Review ArticleCare for Child Development: Basic Science Rationale and Effects of Interventions
Introduction
In 2007, over 200 million children under age 5 years were estimated not to be fulfilling their developmental potential [1]. Child development is largely dependent on the quality of early experiences. Early intervention can enhance the brain’s potential through cerebral plasticity. The hypothesis underlying intervention programs claims that early intervention does not merely help the brain to achieve a predetermined potential, but that it enhances the underlying brain’s potential altogether. A convincing body of evidence from neurobiology supports this hypothesis. The challenge will be to identify those interventions that are effective, safe, and practical, based not only on field experience but also on basic science data. Although similar in action, interventions that enhance developmental potential are distinct from factors that provide neuroprotection during or after a specific insult. Fig 1 depicts the potential relationship between neuroprotection and neural recovery and enhancement. We will present basic science evidence for both kinds of interventions. The implementation of early interventions will require the support and commitment of developmental psychologists, primary care providers, parents, policymakers, and local and global communities. Basic scientists can also contribute to this process. Through a cooperative effort, we should be able to increase the effectiveness of programs aimed at enhancing childhood development and the awareness of the benefits of early intervention.
Section snippets
Cerebral Plasticity and Its Role in Cerebral Development and Recovery
Cerebral plasticity refers to the brain’s ability to learn, remember, forget, reorganize, and recover from injury. The conceptual framework for plasticity was formulated in 1949 by Hebb, who postulated that when one cell excites another repeatedly, a change occurs in one or both cells that contributes to their stability [2]. In other words, “neurons that fire together, wire together.” Neurogenesis and synaptogenesis comprise the activity-dependent mechanisms underlying cerebral plasticity.
Evidence Demonstrating Enhancement of Cerebral Development and Stages of Plasticity in Cerebral Development
The processes of neurulation and neuronal proliferation, migration, and differentiation begin at conception. At birth, most neurons have migrated to their final locations within the brain. Subcortical structures can be clearly delineated, and resemble their adult forms (Figure 2, Figure 3). Organization of the human cortex begins during gestation and continues postnatally and into early adulthood (Fig 4). Cortical organization is characterized by dendritic and axonal growth, the production of
Erythropoeitin
The heightened plasticity of the developing brain increases its susceptibility to injury, and also permits its recovery from injury. Interventions that modulate the molecules and processes involved in neurogenesis and synaptogenesis improve the brain’s ability to recover. For example, the neuroprotective actions of erythropoietin are well established in animal models of ischemic brain injury. The immature nervous system is especially sensitive to the effects of hypoxia and hypoxia-induced
Magnetic Resonance Imaging-Based Studies
Functional magnetic resonance imaging techniques have contributed to our understanding of cerebral plasticity and the brain’s response to injury. Functional magnetic resonance imaging studies of children who manifested left hemispheric strokes at an early age demonstrated that language function is capable of reorganizing in the right hemisphere [64] (Fig 5). Similarly, a functional magnetic resonance imaging study of patients with complex partial epilepsy and left hemispheric foci revealed
Conclusions and Outlook for the Future
Evidence from neurobiology indicates that early intervention is capable of changing the structure and function of the brain. The biologic mechanisms of neurogenesis, synaptogenesis, and rewiring underlie cerebral plasticity and the brain’s ability to adapt and recover from injury. Environmental enrichment alone was demonstrated to increase neurogenesis and synaptogenesis in the brain. Erythropoietin, growth factors, antidepressants, and stem cells comprise some of the biologic agents capable of
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