel experience, altered afferent input due to environmental changes and learning new skills are now recognized as modulators of brain function and underlying neuroanatomic circuitry. Given findings in experiments with animals and the recent discovery of increases in gray and white matter in the adult human brain as a result of learning, the old concept of cognitive reserve, that is the ability to reinforce brain volume in crucial areas and thus provide a greater threshold for age-dependent deficits, has been reinforced. The challenge we face is to unravel the exact nature of the dynamic structural alterations and, ultimately, to be able to use this knowledge for disease management. Understanding normative changes in brain structure that occur as a result of environmental changes and demands is pivotal to understanding the characteristic ability of the brain to adapt.     

自我概念心理表征的文化神经科学研究

人类自我概念的心理表征在心理学和哲学有深入的研究, 跨文化心理学研究揭示了东西方文化自我概念的结构差异。近年来神经科学借助脑功能成像开始研究自我相关信息加工过程的神经机制, 并探讨是否存在文化特异的自我概念的认知神经表征。跨文化神经成像研究表明自我概念在知觉水平和人格特征表征方面都存在文化差异, 本文综述该领域的研究进展。跨文化和文化启动神经成像研究结果有助于我们理解自我概念表征文化差异背后的神经机制。这些研究推动了文化神经科学的发展。     

Sensitive periods in development: structural characteristics and causal interpretations

The presence or absence of a particular experience at a particular time in the life cycle may exert an extraordinary and dramatic influence over structure or function well beyond that point in development. Such sensitive periods are thought to be widespread in animal and in human neurobiology and psychology. A comprehensive treatment of the sensitive period needs minimally to include information about its structural characteristics as well as an interpretation of its causes, including why the sensitive period arises in terms of the natural history of the species and how the sensitive period is regulated in terms of physical, physiological, and psychological processes. This article provides a framework for research and theory concerning specific sensitive periods and the sensitive period generally conceived. The framework delimits four sets of parameters, which encompass 14 structural characteristics that define sensitive periods, and two levels of causal interpretation that guide research and theory into sensitive periods however they may be manifested.     

聋人早期手语经验对脑功能及结构的塑造作用

语言经验对脑功能和结构发展有重要的塑造作用。然而, 目前的相关证据主要来自对脑损伤导致的失语症病人的语言康复、第二语言学习以及针对成人读者进行的语言训练等方面的研究。幼儿时期的早期语言经验对脑结构与功能发展的影响更加重要, 但直接的研究证据却相当缺乏。本文提出一个研究设想, 拟综合使用多种脑成像技术, 系统探讨有早期手语经验和无早期手语经验的聋人个体在脑皮层语言功能的组织及脑结构发育的差异, 包括语言任务中大脑语言区的激活模式, 静息状态下脑功能联结的默认网络特征, 脑皮层灰质密度, 以及神经纤维束发育状况等, 揭示早期语言经验对大脑功能和结构发育的塑造作用。     

Development and the epigenome: the ‘synapse’ of gene–environment interplay

This paper argues that there is a revolution afoot in the developmental science of gene–environment interplay. We summarize, for an audience of developmental researchers and clinicians, how epigenetic processes – chromatin structural modifications that regulate gene expression without changing DNA sequences – may offer a strong, parsimonious account for the convergence of genetic and contextual variation in the genesis of adaptive and maladaptive development. Epigenetic processes may play a plausible explanatory role in understanding: divergent trajectories and sexual dimorphisms in brain development; statistical interactions between genes and environments; the biological embedding of early psychosocial adversities; the linkages of such adversities to disorders of mental health; the striking individual variation in the strength of those linkages; the molecular origins of critical and sensitive periods; and the transgenerational inheritance of risk and protection. Taken together, these arguments converge in a claim that epigenetic processes constitute a promising and illuminating point of connection – a ‘synapse’ – between genes and environments.     

Neuromodulation of behavioral and cognitive development across the life span

Among other mechanisms, behavioral and cognitive development entail, on the one hand, contextual scaffolding and, on the other hand, neuromodulation of adaptive neurocognitive representations across the life span. Key brain networks underlying cognition, emotion, and motivation are innervated by major transmitter systems (e.g., the catecholamines and acetylcholine). Thus, the maturation and senescence of neurotransmitter systems have direct implications for life span development. Recent progress in molecular genetics has opened new avenues for investigating neuromodulation of behavioral and cognitive development. This special section features 6 selected reviews of recent cognitive genetic evidence on the roles of dopamine and other transmitters in different domains of behavioral and cognitive development, ranging from temperament, executive control, and working memory to motivation and goal-directed behavior in different life periods.     

