1-20 of 44 Results

  • Keywords: brain x
Clear all

Article

Development of the brain in the first 3 years of life is genetically programmed but occurs in response to environmental stimuli. The brain is organized “from the bottom up,” that is, from simpler to more complex structures and functions, so the experiences and environment that shape early development have consequences that reach far into the future. This entry describes the ontogeny and processes of fetal and infant brain development, as well as major risks to early brain development (during pregnancy and after birth), with emphasis on the factors seen in social-work practice. Neuroscience research is changing social work practice, and understanding early brain development and the contributors to poor development is critical for social workers in medical, mental health, child welfare, and other practice settings.

Article

Michael J. Valenzuela

Cognitive reserve refers to the many ways that neural, cognitive, and psychosocial processes can adapt and change in response to brain aging, damage, or disease, with the overarching effect of preserving cognitive function. Cognitive reserve therefore helps to explain why cognitive abilities in late life vary as dramatically as they do, and why some individuals are brittle to degenerative pathology and others exceptionally resilient. Historically, the term has evolved and at times suffered from vague, circular, and even competing notions. Fortunately, a recent broad consensus process has developed working definitions that resolve many of these issues, and here the evidence is presented in the form of a suggested Framework: Contributors to cognitive reserve, which include environmental exposures that demand new learning and intellectual challenge, genetic factors that remain largely unknown, and putative G × E interactions; mechanisms of cognitive reserve that can be studied at the biological, cognitive, or psychosocial level, with a common theme of plasticity, flexibility, and compensability; and the clinical outcome of (enriched) cognitive reserve that can be summarized as a compression of cognitive morbidity, a relative protection from incident dementia but increased rate of progression and mortality after diagnosis. Cognitive reserve therefore has great potential to address the global challenge of aging societies, yet for this potential to be realized a renewed scientific, clinical, and societal focus will be required.

Article

A brain-based approach can provide a framework for intelligence, for integration of biology and cognitive processes that have direct implications for education and brain plasticity. Intelligence is reframed here as a selective cluster of different cognitive processes often localized in broad divisions of the brain. Theories and systems that have guided investigation into the brain mechanisms for cognitive processes are reviewed. The focus is on education and cultural disadvantage, delineating changes in the brain due to learning and its dysfunction. Selected programs for enhancement of neurocognitive abilities are presented. Neuronal changes appear to occur as a consequence of learning throughout life. A brain-based approach not only relates to how intelligence works, but also opens the door to understanding the mind and hence consciousness. One may say that the mind is not an eclectic collection of intellectual functions of the brain. Rather, the ultimate goal of intelligence is to form a better view of self that gives meaning to an individual’s existence.

Article

The most dynamic postnatal brain development takes place during human infancy. Decades of histological studies have identified strong spatial and functional maturation gradients in human brain gray and white matter. The improvements in noninvasive imaging techniques, especially magnetic resonance imaging, magnetic resonance spectroscopy, electroencephalography, magnetoencephalography, positron emission tomography, and near-infrared spectroscopy, have provided unprecedented opportunities to quantify and map the early developmental changes at whole brain and regional levels. Unique to infant brain imaging, tailored infant image acquisition and analysis methods—such as motion correction, high-resolution imaging, optimization of imaging parameters for smaller and immature brain, age-specific brain atlas and parcellation scheme, age-specific white matter tractography, functional connectivity analysis given incomplete brain networks, and advanced gray and white matter segmentation for infant brains should be taken into consideration. Delineating functional, physiological, and structural changes of the infant brain through imaging provides insights into the complicated processes of both typical development and the neuropathological mechanisms underlying various brain disorders with early onset in infancy, such as autistic spectrum disorder. Identification of imaging biomarkers of neurodevelopmental disorders during infancy by leveraging techniques such as machine learning may offer a valuable time window for early intervention.

