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"Understanding the Brain: The Birth of a Learning Science", 2007, page 42
Plasticity and Sensitive Periods
Neuroscientists have known for some time that the brain changes significantly over the lifespan as a response to learning experiences. This flexibility of the brain to respond to environmental demands is called plasticity.
The brain is physically modified through strengthening, weakening, and elimination of existing connections, and the growth of new ones. The degree of modification depends on the type of learning that takes place, with long-term learning leading to more profound modification.
The brain’s ability to remain flexible, alert, responsive and solution-oriented is due to its lifelong capacity for plasticity. Before, it was thought that only infant brains were plastic. This was due to the extraordinary growth of new synapses paralleled with new skill acquisition.
However, data uncovered over the last two decades have confirmed that the brain retains its plasticity over the lifespan. And because plasticity underlies learning, we can learn at any stage of life albeit in somewhat different ways in the different stages (Koizumi, 2003; OECD, 2002).
Plasticity can be classified into two types: experience-expectant and experience-dependent.
The plasticity experience-expectant describes the genetically-inclined structural modification of the brain in early life.
The plasticity experience-dependent the structural modification of the brain as a result of exposure to complex environments over the lifespan.
Many researchers believe that experience-expectant plasticity characterises species-wide development: it is the natural condition of a healthy brain, a feature which allows us to learn continuously until old age.
In parallel to plasticity, learning can also be described as experience-expectant or experience-dependent.
Experience-expectant learning takes place when the brain encounters the relevant experience, ideally at an optimal stage termed a “sensitive period”. Sensitive periods are the times in which a particular biological event is likely to occur best.
Scientists have documented sensitive periods for certain types of sensory stimuli such as vision and speech sounds, and for certain emotional and cognitive experiences, such as language exposure.
However, there are many mental skills, such as vocabulary acquisition and the ability to see colour, which do not appear to pass through tight sensitive periods. These can be considered as experience-dependent learning that takes place over the lifespan.
The different types of plasticity play a different role in different stages of life. The following section takes the three different stages of life, namely early childhood, adolescence, and adulthood (including ageing adults), and describes the distinctive characteristics of the learning process in each stage.
The brain is physically modified through strengthening, weakening, and elimination of existing connections, and the growth of new ones. The degree of modification depends on the type of learning that takes place, with long-term learning leading to more profound modification.
The brain’s ability to remain flexible, alert, responsive and solution-oriented is due to its lifelong capacity for plasticity. Before, it was thought that only infant brains were plastic. This was due to the extraordinary growth of new synapses paralleled with new skill acquisition.
However, data uncovered over the last two decades have confirmed that the brain retains its plasticity over the lifespan. And because plasticity underlies learning, we can learn at any stage of life albeit in somewhat different ways in the different stages (Koizumi, 2003; OECD, 2002).
Plasticity can be classified into two types: experience-expectant and experience-dependent.
The plasticity experience-expectant describes the genetically-inclined structural modification of the brain in early life.
The plasticity experience-dependent the structural modification of the brain as a result of exposure to complex environments over the lifespan.
Many researchers believe that experience-expectant plasticity characterises species-wide development: it is the natural condition of a healthy brain, a feature which allows us to learn continuously until old age.
In parallel to plasticity, learning can also be described as experience-expectant or experience-dependent.
Experience-expectant learning takes place when the brain encounters the relevant experience, ideally at an optimal stage termed a “sensitive period”. Sensitive periods are the times in which a particular biological event is likely to occur best.
Scientists have documented sensitive periods for certain types of sensory stimuli such as vision and speech sounds, and for certain emotional and cognitive experiences, such as language exposure.
However, there are many mental skills, such as vocabulary acquisition and the ability to see colour, which do not appear to pass through tight sensitive periods. These can be considered as experience-dependent learning that takes place over the lifespan.
The different types of plasticity play a different role in different stages of life. The following section takes the three different stages of life, namely early childhood, adolescence, and adulthood (including ageing adults), and describes the distinctive characteristics of the learning process in each stage.
"Understanding the Brain: The Birth of a Learning Science", 2007, page 42
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