Assessment of Attention in Preschoolers

In the past two decades, there has been an increased interest in the assessment and treatment of preschool children presenting with concerns about attention problems. This article reviews the research and clinical literature involving assessment of attention and related skills in the preschool years. While inattention among preschoolers is common, symptoms alone do not necessarily indicate a disorder, and most often represent a normal variation in typical preschool child development. Thus, accurate identification of ??disordered?? attention in preschoolers can be challenging, and development of appropriate, norm-referenced tests of attention for preschoolers is also difficult. The current review suggests that comprehensive assessment of attention and related functions in the preschool child should include thorough review of the child??s history, planned observations, and formal psychometric testing. The three primary methods of psychometric assessment that have been used to characterize attentional functioning in preschool children include performance-based tests, structured caregiver interviews, and rating scales (parent, teacher, and clinician). Among performance-based methods for measurement of attention in the preschool years, tests have been developed to assess sustained attention, selective (focused) attention, span of attention (encoding/manipulation), and (top-down) controlled attention??including freedom from distractibility and set shifting. Many of these tests remain experimental in nature, and review of published methods yields relatively few commercially available, nationally normed tests of attention for preschoolers, and an overall dearth of reliability and validity studies on the available measures.     

The study of autism as a distributed disorder

Past autism research has often been dedicated to tracing the causes of the disorder to a localized neurological abnormality, a single functional network, or a single cognitive-behavioral domain. In this review, I argue that autism is a "distributed disorder" on various levels of study (genetic, neuroanatomical, neurofunctional, behavioral). "Localizing" models are therefore not promising. The large array of potential genetic risk factors suggests that multiple (or all) emerging functional brain networks are affected during early development. This is supported by widespread growth abnormalities throughout the brain. Interactions during development between affected functional networks and atypical experiential effects (associated with atypical behavior) in children with autism further complicate the neurological bases of the disorder, resulting in an "exponentially distributed" profile. Promising approaches to a better characterization of neural endophenotypes in autism are provided by techniques investigating white matter and connectivity, such as MR spectroscopy, diffusion-tensor imaging (DTI), and functional connectivity MRI. According to a recent hypothesis, the autistic brain is generally characterized by "underconnectivity." However, not all findings are consistent with this view. The concepts and methodology of functional connectivity need to be refined and results need to be corroborated by anatomical studies (such as DTI tractography) before definitive conclusions can be drawn.     

抑郁症的脑功能异常:来自静息态功能磁共振成像的证据

静息态功能磁共振成像是指在静息状态下测量的BOLD信号,即受试者安静地躺在扫描仪中,不给受试者任何特定的任务,受试者也不用做任何反应,此时受试者的大脑活动处于自发状态。通过使用该技术可以为抑郁症发作的临床现象提供神经影像学依据,以期为将来抑郁症的治疗提供生物标记。因此,本文综述了大量抑郁症患者在静息态脑功能方面的差异研究,发现了单、双相抑郁症,首、复发抑郁症,早发性、晚发性抑郁症,难治、非难治性抑郁症等不同类型的抑郁症在包括局部一致性(Re Ho)和低频振幅(ALFF)在内的功能分化以及包括功能连接密度(FCD)、功能同伦(VMHC)、复杂网络(Complex Network)和ROI功能连接在内的功能整合两大指标的改变。     

Using immediate-early genes to map hippocampal subregional functions

Different functions have been suggested for the hippocampus and its subdivisions along both transversal and longitudinal axes. Expression of immediate-early genes (IEGs) has been used to map specific functions onto neuronal activity in different areas of the brain including the hippocampus (IEG imaging). Here we review IEG studies on hippocampal functional dissociations with a particular focus on the CA3 subregion. We first discuss the cellular functions of IEGs and the brain system interactions that govern their dynamic expression in hippocampal neurons to provide a more solid framework for interpreting the findings from IEG studies. We show the pitfalls and shortcomings of conventional IEG imaging studies and describe advanced methods using IEGs for imaging of neuronal activity or functional intervention. We review the current IEG evidence of hippocampal function, subregional-specific contribution to different stages of memory formation, systems consolidation, functional dissociation between memory and anxiety/behavioral inhibition along the septotemporal axis, and different neural network properties of hippocampal subregions. In total, IEG studies provide support for (1) the role of the hippocampus in spatial and contextual learning and memory, (2) its role in continuous encoding of ongoing experience, (3) septotemporal dissociations between memory and anxiety, and (4) a dynamic relationship between pattern separation and pattern completion in the CA3 subregion. In closing, we provide a framework for how cutting-edge IEG imaging and intervention techniques will likely contribute to better understanding of the specific functions of CA3 and other hippocampal subregions.     