Article

The glucocorticoid hormones cortisol and corticosterone coordinate circadian events and are master regulators of the stress response. These actions of the glucocorticoids are mediated by mineralocorticoid receptors (NR3C2, or MRs) and glucocorticoid receptors (NR3C1, or GRs). MRs bind the natural glucocorticoids cortisol and corticosterone with a 10-fold higher affinity than GRs. The glucocorticoids are inactivated only in the nucleus tractus solitarii (NTS), rendering the NTS-localized MRs aldosterone-selective and involved in regulation of salt appetite. Everywhere else in the brain MRs are glucocorticoid-preferring. MR and GR are transcription factors involved in gene regulation but recently were also found to mediate rapid non-genomic actions. Genomic MRs, with a predominant localization in limbic circuits, are important for the threshold and sensitivity of the stress response system. Non-genomic MRs promote appraisal processes, memory retrieval, and selection of coping style. Activation of GRs makes energy substrates available and dampens initial defense reactions. In the brain, GR activation enhances appetitive- and fear-motivated behavior and promotes memory storage of the selected coping style in preparation of the future. Thus, MRs and GRs complement each other in glucocorticoid control of the initiation and termination of the stress response, suggesting that the balance in MR- and GR-mediated actions is crucial for homeostasis and health.

Article

Primate societies are unusually complex compared to those of other animals, and the need to manage such complexity is the main explanation for the fact that primates have unusually large brains. Primate sociality is based on bonded relationships that underpin coalitions, which in turn are designed to buffer individuals against the social stresses of living in large, stable groups. This is reflected in a correlation between social group size and neocortex size in primates (but not other species of animals), commonly known as the social brain hypothesis, although this relationship itself is the outcome of an underlying relationship between brain size and behavioral complexity. The relationship between brain size and group size is mediated, in humans at least, by mentalizing skills. Neuropsychologically, these are all associated with the size of units within the theory of mind network (linking prefrontal cortex and temporal lobe units). In addition, primate sociality involves a dual-process mechanism whereby the endorphin system provides a psychopharmacological platform off which the cognitive component is then built. This article considers the implications of these findings for the evolution of human cognition over the course of hominin evolution.

Article

Megan S. Barker, Emily C. Gibson, and Gail A. Robinson

The term “acquired brain injury” refers to any type of brain damage that occurs after birth. Two main types of acquired brain injury are stroke and traumatic brain injury (TBI). A stroke occurs when there is a blockage or bleed in the vascular system of the brain, while a TBI results from an external force to the head. Older adults are at a higher risk of both stroke and TBI; thus, overall incidence is increasing as the proportion of older adults in the population is growing. Stroke and TBI result in immediate and long-term cognitive changes. Impairments in the domains of language, attention, memory, executive functions, perception, and social cognition have been documented following stroke and TBI. However, strokes tend to cause focal or selective cognitive disorders, while cognitive deficits following TBI are widespread and can be generalized. Individuals who have suffered a stroke or TBI may also experience psychosocial changes; for example, symptoms of depression and anxiety are common. Functional outcomes, including independence in activities, are varied and are associated with a range of factors including age, injury severity, cognitive disorders, and psychosocial factors. To achieve optimal outcomes for individuals following stroke and TBI, and to reduce the impact of the injury on everyday functioning, a multidisciplinary rehabilitation process is recommended.

Article

Tipu Aziz and Holly Roy

Deep brain stimulation (DBS) is a neurosurgical technology that allows the manipulation of activity within specific brain regions through delivery of electrical stimulation via implanted electrodes. The growth of DBS has led to research around the development of novel interventions for a wide range of neurological and neuropsychiatric conditions, including Parkinson’s disease, dystonia, chronic pain, Tourette’s syndrome, treatment-resistant depression, anorexia nervosa, and Alzheimer’s disease. Some of these treatment approaches have a high level of efficacy as well as an established place in the clinical armamentarium for the diseases in question, such as DBS for movement disorders, including Parkinson’s disease. Other interventions are at a more developmental stage, such as DBS for depression and Alzheimer’s disease. Success both in clinical aspects of DBS and new innovations depends on a close-knit multidisciplinary team incorporating experts in the underlying condition (often neurologists and psychiatrists); neurosurgeons; nurse specialists, who may be involved in device programming and other aspects of patient care; and researchers including neuroscientists, imaging specialists, engineers, and signal analysts. Directly linked to the growth of DBS as a specialty is allied research around neural signals analysis and device development, which feed directly back into further clinical progress. The close links between clinical DBS and basic and translational research make it an exciting and fast-moving area of neuroscience.

