Sunday 12 December 2010

When Certain Matters Must be Learnt?

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Are There Critical Periods to Learning? (1)

When Certain Matters Must be Taught and Learnt?


The influence of the intense synaptogenesis early in life on the adult brain is not yet known, but it is known that adults are less capable of learning certain things. Anyone who starts to learn a foreign language later in life, for example, will in all likelihood always have a “foreign accent”; the virtuosity of a late learner of an instrument will in all probability never equal that of a child practised with the same musical instruction from the age of 5.

Does this mean that there are periods of life when certain tasks can no longer be learned? Or are tasks merely learned more slowly or differently at different times?

For a long time it was believed that the brain loses neurons with age, but the measures opened by new technologies have challenged this certainty. Terry and his colleagues showed that the total number of neurons in each area of the cerebral cortex is not age-dependent but only the number of “large” neurons. Nerve cells shrink, resulting in a growing number of small neurons but the aggregate number of all neurons remains the same.

Certain parts of the brain, like the hippocampus, have recently been found actually to generate new neurons throughout the lifespan. The hippocampus is, among other things, involved in spatial memory and navigation processes (Burgess and O’Keefe, 1996).

Research comparing London taxi drivers with random other citizens suggests a strong relationship between the relative size and activation of the hippocampus, on the one hand, and a good capacity for navigation, on the other; there is a positive correlation between the enlargement of the auditory cortex and the development of musical talent, as there is growth of motor areas of the brain following intense training of finger movements. In the latter case, changes in the neuron network configuration linked to the learning could be measured using brain imaging from the fifth day of training, i.e. after an extremely brief period of learning.

The processes that remodel the brain – neuron synaptogenesis, pruning, development, and modification – are grouped together under the same term: “Brain Plasticity”. Numerous studies have shown that the brain remained plastic throughout the lifespan, in terms of numbers of both neurons and synapses.

"Understanding the Brain", The Birth of a Learning Science, 2007, page 112