Can Neuroscience Change Our Minds? by Hilary Rose Steven Rose

Author:Hilary Rose,Steven Rose
Language: eng
Format: epub
Publisher: John Wiley & Sons, Inc.
Published: 2016-08-01T04:00:00+00:00

(1) Synapses – the more the better?

According to one of the early interventionist training programmes drawing strongly on Perry, ‘an adverse environment will lead to a child having 25% less synapses or connections in their brains than they could have had, while a stimulating environment can lead to 25% more connections’.18 One of the key features of the early development of the brain is a vast over-production of neurons and synapses. Just as it takes myriads of sperm to ensure that one is able to reach and fertilize the egg, so it takes myriads of neurons to be born during development to ensure that some survive and wire up appropriately. A process called apoptosis – programmed cell death – then removes the surplus. So too with synapses, whose proliferating numbers during early development are steadily pruned away, so that by adulthood in some brain regions there are less than half of those present at age three. (These anatomical measurements can only be made post-mortem; there is no way of counting cells or synapses in the living human brain.) Neuroscientists believe that this pruning of redundant synapses both removes unused connections and improves the efficiency of those that remain. Another problem with the synapse number claim is that it implies that once a synapse is made, it remains in place. However, time-lapse studies of the brain in experimental animals shows that synapses are highly dynamic, continually being modified, disappearing and being reformed throughout life. (‘Use it or lose it’ is no bad slogan.) Indeed, this remodelling capacity – plasticity – is the neural mechanism that enables a person to learn from experience, remember and change how they respond. Every thought or action leaves its trace in the brain. So the claim about the significance of synapse numbers is misleading.

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