The Role of Language Skill in Child Psychopathology: Implications for Intervention in the Early Years

In this narrative review, we suggest that children’s language skill should be targeted in clinical interventions for children with emotional and behavioral difficulties in the preschool years. We propose that language skill predicts childhood emotional and behavioral problems and this relationship may be mediated by children’s self-regulation and emotion understanding skills. In the first sections, we review recent high-quality longitudinal studies which together demonstrate that that children’s early language skill predicts: (1) emotional and behavioral problems, and this relationship is stronger than the reverse pattern; (2) self-regulation skill; this pattern may be stronger than the reverse pattern but moderated by child age. Findings also suggest that self-regulation skill mediates the relation between early language skill and children’s emotional and behavioral problems. There is insufficient evidence regarding the mediating role of emotion understanding. In subsequent sections, we review evidence demonstrating that: (1) particular kinds of developmentally targeted parent–child conversations play a vital role in the development of language skill, and (2) some current clinical interventions, directly or indirectly, have a beneficial impact on children’s vocabulary and narrative skills, but most approaches are ad hoc. Targeting language via parent–child conversation has the potential to improve the outcomes of current clinical interventions in the preschool years.     

Brain abnormalities in antisocial individuals: implications for the law

With the increasing popularity in the use of brain imaging on antisocial individuals, an increasing number of brain imaging studies have revealed structural and functional impairments in antisocial, psychopathic, and violent individuals. This review summarizes key findings from brain imaging studies on antisocial/aggressive behavior. Key regions commonly found to be impaired in antisocial populations include the prefrontal cortex (particularly orbitofrontal and dorsolateral prefrontal cortex), superior temporal gyrus, amygdala-hippocampal complex, and anterior cingulate cortex. Key functions of these regions are reviewed to provide a better understanding on how deficits in these regions may predispose to antisocial behavior. Objections to the use of imaging findings in a legal context are outlined, and alternative perspectives raised. It is argued that brain dysfunction is a risk factor for antisocial behavior and that it is likely that imaging will play an increasing (albeit limited) role in legal decision-making.     

Developmental neuroimaging of children using magnetic resonance techniques

Cognitive and motor development in children remain fascinating processes that are uniquely human. Progress has been made in recent years in elucidating the prenatal process of human brain development. In addition, much information exists regarding the behavioral aspects of postnatal human development. However, little is known about the relationship between anatomic postnatal central nervous system development and the accretion of functional milestones observed in children from the neonatal period through adolescence. Recently, powerful qualitative and quantitative magnetic resonance techniques have been developed that will permit detailed inquiry into the connection between the developing brain and the developing mind. In this review, first, the steps of prenatal and postnatal brain development are reviewed briefly. Subsequently, recent magnetic resonance imaging data related to human brain development during the fetal, neonatal, and later childhood periods are presented. Finally, functional magnetic resonance imaging (fMRI) is discussed. Specific examples of its usefulness are provided. Magnetic resonance imaging techniques such as quantitative MRI, volumetric MRI, diffusion tensor imaging, and functional magnetic resonance imaging (fMRI) when combined with neurologic and neuropsychologic evaluation, will provide new insights into the cognitive development of children. MRDD Research Reviews 6:68-80, 2000.     

The contribution of novel brain imaging techniques to understanding the neurobiology of mental retardation and developmental disabilities