Environmental complexity and central nervous system development and function

Environmental restriction or deprivation early in development can induce social, cognitive, affective, and motor abnormalities similar to those associated with autism. Conversely, rearing animals in larger, more complex environments results in enhanced brain structure and function, including increased brain weight, dendritic branching, neurogenesis, gene expression, and improved learning and memory. Moreover, in animal models of CNS insult (e.g., gene deletion), a more complex environment has attenuated or prevented the sequelae of the insult. Of relevance is the prevention of seizures and attenuation of their neuropathological sequelae as a consequence of exposure to a more complex environment. Relatively little attention, however, has been given to the issue of sensitive periods associated with such effects, the relative importance of social versus inanimate stimulation, or the unique contribution of exercise. Our studies have examined the effects of environmental complexity on the development of the restricted, repetitive behavior commonly observed in individuals with autism. In this model, a more complex environment substantially attenuates the development of the spontaneous and persistent stereotypies observed in deer mice reared in standard laboratory cages. Our findings support a sensitive period for such effects and suggest that early enrichment may have persistent neuroprotective effects after the animal is returned to a standard cage environment. Attenuation or prevention of repetitive behavior by environmental complexity was associated with increased neuronal metabolic activity, increased dendritic spine density, and elevated neurotrophin (BDNF) levels in brain regions that are part of cortical-basal ganglia circuitry. These effects were not observed in limbic areas such as the hippocampus.     

Developing connections for affective regulation: age-related changes in emotional brain connectivity

The regulation of affective arousal is a critical aspect of children’s social and cognitive development. However, few studies have examined the brain mechanisms involved in the development of this aspect of “hot” executive functioning. This process has been conceptualized as involving prefrontal control of the amygdala. Here, using functional magnetic resonance imaging (fMRI), we investigated the brain mechanisms involved in the development of affective regulation in typically developing 5- to 11-year-olds and an adult comparison sample. Children and adults displayed differing patterns of increased anterior cingulate cortex and decreased amygdala activation during episodes in which emotion regulation was required. Specifically, amygdala activation increased in adults but decreased in children during recovery from a frustrating episode. In addition, we used effective connectivity analyses to investigate differential correlations between key emotional brain areas in response to the regulatory task demands. We found reliable increases in effective connectivity between the anterior cingulate cortex and the amygdala during periods of increased demand for emotion regulation. This effective connectivity increased with age.     

Neural correlates of perceptual narrowing in cross‐species face‐voice matching

Integrating the multisensory features of talking faces is critical to learning and extracting coherent meaning from social signals. While we know much about the development of these capacities at the behavioral level, we know very little about the underlying neural processes. One prominent behavioral milestone of these capacities is the perceptual narrowing of face–voice matching, whereby young infants match faces and voices across species, but older infants do not. In the present study, we provide neurophysiological evidence for developmental decline in cross‐species face–voice matching. We measured event‐related brain potentials (ERPs) while 4‐ and 8‐month‐old infants watched and listened to congruent and incongruent audio‐visual presentations of monkey vocalizations and humans mimicking monkey vocalizations. The ERP results indicated that younger infants distinguished between the congruent and the incongruent faces and voices regardless of species, whereas in older infants, the sensitivity to multisensory congruency was limited to the human face and voice. Furthermore, with development, visual and frontal brain processes and their functional connectivity became more sensitive to the congruence of human faces and voices relative to monkey faces and voices. Our data show the neural correlates of perceptual narrowing in face–voice matching and support the notion that postnatal experience with species identity is associated with neural changes in multisensory processing ( Lewkowicz & Ghazanfar, 2009 ).     