Article

Ian Q. Whishaw and Megan Sholomiski

A brain lesion is an area of damage, injury, or abnormal change to a part of the brain. Brain lesions may be caused by head injury, disease, surgery, or congenital disorders, and they are classified by the cause, extent, and locus of injury. Lesions cause many behavioral symptoms. Symptom severity generally corresponds to the region and extent of damaged brain. Thus, behavior is often a reliable indicator of the type and extent of a lesion. Observations of patients suffering brain lesions were first recorded in detail in the 18th century, and lesion studies continue to shape modern neuroscience and to give insight into the functions of brain regions. Recovery, defined as any return of lost behavioral or cognitive function, depends on the age, sex, genetics, and lifestyle of patients, and recovery may be predicted by the cause of injury. Most recovery occurs within the first 6 to 9 months after injury and likely involves a combination of compensatory behaviors and physiological changes in the brain. Children often recover some function after brain lesions better than adults, though both children and adults experience residual deficits. Brain lesion survival rates are improved by better diagnostic tools and treatments. Therapeutic interventions and treatments for brain lesions include surgery, pharmaceuticals, transplants, and temperature regulation, each with varying degrees of success. Research in treating brain lesions is progressing, but in principle a cure will only be complete when brain lesions are replaced with healthy tissue.

Article

Aderanti Adepoju

Intraregional migration of cross-border workers, unskilled and temporary contract workers, undocumented migrants, highly skilled professionals, and refugees characterize the migration landscape in Africa and is reflected in distinctive and changing configurations in the different subregions: labor migration in the west and central areas, movement of refugees in the eastern and southern areas, and migration of skilled professionals from west and east to southern Africa. Migrants and refugees in Africa share a number of common features: both are caused in large part by a set of interrelated factors—conflicts, underdevelopment, poor governance, and economic and social deprivation—and movements are confined largely to the continent. Youth unemployment, a major trigger for irregular migration, together with emigration of skilled professionals, pose serious challenges for many countries; remittances from the diaspora, though a lifeline for poor families left behind, do not compensate for the loss of skills. The refugee situation is highly dynamic and fluid. The sheer numbers of refugees in Africa, their composition, and the challenges they face and the limited success obtained thus far in the search for a permanent solution require sustained efforts in what is regarded an African problem requiring essentially an African solution.

Article

Jessica M. Black

Although it was once widely held that development through toddlerhood was the only significant time of tremendous brain growth, findings from neuroscience have identified adolescence as a second significant period of brain-based changes. Profound modification of brain structure, function, and connectivity, paired with heightened sensitivity to environment, places adolescence both as a heightened period of risk and importantly as a time of tremendous opportunity. These findings are of key relevance for social-work policy and practice, for they speak to the ways in which the adolescent brain both is vulnerable to adverse conditions and remains responsive to positive environmental input such as interventions that support recovery and resilience.

Article

Jamie Ward

People with synesthesia have unusual sensory experiences whereby one stimulus elicits another: Words may evoke tastes, numbers evoke colors, and so on. The eliciting stimulus is called the inducer, whereas the synesthetic experience, which is normally percept-like in quality, is referred to as the concurrent. Synesthetic experiences use some of the same neural substrates as “real” perception. The associations are influenced by cross-modal correspondences between the senses (e.g., high pitch being bright or light) and regularities in one’s own environment. Synesthesia comes in many varieties, but these likely stem from a common cause (because different varieties tend to co-occur together). This is normally explained in terms of an atypical neurodevelopmental cascade from genetic differences that affect brain development and give rise to an atypical profile of behaviors (of which synesthesia is one). People with synesthesia not only have unusual sensory experiences—this being the trait that defines them—but also present with a distinctive cognitive profile (affecting memory, imagery, perception) that has impacts on their life choices (e.g., occupation) and may predispose selectively toward certain clinical vulnerabilities.

