Questions 14–26
, which are based on Reading
Passage 2 below.
The Triune
1
Brain
The first of our three brains to evolve is what scientists call the reptilian
cortex. This brain sustains the elementary activities of animal survival such as
respiration, adequate rest and a beating heart. We are not required to consciously
“think” about these activities. The reptilian cortex also houses the “startle centre”, a
mechanism that facilitates swift reactions to unexpected occurrences in our
surroundings. That panicked lurch you experience when a door slams shut somewhere
in the house, or the heightened awareness you feel when a twig cracks in a nearby
bush while out on an evening stroll are both examples of the reptilian cortex at work.
When it comes to our interaction with others, the reptilian brain offers up only the
most basic impulses: aggression, mating, and territorial defence. There is no great
difference, in this sense, between a crocodile defending its spot along the river and a
turf war between two urban gangs.
Although the lizard may stake a claim to its habitat, it exerts total indifference
toward the well-being of its young. Listen to the anguished squeal of a dolphin
separated from its pod or witness the sight of elephants mourning their dead, however,
and it is clear that a new development is at play. Scientists have identified this as the
limbic cortex. Unique to mammals, the limbic cortex impels creatures to nurture their
offspring by delivering feelings of tenderness and warmth to the parent when children
are nearby. These same sensations also cause mammals to develop various types of
social relations and kinship networks. When we are with others of “our kind” – be it
at soccer practice, church, school or a nightclub – we experience positive sensations
of togetherness, solidarity and comfort. If we spend too long away from these
networks, then loneliness sets in and encourages us to seek companionship.
Only human capabilities extend far beyond the scope of these two cortexes.
Humans eat, sleep and play, but we also speak, plot, rationalise and debate finer
points of morality. Our unique abilities are the result of an expansive third brain – the
1
Triune = three-in-one
© The British Council 2012. All rights reserved.
7
neocortex – which engages with logic, reason and ideas. The power of the neocortex
comes from its ability to think beyond the present, concrete moment. While other
mammals are mainly restricted to impulsive actions (although some, such as apes, can
learn and remember simple lessons), humans can think about the “big picture”. We
can string together simple lessons (for example, an apple drops downwards from a
tree; hurting others causes unhappiness) to develop complex theories of physical or
social phenomena (such as the laws of gravity and a concern for human rights).
The neocortex is also responsible for the process by which we decide on and
commit to particular courses of action. Strung together over time, these choices can
accumulate into feats of progress unknown to other animals. Anticipating a better
grade on the following morning’s exam, a student can ignore the limbic urge to
socialise and go to sleep early instead. Over three years, this ongoing sacrifice
translates into a first class degree and a scholarship to graduate school; over a
lifetime, it can mean ground-breaking contributions to human knowledge and
development. The ability to sacrifice our drive for immediate satisfaction in order to
benefit later is a product of the neocortex.
Understanding the triune brain can help us appreciate the different natures of
brain damage and psychological disorders. The most devastating form of brain
damage, for example, is a condition in which someone is understood to be brain
dead.
In this state a person appears merely unconscious – sleeping, perhaps – but this is
illusory. Here, the reptilian brain is functioning on autopilot despite the permanent
loss of other cortexes.
Disturbances to the limbic cortex are registered in a different manner. Pups
with limbic damage can move around and feed themselves well enough but do not
register the presence of their littermates. Scientists have observed how, after a limbic
lobotomy
2
, “one impaired monkey stepped on his outraged peers as if treading on a
log or a rock”. In our own species, limbic damage is closely related to sociopathic
behaviour. Sociopaths in possession of fully-functioning neocortexes are often shrewd
and emotionally intelligent people but lack any ability to relate to, empathise with or
express concern for others.
One of the neurological wonders of history occurred when a railway worker
named Phineas Gage survived an incident during which a metal rod skewered his
skull, taking a considerable amount of his neocortex
with it. Though Gage continued
to live and work as before, his fellow employees observed a shift in the equilibrium of
his personality. Gage’s animal
propensities were now sharply pronounced while his
intellectual abilities suffered; garrulous or obscene jokes replaced his once quick wit.
New findings suggest, however, that Gage managed to soften these abrupt changes
over time and rediscover an appropriate social manner. This would indicate that
2
Lobotomy = surgical cutting of brain nerves
© The British Council 2012. All rights reserved.
8
reparative
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