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Why babies need experiences

Watch this video. Professor Jane Barlow introduces the concepts of experience-expectant and experience-dependent brain development.
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You will by now have watched the three Russian video clips and read the research describing the impact of early pervasive neglect. I hope that you will also have contributed to the discussion. One of the reasons for the significant impact of the environment on Faya and other such babies is that the post-natal period is a key time for brain development. At full term, a baby’s brain has 100 billion neurons, but the brain is not fully developed. This is evolution’s answer to making birth safer for both mother and baby by reducing the size of the baby’s cranium.
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The baby’s brain, therefore, has to be wired up after birth, and as a result will increase in weight from around 400 grammes at birth to 1,000 grammes at one year of age. This increase in weight is caused by the bulk of the synapses, the connections between the neurons, that are being developed. Synaptogenesis is the process by which connections are made between neurons in the nervous system to form neural pathways. Although this takes place across the lifespan as a result of the plasticity of the human brain, there is an explosion of synapse formation that occurs during early brain development known as exuberant synaptogenesis.
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The first few years of life are important, because the brain is very sensitive during this period to early input and because there is also synoptic pruning in which pathways that are not used may be lost. The wiring of the baby’s brain during this period takes place as a result of both nature, such as genes, and nurture, such as the environment in which a baby grows up. In terms of the nurture or environmental component, a baby’s brain develops as a consequence of both experience-expectant and experience-dependent processes. Aspects of the brain that are defined as being experience-expectant include vision and hearing, social and emotional development, language, and higher cognitive functions.
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The average or normal environment provides infants with the necessary input to develop the neural connections to enable the baby to function across these domains. However, if the baby’s brain does not receive input during these critical periods, these functions will be lost permanently. For example, if one of the baby’s eyes is covered during the first year of life, the baby will eventually be blind in that eye. Similarly, if he’s not exposed to language during the early years, language development will fail to develop normally. And in terms of socio-emotional development, if the infant doesn’t learn how to form an attachment during the first few years of life, their later ability for any attachment will be severely impeded.
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We saw this demonstrated with Faya in the Russian orphanages video. Many aspects of the baby’s developing brain are, however, what is known as experience-dependent. And these include their socio-emotional development, language, and some of the higher aspects of cognitive development. They’re described as experience-dependent because the neural connections that are established depend entirely on the quality of the environmental input. For example, while all babies are born with a capacity for language development, the language that they speak will depend on the languages to which they are exposed.
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Similarly, if a baby is limited to interactions with a primary caregiver who has a restricted number of words, the baby’s language development will also be restricted and less optimal than the baby whose primary caregiver uses a more elaborated language. Socio-emotional development is another area that is influenced by experience-dependent processes, and in particular the nature of the environmental input during these key sensitive periods. The term ‘sensitive period’ means that although this is the optimal time for development of aspects of the child’s functioning such as language, socio-emotional development, the brain is highly plastic and later input could compensate for early deficits.
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In this course, we’re primarily going to be focusing on experience-dependent brain development, because we’re primarily interested in the way in which the quality of the different parenting environments to which babies are exposed shape their developing mind and sense of who they are as a person. Watch the next video clip about the way in which experiences build brain architecture before going on to the next section, which examines in more detail exactly what the baby needs in terms of early environmental input to optimise their early brain development.
In this video we examine the development of the brain during the first two postnatal years in terms of the rapid neural development (i.e. synaptogenesis) that is taking place during this period as a result of the fact that the brain is highly sensitive to environmental input at this time.
We distinguish in particular between ‘experience-expectant’ and ‘experience-dependent’ types of brain development. The former affects a range of aspects of brain development including vision and hearing, social and emotional development, language and higher cognitive functions. Experience-expectant refers to the fact that the average or normal environment provides infants with the necessary input to develop the neural connections to enable the baby to function across these domains. However, if the baby’s brain does not receive input during these critical periods, these functions will be lost permanently.
Many aspects of the baby’s developing brain are what is also known as experience-dependent and these include their socioemotional development, language and some of the higher aspects of cognitive development. They are described as experience-dependent because the neural connections that are established depend entirely on the quality of the environmental input. For example, while all babies are born with a capacity for language development, their ability to communicate verbally will depend on their exposure to language during their early years.
While most babies do not experience the type of severe deprivation in infancy characterised by Russian or Romanian orphanages, all children experience diverse environments that will affect their experience-dependent brain development. In this course we are going to be examining one particular aspect of that diversity…their parent’s mind.
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Babies in Mind: Why the Parent's Mind Matters

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