Studying the biological mechanisms underlying mental retardation and developmental disabilities (MR/DD) is a very complex task. This is due to the wide heterogeneity of etiologies and pathways that lead to MR/DD. Breakthroughs in genetics and molecular biology and the development of sophisticated brain imaging techniques during the last decades have facilitated the emergence of a field called Behavioral Neurogenetics. Behavioral Neurogenetics focuses on studying genetic diseases with known etiologies that are manifested by unique cognitive and behavioral phenotypes. In this review, we describe the principles of magnetic resonance imaging (MRI) techniques, including structural MRI, functional MRI, and diffusion tensor imaging (DTI), and how they are implemented in the study of Williams (WS), velocardiofacial (VCFS), and fragile X (FXS) syndromes. From WS we learn that dorsal stream abnormalities can be associated with visuospatial deficits; VCFS is a model for exploring the molecular and brain pathways that lead to psychiatric disorders for which subjects with MR/DD are at increased risk; and finally, findings from multimodal imaging techniques show that aberrant frontal-striatal connections are implicated in the executive function and attentional deficits of subjects with FXS. By deciphering the molecular pathways and brain structure and function associated with cognitive deficits, we will gain a better understanding of the pathophysiology of MR/DD, which will eventually make possible more specific treatments for this population.     

Brain Networks in Schizophrenia

Schizophrenia—a severe psychiatric condition characterized by hallucinations, delusions, loss of initiative and cognitive function—is hypothesized to result from abnormal anatomical neural connectivity and a consequent decoupling of the brain’s integrative thought processes. The rise of in vivo neuroimaging techniques has refueled the formulation of dysconnectivity hypotheses, linking schizophrenia to abnormal structural and functional connectivity in the brain at both microscopic and macroscopic levels. Over the past few years, advances in high-field structural and functional neuroimaging techniques have made it increasingly feasible to reconstruct comprehensive maps of the macroscopic neural wiring system of the human brain, know as the connectome. In parallel, advances in network science and graph theory have improved our ability to study the spatial and topological organizational layout of such neural connectivity maps in detail. Combined, the field of neural connectomics has created a novel platform that provides a deeper understanding of the overall organization of brain wiring, its relation to healthy brain function and human cognition, and conversely, how brain disorders such as schizophrenia arise from abnormal brain network wiring and dynamics. In this review we discuss recent findings of connectomic studies in schizophrenia that examine how the disorder relates to disruptions of brain connectivity.     

默认网络的神经机制、功能假设及临床应用

认知神经科学的迅速发展使得研究者对大脑的功能有了深刻的认识。近些年来, 研究者对大脑在进行外在注意任务时产生的负激活有了更多的了解, 默认网络(Default Mode Network)的概念被提出, 并引起了很多神经科学家的关注, 关于默认网络的相关理论也已提出。当前综述对默认网络的研究历史, 概念理论, 个体和种系发展, 及其与疾病的关系以及临床应用等方面进行了概括总结。未来研究可从默认网络的个体发展, 种系差异, 与其他大脑网络(如注意网络, 视觉网络, 执行控制网络)的关系以及与具体疾病的关系等角度入手进行研究, 共同来探讨默认网络的神经机制。     

Assessment of Intelligence in the Preschool Period

Intelligence testing has a long and revered history in psychological measurement in childhood. Yet, the years between infancy and early childhood have been understudied with respect to emergent intellectual and cognitive functioning. Factor analytic models of intelligence that have demonstrated applicability when testing older children and adults often appear inadequate in the preschool period. As more is learned about brain development in typically developing children during these crucial years the distinctive relationships between neural system development and intellectual functioning are being revealed more completely. The aim of this paper was to provide a brief historical background as a foundation for discussion of intelligence testing, review what is known about the dynamic course of brain development during the preschool years, acknowledge limitations specific to intelligence testing in young children, and provide support for maintaining a comprehensive neuropsychological perspective that considers the wider range of variables that influence intellectual functioning in the preschool period.     

Cholinergic modulation of learning and memory in the human brain as detected with functional neuroimaging

The advent of neuroimaging methods such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) has provided investigators with a tool to study neuronal processes involved in cognitive functions in humans. Recent years have seen an increasing amount of studies which mapped higher cognitive functions to specific brain regions. These studies have had a great impact on our understanding of neuroanatomical correlates of learning and memory in the living human brain. Recently, advances were made to go beyond the use of fMRI as a pure cognitive brain mapping device. One of these advances includes the use of psychopharmacological approaches in conjunction with neuroimaging. The paper will introduce the combination of neuroimaging and psychopharmacology as a tool to study neurochemical modulation of human brain function. A review of imaging studies using cholinergic challenges in the context of explicit and implicit learning and memory paradigms is provided which show that cholinergic neurotransmission modulates task-related activity in sensory and frontal cortical brain areas.     