Developmental Pragmatics in Normal and Abnormal Children

We propose a critical review of current theories of developmental pragmatics. The underlying assumption is that such a theory ought to account for both normal and abnormal development. From a clinical point of view, we are concerned with the effects of brain damage on the emergence of pragmatic competence. In particular, the paper deals with direct speech acts, indirect speech acts, irony, and deceit in children with head injury, closed head injury, hydrocephalus, focal brain damage, and autism. Since no single theory covers systematically the emergence of pragmatic capacity in normal children, it is not surprising that we have not found a systematic account of deficits in the communicative performance of brain injured children. In our view, the challenge for a pragmatic theory is the determination of the normal developmental pattern within which different pragmatic phenomena may find a precise role. Such a framework of normal behavior would then permit the systematic study of abnormal pragmatic development.     

Neuronal substrates of relapse to cocaine-seeking behavior: role of prefrontal cortex

The return to drug seeking, even after prolonged periods of abstinence, is a defining feature of cocaine addiction. The neural circuitry underlying relapse has been identified in neuropharmacological studies of experimental animals, typically rats, and supported in brain imaging studies of human addicts. Although the nucleus accumbens (NAcc), which has long been implicated in goal-directed behavior, plays a critical role in this circuit, the prefrontal cortex (PFC) appears to process the events that directly trigger relapse: exposure to acute stress, cues previously associated with the drug, and the drug itself. In this paper, we review animal models of relapse and what they have revealed about the mechanisms underlying the involvement of the NAcc and PFC in cocaine-seeking behavior. We also present electrophysiological data from PFC illustrating how the hedonic, motor, motivational, and reinforcing effects of cocaine can be analyzed at the neuronal level. Our preliminary findings suggest a role for PFC in processing information related to cocaine seeking but not the hedonic effects of the drug. Further use of this recording technology can help dissect the functions of PFC and other components of the neural circuitry underlying relapse.     

Creative thinking and brain network development in schoolchildren

Fostering creative minds has always been a premise to ensure adaptation to new challenges of human civilization. While some alternative educational settings (i.e., Montessori) were shown to nurture creative skills, it is unknown how they impact underlying brain mechanisms across the school years. This study assessed creative thinking and resting-state functional connectivity via fMRI in 75 children (4–18 y.o.) enrolled either in Montessori or traditional schools. We found that pedagogy significantly influenced creative performance and underlying brain networks. Replicating past work, Montessori-schooled children showed higher scores on creative thinking tests. Using static functional connectivity analysis, we found that Montessori-schooled children showed decreased within-network functional connectivity of the salience network. Moreover, using dynamic functional connectivity, we found that traditionally-schooled children spent more time in a brain state characterized by high intra-default mode network connectivity. These findings suggest that pedagogy may influence brain networks relevant to creative thinking—particularly the default and salience networks. Further research is needed, like a longitudinal study, to verify these results given the implications for educational practitioners. A video abstract of this article can be viewed at https://www.youtube.com/watch?v=xWV_5o8wB5g .

Research Highlights

• Most executive jobs are prospected to be obsolete within several decades, so creative skills are seen as essential for the near future.
• School experience has been shown to play a role in creativity development, however, the underlying brain mechanisms remained under-investigated yet.
• Seventy-five 4–18 years-old children, from Montessori or traditional schools, performed a creativity task at the behavioral level, and a 6-min resting-state MR scan.
• We uniquely report preliminary evidence for the impact of pedagogy on functional brain networks.

     

Grand Unified Theories of the Brain Need Better Understanding of Behavior: The Two-Tiered Emergence of Function

Abstract

Over the last few decades, neuroscience and various associated disciples have expanded enormously in terms of output, tools, methods, concepts, and large-scale projects. In spite of these developments, the principles underlying brain function and behavior are yet only partially understood. We claim that brain functioning requires the elucidation of the rules associated with all possible task realizations, rather than targeting the activity underlying a specific realization. A first step in that direction was taken by approaches focusing on dynamical structures underlying task performances, as exemplified by coordination dynamics. Its theoretical foundation owes much to Haken’s synergetics, which provides a formalism through which the degrees of freedom associated with high-dimensional systems may be effectively reduced to one or a few functional variables in the vicinity of phase transitions. The recent theoretical development of structured flows on manifolds (SFM) allows the employment to a potentially broader range of applications. Here we expand the SFM framework and propose that the emergent two-tiered fast–slow dynamics may be a basic mathematical organization underlying the architecture of brain and behavior dynamics. Finally, along a few examples, we illustrate how this framework allows for the incorporation of notions cardinal to ecological psychology.     