Article

Janette Atkinson

Human visual development is a complex dynamic psychological/neurobiological process, being part of the developing systems for cognition, action, and attention. This article reviews current knowledge and methods of study of human visual development in infancy and childhood, in relation to typical early visual brain development, and how it can change in developmental disorders, both acquired (e.g., related to at-risk births) and genetic disorders. The newborn infant starts life with a functioning subcortical visual system which controls newborn orienting to nearby high contrast objects and faces. Although visual cortex may be active from birth, its characteristic stimulus selectivity and control of visual responses is generally seen to emerge around six to twelve weeks after birth. By age six months the infant has adequate acuity and contrast sensitivity in nearby space, and operating cortical mechanisms for discriminating colors, shapes, faces, movement, stereo depth, and distance of objects, as well as the ability to focus and shift attention between objects of interest. This may include both feedforward and feedback pathways between cortical areas and between cortical and subcortical areas. Two cortical streams start to develop and become interlinked, the dorsal stream underpinning motion, spatial perception and actions, and the ventral stream for recognition of objects and faces. The neural systems developing control and planning of actions include those for directed eye movements, reaching and grasping, and the beginnings of locomotion, with these action systems being integrated into the other developing subcortical and cortical visual networks by one year of age. Analysis of global static form (pattern) and global motion processing allows the development of dorsal and ventral streams to be monitored from infancy through childhood. The development of attention, visuomotor control and spatial cognition in the first years show aspects of function related to the developing dorsal stream, and their integration with the ventral stream. The milestones of typical visual development can be used to characterize visual and visuo-cognitive disorders early in life, such as in infants with perinatal brain injuries and those born very prematurely. The concept of “dorsal stream vulnerability” is outlined. It was initially based on deficits in global motion sensitivity relative to static form sensitivity, but can be extended to the planning and execution of visuomotor actions and problems of attention, together with visuospatial and numerical cognition. These problems are found in the phenotype of children with both genetic developmental disorders (e.g., Williams syndrome, autism, fragile-X, and dyslexia), and in acquired developmental disorders related to very preterm birth, or in children with abnormal visual input such as congenital cataract, refractive errors, or amblyopia. However, there are subtle differences in the manifestation of these disorders which may also vary considerably across individuals. Development in these clinical conditions illustrates the early, but limited, plasticity of visual brain mechanisms, and provides a challenge for the future in designing successful intervention and treatment.

Article

Cedric Boeckx and Pedro Tiago Martins

All humans can acquire at least one natural language. Biolinguistics is the name given to the interdisciplinary enterprise that aims to unveil the biological bases of this unique capacity.

Article

The majority of anxiety disorders emerge during childhood and adolescence, a developmental period characterized by dynamic changes in frontolimbic circuitry. Frontolimbic circuitry plays a key role in fear learning and has been a focus of recent efforts to understand the neurobiological correlates of anxiety disorders across development. Although less is known about the neurobiological underpinnings of anxiety disorders in youth than in adults, studies of pediatric anxiety have revealed alterations in both the structure and function of frontolimbic circuitry. The amygdala, prefrontal cortex (PFC), anterior cingulate cortex (ACC), and hippocampus contribute to fear conditioning and extinction, and interactions between these regions have been implicated in anxiety during development. Specifically, children and adolescents with anxiety disorders show altered amygdala volumes and exhibit heightened amygdala activation in response to neutral and fearful stimuli, with the magnitude of signal change in amygdala reactivity corresponding to the severity of symptomatology. Abnormalities in the PFC and ACC and their connections with the amygdala may reflect weakened top-down control or compensatory efforts to regulate heightened amygdala reactivity associated with anxiety. Taken together, alterations in frontolimbic connectivity are likely to play a central role in the etiology and maintenance of anxiety disorders. Future studies should aim to translate the emerging understanding of the neurobiological bases of pediatric anxiety disorders to optimize clinical interventions for youth.