The cross-activation theory at 10

In 2001, Ramachandran and Hubbard introduced the cross-activation model of grapheme-colour synaesthesia. On the occasion of its 10-year anniversary, we review the evidence from experiments that have been conducted to test the model to assess how it has fared. We examine data from behavioural, functional magnetic resonance imaging (fMRI), anatomical studies (diffusion tensor imaging and voxel-based morphometry), and electroencephalography (EEG) and magnetoencephalography (MEG) studies of grapheme-colour synaesthesia. Although much of this evidence has supported the basic cross-activation hypothesis, our growing knowledge of the neural basis of synaesthesia, grapheme, and colour processing has necessitated two specific updates and modifications to the basic model: (1) our original model assumed that binding and parietal cortex functions were normal in synaesthesia; we now recognize that parietal cortex plays a key role in synaesthetic binding, as part of a two-stage model. (2) Based on MEG data we have recently collected demonstrating that synaesthetic responses begin within 140 ms of stimulus presentation, and an updated understanding of the neural mechanisms of reading as hierarchical feature extraction, we present a revised and updated version of the cross-activation model, the cascaded cross-tuning model. We then summarize data demonstrating that the cross-activation model may be extended to account for other forms of synaesthesia and discuss open questions about how learning, development, and cortical plasticity interact with genetic factors to lead to the full range of synaesthetic experiences. Finally, we outline a number of future directions needed to further test the cross-activation theory and to compare it with alternative theories.     

Shedding light on words and sentences: near-infrared spectroscopy in language research

Investigating the neuronal network underlying language processing may contribute to a better understanding of how the brain masters this complex cognitive function with surprising ease and how language is acquired at a fast pace in infancy. Modern neuroimaging methods permit to visualize the evolvement and the function of the language network. The present paper focuses on a specific methodology, functional near-infrared spectroscopy (fNIRS), providing an overview over studies on auditory language processing and acquisition. The methodology detects oxygenation changes elicited by functional activation of the cerebral cortex. The main advantages for research on auditory language processing and its development during infancy are an undemanding application, the lack of instrumental noise, and its potential to simultaneously register electrophysiological responses. Also it constitutes an innovative approach for studying developmental issues in infants and children. The review will focus on studies on word and sentence processing including research in infants and adults.     

The developmental cognitive neuroscience of functional connectivity

Developmental cognitive neuroscience is a rapidly growing field that examines the relationships between biological development and cognitive ability. In the past decade, there has been ongoing refinement of concepts and methodology related to the study of ‘functional connectivity’ among distributed brain regions believed to underlie cognition and behavioral control. Due to the recent availability of relatively easy-to-use tools for functional connectivity analysis, there has been a sharp upsurge of studies that seek to characterize normal and psychopathologically abnormal brain functional integration. However, relatively few studies have applied functional and effective connectivity analysis techniques to developmental cognitive neuroscience. Functional and effective connectivity analysis methods are ideally suited to advance our understanding of the neural substrates of cognitive development, particularly in understanding how and why changes in the functional ‘wiring’ of neural networks promotes optimal cognitive control throughout development. The purpose of this review is to summarize the central concepts, methods, and findings of functional integration neuroimaging research to discuss key questions in the field of developmental cognitive neuroscience. These ideas will be presented within a context that merges relevant concepts and proposals from different developmental theorists. The review will outline a few general predictions about likely relationships between typical ‘executive’ cognitive maturation and changes in brain network functional integration during adolescence. Although not exhaustive, this conceptual review also will showcase some of recent findings that have emerged to support these predictions.     

青少年创造性发展及其脑机制研究进展

青少年时期是创造性发展的关键阶段,探明青少年创造性发展规律及其神经机制对于培养和激发个体的创新潜能具有重要意义。本文综述了青少年创造性发展及其脑机制的研究进展,分别对青少年创造性思维发展趋势、影响因素及其相应的脑机制展开综述,并在此基础上进行了展望。总体而言,青少年时期创造性思维发展呈现出两个波峰(11~13岁,15~16岁)的发展趋势;青少年创造性发展受外部原生家庭教养方式和学校教师激励以及内部情绪动机和自我管理能力的影响较大;前额叶对青少年创造性发展具有重要作用,这可能与该脑区涉及执行控制功能有关。针对青少年创造性发展的教育干预以及大脑可塑性可能成为该领域的研究热点;而大样本纵向跟踪多模态脑影像数据库的建立可为相关研究提供重要支持。     