Beyond family‐level adversities: Exploring the developmental timing of neighborhood disadvantage effects on the brain

A growing literature suggests that adversity is associated with later altered brain function, particularly within the corticolimbic system that supports emotion processing and salience detection (e.g., amygdala, prefrontal cortex [PFC]). Although neighborhood socioeconomic disadvantage has been shown to predict maladaptive behavioral outcomes, particularly for boys, most of the research linking adversity to corticolimbic function has focused on family‐level adversities. Moreover, although animal models and studies of normative brain development suggest that there may be sensitive periods during which adversity exerts stronger effects on corticolimbic development, little prospective evidence exists in humans. Using two low‐income samples of boys (n = 167; n = 77), Census‐derived neighborhood disadvantage during early childhood, but not adolescence, was uniquely associated with greater amygdala, but not PFC, reactivity to ambiguous neutral faces in adolescence and young adulthood. These associations remained after accounting for several family‐level adversities (e.g., low family income, harsh parenting), highlighting the independent and developmentally specific neural effects of the neighborhood context. Furthermore, in both samples, indicators measuring income and poverty status of neighbors were predictive of amygdala function, suggesting that neighborhood economic resources may be critical to brain development.     

Developmental science and the media. Early brain development

Media coverage of early brain development not only has focused public attention on early childhood but also has contributed to misunderstanding of developmental neuroscience research. This article critically summarizes current research in developmental neuroscience that is pertinent to the central claims of media accounts of early brain development, including (a) scientific understanding of formative early experiences, (b) whether critical periods are typical for brain development, (c) brain development as a lifelong process, (d) biological hazards to early brain growth, and (e) strengths and limits of current technology in developmental brain research. Recommendations are offered for strengthening the constructive contributions of research scientists and their professional organizations to the accurate and timely coverage of scientific issues in the media.     

Multimodal interactions in typically and atypically developing children: natural versus artificial environments

This review addresses the central role played by multimodal interactions in neurocognitive development. We first analyzed our studies of multimodal verbal and nonverbal cognition and emotional interactions within neuronal, that is, natural environments in typically developing children. We then tried to relate them to the topic of creating artificial environments using mobile toy robots to neurorehabilitate severely autistic children. By doing so, both neural/natural and artificial environments are considered as the basis of neuronal organization and reorganization. The common thread underlying the thinking behind this approach revolves around the brain’s intrinsic properties: neuroplasticity and the fact that the brain is neurodynamic. In our approach, neural organization and reorganization using natural or artificial environments aspires to bring computational perspectives into cognitive developmental neuroscience.     

Toward computational neuroconstructivism: a framework for developmental systems neuroscience

Brain development is underpinned by complex interactions between neural assemblies, driving structural and functional change. This neuroconstructivism (the notion that neural functions are shaped by these interactions) is core to some developmental theories. However, due to their complexity, understanding underlying developmental mechanisms is challenging. Elsewhere in neurobiology, a computational revolution has shown that mathematical models of hidden biological mechanisms can bridge observations with theory building. Can we build a similar computational framework yielding mechanistic insights for brain development? Here, we outline the conceptual and technical challenges of addressing this theory gap, and demonstrate that there is great potential in specifying brain development as mathematically defined processes operating within physical constraints. We provide examples, alongside broader ingredients needed, as the field explores computational explanations of system-wide development.     

Combined functional and causal connectivity analyses of language networks in children: a feasibility study

Instead of assessing activation in distinct brain regions, approaches to investigating the networks underlying distinct brain functions have come into the focus of neuroscience research. Here, we provide a completely data-driven framework for assessing functional and causal connectivity in functional magnetic resonance imaging (fMRI) data, employing Granger's causality. We investigate the networks underlying story processing in 17 healthy children (8f, 9m, 10.4+/-2.8 years, 6.5-15.4 years). Extensive functional connectivity exists between brain regions, including some not detected in standard random effects analyses. Causal connectivity analyses demonstrate a clear dominance of left-sided language regions for both forward and backward interactions with other network nodes. We believe our approach to be useful in helping to assess language networks in the normal or pathological setting; it may also aid in providing better starting estimates for the more hypothesis-driven approaches like structural equation or dynamic causal modeling.