Article

The Motor Theory of Speech Perception is a proposed explanation of the fundamental relationship between the way speech is produced and the way it is perceived. Associated primarily with the work of Liberman and colleagues, it posited the active participation of the motor system in the perception of speech. Early versions of the theory contained elements that later proved untenable, such as the expectation that the neural commands to the muscles (as seen in electromyography) would be more invariant than the acoustics. Support drawn from categorical perception (in which discrimination is quite poor within linguistic categories but excellent across boundaries) was called into question by studies showing means of improving within-category discrimination and finding similar results for nonspeech sounds and for animals perceiving speech. Evidence for motor involvement in perceptual processes nonetheless continued to accrue, and related motor theories have been proposed. Neurological and neuroimaging results have yielded a great deal of evidence consistent with variants of the theory, but they highlight the issue that there is no single “motor system,” and so different components appear in different contexts. Assigning the appropriate amount of effort to the various systems that interact to result in the perception of speech is an ongoing process, but it is clear that some of the systems will reflect the motor control of speech.

Article

Pedro Martínez, Volker Hartenstein, and Simon G. Sprecher

The emergence and diversification of bilateral animals are among the most important transitions in the history of life on our planet. A proper understanding of the evolutionary process will derive from answering such key questions as, how did complex body plans arise in evolutionary time, and how are complex body plans “encoded” in the genome? the first step is focusing on the earliest stages in bilaterian evolution, probing the most elusive organization of the genomes and microscopic anatomy in basally branching taxa, which are currently assembled in a clade named Xenacoelomorpha. This enigmatic phylum is composed of three major taxa: acoel flatworms, nemertodermatids, and xenoturbellids. Interestingly, the constituent species of this clade have an enormously varied set of morphologies; not just the obvious external features but also their tissues present a high degree of constructional variation. This interesting diversity of morphologies (a clear example being the nervous system, with animals showing different degrees of compaction) provides a unique system in which to address outstanding questions regarding the parallel evolution of genomes and the many morphological characters encoded by them. A systematic exploration of the anatomy of members of these three taxa, employing immunohistochemistry, in situ hybridization, and high-throughput transmission electron microscopy, will provide the reference framework necessary to understand the changing roles of genes and gene networks during the evolution of xenacoelomorph morphologies and, in particular, of their nervous systems.

Article

Jessica M. Black

Scientific findings from social sciences, neurobiology, endocrinology, and immunology highlight the adaptive benefits of positive emotion and activity to both mental and physical health. Positive activity, such as engagement with music and exercise, can also contribute to favorable health outcomes. This article reviews scientific evidence of the adaptive benefits of positive emotion and activity throughout the life course, with examples drawn from the fetal environment through late adulthood. Specifically, the text weaves together theory and empirical findings from an interdisciplinary literature to describe how positive emotion and activity help to build important cognitive, social, and physical resources throughout the life course.