In vivo studies of brain development by magnetic resonance techniques

Understanding of the morphological development of the human brain has largely come from neuropathological studies obtained postmortem. Magnetic resonance (MR) techniques have recently allowed the provision of detailed structural, metabolic, and functional information in vivo on the human brain. These techniques have been utilized in studies from premature infants to adults and have provided invaluable data on the sequence of normal human brain development. This article will focus on MR techniques including conventional structural MR imaging techniques, quantitative morphometric MR techniques, diffusion weighted MR techniques, and MR spectroscopy. In order to understand the potential applications and limitations of MR techniques, relevant physical and biological principles for each of the MR techniques are first reviewed. This is followed by a review of the understanding of the sequence of normal brain development utilizing these techniques. MRDD Research Reviews 6:59-67, 2000.     

Language Development and Assessment in the Preschool Period

Most young children make significant progress in learning language during the first 4?years of life. Delays or differences in patterns of language acquisition are sensitive indicators of developmental problems. The dynamic, complex nature of language and the variability in the timing of its acquisition poses a number of challenges for the assessment of young children. This paper summarises the key developmental milestones of language development in the preschool years, providing a backdrop for understanding difficulties with language learning. Children with specific language impairment (SLI) are characterised illustrating the types of language difficulties they exhibit. Genetic evidence for language impairment suggests complex interactions among multiple genes of small effect. There are few consistent neurobiological abnormalities and currently there is no identified neurobiological signature for language difficulties. The assessment of young children??s language skills thus focuses on the evaluation of their performances in comparison to typically developing peers. Assessment of language abilities in preschool children should involve an evaluation of both expressive and receptive skills and should include an evaluation of more than one dimension of language. The use of a single measure of a language component, such as vocabulary, is considered inadequate for determining whether preschool children have typical language or language impairment. Available evidence supports the inclusion of measures of phonological short-term memory in the assessment of the language abilities of preschool children. Further study of genetic, neurobiological and early behavioural correlates of language impairments in preschool children is needed.     

Predictive coding explains binocular rivalry: an epistemological review

Binocular rivalry occurs when the eyes are presented with different stimuli and subjective perception alternates between them. Though recent years have seen a number of models of this phenomenon, the mechanisms behind binocular rivalry are still debated and we still lack a principled understanding of why a cognitive system such as the brain should exhibit this striking kind of behaviour. Furthermore, psychophysical and neurophysiological (single cell and imaging) studies of rivalry are not unequivocal and have proven difficult to reconcile within one framework. This review takes an epistemological approach to rivalry that considers the brain as engaged in probabilistic unconscious perceptual inference about the causes of its sensory input. We describe a simple empirical Bayesian framework, implemented with predictive coding, which seems capable of explaining binocular rivalry and reconciling many findings. The core of the explanation is that selection of one stimulus, and subsequent alternation between stimuli in rivalry occur when: (i) there is no single model or hypothesis about the causes in the environment that enjoys both high likelihood and high prior probability and (ii) when one stimulus dominates, the bottom-up, driving signal for that stimulus is explained away while, crucially, the bottom-up signal for the suppressed stimulus is not, and remains as an unexplained but explainable prediction error signal. This induces instability in perceptual dynamics that can give rise to perceptual transitions or alternations during rivalry.     

抑郁症的脑结构与功能异常:来自静息态下多模态脑影像的研究证据

传统单一模态、单一分析方法在揭示抑郁症脑机制上存在较多局限;而新近多种模态、多种分析方法的结合可在一定程度上较好地促进对抑郁症脑功能和结构的全面探索、挖掘,可以更加有效地运用和实施于早期辅助诊断、干预治疗当中。因此,本文首先简要介绍了多种模态下的脑影像指标及其分析技术,而后分别从结构及功能神经影像数据融合等方面,概述了抑郁症脑结构和功能的研究现状,发现抑郁症患者存在诸多脑区及相关环路结构及功能的异常。同时,通过对抑郁症多模态研究现状的梳理和总结,结合我们已有的相关前期研究工作,对未来抑郁症等情感障碍的进一步研究工作提出了一些思考和展望。