This is my summary of chapter two of The Shallows: How the internet is changing the way we read, think and remember, by Nicholas Carr. (For my summary of chapter 1, please click here!)
Friedrich Nietzsche suffered from severe health problems through most of his life, so severe that he had to resign his university post as a professor of philology at the University of Basel when he was just 34 years old in 1879.
By 1881, he found that his vision was failing and that if tried to focus on reading or writing, he would soon be defeated by crushing headaches and even vomiting.
In desperation, he ordered a Malling-Hansen Writing Ball, basically a typewriter, but funky in the extreme, and in fact the fastest one made to date: with practice one could type up to 800 characters a minute.
This typewriter saved Nietzsche, at least for a time, as once he’d learned to use it, he was able to transfer words from his mind to the page with his eyes shut, thus avoiding the crippling headaches that came with regular writing.
But the device had a subtler effect on his work: one of his closest friends, Heinrich Koselitz, noticed a change in the style of his writing. There was a new forcefulness to it, as though the iron in the machine was being transferred onto the page.
Nietzsche agreed, stating in a letter to his friend that ‘out writing equipment takes part in the forming of our thoughts’.
Recent studies have found that neurons are both like and unlike other cells in our bodies. Neurons have central cores, or somas, which carry out the functions of common to all cells, but they also have two kinds of tentacle like appendages – axons and dendrites – that transmit and receive electric pulses.
When a neuron is active, a pulse flows from the soma to the tip of the axon, where it triggers the release of chemicals called neurotransmitters which flow across synapses and attach themselves to a dendrite of a neighbouring neuron, triggering (or suppressing) a new electric pulse in that cell.
There are 100 billion neurons in the human brain, which take many different shapes and range in length from a few tenths of a millimeter to a few feet. A single neuron has one axon, and many dendrites and dendrites and axons can each have multiple branches and synaptic terminals.
The average neuron makes about 1000 synaptic connections.
In other words, our brain is incredibly complex, consisting of millions of billions of connections.
Thoughts, memories, emotions, and basically our entire sense of who we are all emerge from the electrochemical interactions of neurons mediated by synapses.
The historically mistaken idea of the ‘mechanical brain’
Throughout the 20th century, most biologists and neurologists continued to believe, as many still do, that the structure of adult brain never changed: the brain was viewed as something which was malleable in childhood but became fixed in adulthood. The only structural change the brain would go through was that of decay.
There were a few heretics such as British biologist J.Z. Young and psychologist William James, but the mainstream scientific view was of the fixed structure adult brain.
Descartes was one of the first people to popularise this idea. For Descartes, in his Meditations of 1641 he claimed the brain consisted of two separate spheres: the material and the ethereal. Descartes saw the physical brain as purely mechanical instrument like a clock or a pump, while the conscious mind was more ethereal…
As reason became more part of the enlightenment, the idea of the ethereal disappeared and the idea of the brain as something which was hardwired took root.
This conception fitted in well with the industrial age obsession with mechanical contraptions. The brain was conceived of a machine that worked in a set way.
From the hardwired brain to neuroplasticity
In 1968, Michael Merzenich mapped out the neural circuitry of monkey brains, using micro-electrodes.
He cut open a monkey’s skull, inserted a micro-electrode into a particular part of the brain he new to be associated with hands. He then prodded various parts of the monkey’s hand until the electrode lit up. He repeated this process thousands of times, inserting the electrode into slightly different parts of the brain, with five monkeys. Eventually he had the most detailed neural map (to date) of which specific parts of the brain registered sensation from which part of the hand.
In the second phase of the experiment, Merzenich moves on to severing some of the peripheral nerves in the monkeys’ hands, which grow back haphazardly.
He then proceeded with the prodding and electrodes in the brain to see how the brain reacts. At first the brain is confused: when the tip of the left finger is prodded (for example), the brain thinks the sensation is actually coming from somewhere else, maybe the middle finger.
However, after a few months the brain has remapped itself, and the new map corresponds to the new nerve structure which has grown back in the hands: prod a little finger, and the part of the brain associated with the little finger lit up again.
What Merzenich had discovered was evidence of neuroplasticity in mature primates.
He published his findings in April 1972 in the Journal ‘Brain Research’, but his findings were ignored, it seems, because they lay outside the dominant paradigm of the time which held that the adult brain was immutable and resistant to change.
He persisted in his research, and uncovered further evidence of neuroplasticity, but his findings were ignored for at least a decade more. In 1983 he wrote in another journal…
‘…. these results were completely contrary to a view of sensory systems as consisting of a series of hardwired machines.’