Article

Susan Edwards and Christos Salis

Aphasia is an acquired language disorder subsequent to brain damage in the left hemisphere. It is characterized by diminished abilities to produce and understand both spoken and written language compared with the speaker’s presumed ability pre-cerebral damage. The type and severity of the aphasia depends not only on the location and extent of the cerebral damage but also the effect the lesion has on connecting areas of the brain. Type and severity of aphasia is diagnosed in comparison with assumed normal adult language. Language changes associated with normal aging are not classed as aphasia. The diagnosis and assessment of aphasia in children, which is unusual, takes account of age norms. The most common cause of aphasia is a cerebral vascular accident (CVA) commonly referred to as a stroke, but brain damage following traumatic head injury such as road accidents or gunshot wounds can also cause aphasia. Aphasia following such traumatic events is non-progressive in contrast to aphasia arising from brain tumor, some types of infection, or language disturbances in progressive conditions such as Alzheimer’s disease, where the language disturbance increases as the disease progresses. The diagnosis of primary progressive aphasia (as opposed to non-progressive aphasia, the main focus of this article) is based on the following inclusion and exclusion criteria by M. Marsel Mesulam, in 2001. Inclusion criteria are as follows: Difficulty with language that interferes with activities of daily living and aphasia is the most prominent symptom. Exclusion criteria are as follows: Other non-degenerative disease or medical disorder, psychiatric diagnosis, episodic memory, visual memory, and visuo-perceptual impairment, and, finally, initial behavioral disturbance. Aphasia involves one or more of the building blocks of language, phonemes, morphology, lexis, syntax, and semantics; and the deficits occur in various clusters or patterns across the spectrum. The degree of impairment varies across modalities, with written language often, but not always, more affected than spoken language. In some cases, understanding of language is relatively preserved, in others both production and understanding are affected. In addition to varied degrees of impairment in spoken and written language, any or more than one component of language can be affected. At the most severe end of the spectrum, a person with aphasia may be unable to communicate by either speech or writing and may be able to understand virtually nothing or only very limited social greetings. At the least severe end of the spectrum, the aphasic speaker may experience occasional word finding difficulties, often difficulties involving nouns; but unlike difficulties in recalling proper nouns in normal aging, word retrieval problems in mild aphasia includes other word classes. Descriptions of different clusters of language deficits have led to the notion of syndromes. Despite great variations in the condition, patterns of language deficits associated with different areas of brain damage have been influential in understanding language-brain relationships. Increasing sophistication in language assessment and neurological investigations are contributing to a greater, yet still incomplete understanding of language-brain relationships.

Article

Anthony P. Kontos and Jamie McAllister-Deitrick

Concussions affect millions of athletes of all ages each year in a variety of sports. Athletes in certain sports such as American football, ice hockey, rugby, soccer, and combative sports like boxing are at higher risk for concussion. Direct or indirect mechanical forces acting on the skull and brain cause a concussion, which is a milder form of brain injury. Conventional neuroimaging (e.g., computerized tomography [CT], magnetic resonance imaging [MRI]) for concussion is typically negative. Concussions involve both neurometabolic and subtle structural damage to the brain that results in signs (e.g., loss of consciousness [LOC], amnesia, confusion), symptoms (e.g., headache, dizziness, nausea), and functional impairment (e.g., cognitive, balance, vestibular, oculomotor). Symptoms, impairment, and recovery time following concussion can last from a few days to weeks or months, based on a variety of risk factors, including younger age, female sex, history of concussion, and history of migraine. Following a concussion, athletes may experience one or more clinical profiles, including cognitive fatigue, vestibular, oculomotor, post-traumatic migraine (PTM), mood/anxiety, and/or cervical. The heterogeneous nature of concussion warrants a comprehensive approach to assessment, including a thorough clinical examination and interview; symptom inventories; and cognitive, balance, vestibular, oculomotor, and exertion-based evaluations. Targeted treatment and rehabilitation strategies including behavior management, vestibular, vision, and exertion therapies, and in some cases medication can be effective in treating the various concussion clinical profiles. Some athletes experience persistent post-concussion symptoms (PCS) and/or psychological issues (e.g., depression, anxiety) following concussion. Following appropriate treatment and rehabilitation strategies, determination of safe return to play is predicated on being symptom-free and back to normal levels of function at rest and following exertion. Certain populations, including youth athletes, may be at a higher risk for worse impairment and prolonged recovery following concussion. It has been suggested that some athletes experience long-term effects associated with concussion including chronic traumatic encephalopathy (CTE). However, additional empirical studies on the role of concussion on CTE are needed, as CTE may have multiple causes that are unrelated to sport participation and concussion.