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Environmental Experience and Plasticity of the Developing Brain von Sale, Alessandro (eBook)

  • Erscheinungsdatum: 04.02.2016
  • Verlag: Wiley-Blackwell
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Environmental Experience and Plasticity of the Developing Brain

Environmental Experience and Plasticity of the Developing Brain goes beyond the genetic basis of neurodevelopment. Chapters illuminate the external factors that can dramatically impact the brain early in life and, consequently, the eventual accomplishment of developmental milestones and the construction of adult behavior and personality. Authored and edited by leaders in this rapidly growing field, Environmental Experience and Plasticity of the Developing Brain not only surveys preexisting literature on the effects of environment versus genetics, but also discusses more recent studies on the impacts of neurodevelopment in terms of maternal stimulation, environmental enrichment and sensory deprivation. The book also includes key examples of environmental impacts on preexisting genetic syndromes leading to developmental disabilities. Focus is also given to the consequences of early adverse experience in primates, as well as neurobiological and behavioral consequences in institutionalized human children and the reversibility of such consequences. Environmental Experience and Plasticity of the Developing Brain encompasses a broad area of research in the field of developmental neurobiology and offers a unique combination of different examples of environmental factors affecting brain development and behavior.


    Format: ePUB
    Kopierschutz: AdobeDRM
    Seitenzahl: 240
    Erscheinungsdatum: 04.02.2016
    Sprache: Englisch
    ISBN: 9781118931660
    Verlag: Wiley-Blackwell
    Größe: 4258 kBytes
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Environmental Experience and Plasticity of the Developing Brain

Chapter 1
Environmental enrichment and brain development

Alessandro Sale1, Nicoletta Berardi2 and Lamberto Maffei1

1 Neuroscience Institute, National Research Council (CNR), Pisa, Italy

2 Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, Florence, Italy
Introduction: critical periods and experience-dependent plasticity in brain circuits

The term "plasticity" refers to the ability of the nervous system to reorganize its connections functionally and structurally in response to changes in environmental experience. This property underlies the adaptive development and remodeling of neuronal circuitry that makes brain development, behavioral flexibility, and long-term memory possible.

Plasticity is particularly high during developmental time windows called critical periods (CPs), when experience is crucial in promoting and regulating neural maturation and, consequently, the behavioral traits of the newborn, in every vertebrate species tested so far, from birds to rodents to primates (Berardi et al., 2000). Essentially, a CP is a phase of exceptionally high sensitivity to experience displayed by developing neural circuits. During CPs, experience exerts a key role in building the precise assembly of connections that endows each individual with his/her unique characteristics. Different species show different CPs for the same function, in good accordance with a different time course of development and life span. On the other hand, distinct functions show different CPs in the same species, correlating with different time courses of development in different brain areas.

Essential information on developmental brain plasticity and CPs has been provided by studies focusing on the primary visual cortex (V1), which has been for decades the election model for studying experience-dependent plasticity in the brain. The pioneering experiments performed by Hubel and Wiesel showed how dramatically can early sensory deprivation affect the anatomy and physiology of the visual cortex ( Figure 1.1 ). Many neurons in the visual cortex are binocular, that is, receive input from both eyes, and exhibit different degrees of dominance from either eye, a property called ocular dominance. Hubel and Wiesel reported that, early in development, reducing the visual input to one eye by means of lid suture, a treatment classically referred to as monocular deprivation (MD), disrupts ocular dominance of V1 cells, with a loss of neurons driven by the deprived eye and a strong increment in the number of cells driven by the open eye, and reduces the number of binocular neurons (Wiesel and Hubel, 1963). The imbalance of activity between the two eyes results in remarkable anatomical changes in V1, with a shrinkage of the deprived eye ocular dominance columns, those layer IV regions that receive thalamic inputs driven by the closed eye, and in the expansion of the open eye's columns (Hubel et al., 1977; Shatz and Stryker, 1978; LeVay et al., 1980; Antonini and Stryker, 1993), accompanied by a remodeling of cortical horizontal connections (Trachtenberg and Stryker, 2001). At the behavioral level, if the condition of MD is protracted for a long period during development, it eventually leads to lower than normal visual acuity and contrast sensitivity values for the deprived eye (amblyopia), together with a deterioration of binocular vision. Strikingly, the same manipulation of visual experience appeared to be ineffective in the adult (LeVay et al., 1980), leading to the characterization of the first and most widely studied example of CP (Berardi et al., 2000; Berardi et al., 2003; Knudsen, 2004; Hensch, 2005a, 2005b; Levelt and Hubener, 2012).

Figure 1.1 Critical period (CP) for ocular dominance plasticity in the rat visual cortex. (a) Schematic representation of the time c

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