Eventually, however, Merzenich’s research gained credibility with the establishment, and a re-reading of the research-record finds a tradition of ‘deviants’, going back to Freud, that have either theorised or found evidence of the active-learning, ‘neuroplastic’ brain.
More recent evidence for neuroplasticity
From the 1980s research on neuroplasticity evolved with ever more microscopic brain probing equipment, and extensive research has now been carried out on both animals and humans. The evidence today suggests a very high degree of brain plasticity in several neuro circuits – not just those associated with physical sensation, but also seeing hearing, feeling and memory.
Our brains, it appears, are massively plastic. They may get less plastic as we age, but the ability of our brains to reform themselves and create new new neural pathways in response to new experiences carries on into our old age. Our neurons are always breaking old connections and forming new ones, and brand-new nerve cells are always being created.
Every time we perform a task or experience a sensation, whether physical or mental, a set of neurons in our brains is activated… as the same experience is repeated, the synaptic links between the neurons grow stronger and more plentiful. What we learn is embedded in the ever-changing cellular connections inside our head, forming true vital paths. This has become known as Hebbs rule – cells that fire together wire together.
One experiment which demonstrate how synaptic connections can change in relation to experience is Eric Kandel’s Sea Slug (Aplysia) experiment. This found that if you touch a sea slugs gill, it will normally immediately and reflexively recoil. However, if you repeatedly touch the gill without oing it harm, ,the recoil reaction stops.
Neuroplasticity: common ground for nature and nurture views of human development
The plasticity of our synapses brings into harmony two philosophies of the individual that have for centuries been in conflict: the nurture versus nature view of the mind.
This conflict of views stretches all the way back to very beginning of Enlightenment thought. John Locke’s Tabula Rasa empiricist view of the individual as a blank state is one of the earliest expressions of the nurture view of human development, while Kant’s rationalist view of the individual as consisting of a mental template at birth which determines what we can know is one of the earliest theories of human development which favours the role of nature over nurture.
The opposing philosophies of the empiricist and the rationalist find common ground in the synapse – our genes specify many of the connections between neurons, but our experiences regulate the strength or the long-term effectiveness of these connections.
The brain is not the machine we once thought it to be…… the cellular components do not form permanent structures or play rigid roles. There are various examples and experiments which demonstrate this:
- If a person is struck blind, the visual cortex will be redeployed and used for audio processing to mitigate the loss of site.
- Those struck deaf will develop stronger peripheral vision.
- Edward Taub’s success with ‘intensive therapies’ for stroke victims whose brains have been damaged so that they have lost control over one side of their body. His therapies basically involve stroke victims repeating repetitive tasks with their ‘stricken’ limbs until, eventually their brains are reprogrammed, and movement restored.
NB Brain plasticity is not just limited to extreme cases. It seems that the map of the brain is changed in subtle ways even when we simply learn a new skill. The brain is so plastic, in fact, that it can reprogram itself on the fly, change the way it functions.
Two experiments which suggest that lived experience changes the shape of the brain….
- The posterior hippocampus region (the bit that deals with spatial awareness) of the brain of London cab drivers is larger than a normal brain. The longer serving cab drivers had the largest posterior hippos.
- An experiment with non-piano players got two groups of people to learn a short simple piece. One group practiced the piece 2 hours a day for 5 days, the second group just imagined practising the piece. Both improved, and both demonstrated the same brain changes.
According to Alvaro Pascual-Leone, ‘Plasticity is the normal ongoing state of the nervous system throughout the lifespan’. It may just be that the genius of our brains lies not in it’s complex structure, but in the lack of a structure.
In other words, we become neurologically what we think!
The downsides of neuroplasticity
Unfortunately, plastic does not mean elastic.
The paradox of plasticity is that for all our mental flexibility, it can also lock us into rigid behaviours. Once we have activated new circuitry in our brain, we long to keep it activated. In addition to being the mechanism for development and learning, plasticity can be a cause of pathology’.
Neuroplasticity has been linked to afflictions such as depression, OCD and tinnitus, and it works in much the same way as addictive drugs… the more we focus on these negative traits, the more we get locked into them.
A final problem is that there appears to be a rule of ‘survival of the busiest’. There is an opportunity cost associated with reinforcing any set of neural pathways. If we reinforce one set, others become less prominent. In other words, we cannot be skilled at everything!
In conclusion (to chapter 2)
It is comforting to think of our brain as existing in ‘splendid isolation’ but the research evidence suggests that this is not the case – our brains are a product of our experience. They change as we experience new things.
For my summary of chapter three, please click here. To purchase the whole book, please click the link below…
Image Sources
The Enlightenment mind as machine image
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