YOUR BRAIN
To discover the inner regions of the brain, we need to slice the two
hemispheres apart, which requires cutting through a massive bundle of
connecting nerve fibres known as the corpus callosum – described by the
fictional doctor Dr Gregory House as the “George Washington Bridge”
of the brain. This great connector has around two hundred million
neurons passing through it and is responsible for most of the cross-talk
between the two hemispheres.
A curious feature of the corpus callosum is how much it varies in size
between one person and another, with some people having up to three
times as many connecting fibres as others. It used to be thought that this
variation was associated with gender and handedness but hundreds of
studies have failed to turn up any consistent evidence for this. Another
important factor could be “hemispheric dominance” – that is, whether it
is the left or right side of your brain that is the more dominant.
Two Hawaii-based researchers, Bruce Morton and Stein Rafto, tested
this idea in a paper published in 2006. They first established the hemi-
T The brain is grey. People will often talk about grey matter or
their grey cells. There is more than a grain of truth in this. Much
of the brain is indeed grey in colour. In reality, however, a lot of
it is also white, thanks to the fatty insulation that covers many of
our brain cells, and much of it is also red or pink because of all the
circulating blood. So if you saw a real, living brain in all its glory
it would probably appear greyish pink. Preserved brains have a
more pronounced dull grey appearance because of the fixatives
used to stop them from decaying.
T Adult brains can’t grow new cells. A myth that used to be
supported by the best scientific evidence. Neuroscientists believed
that we are born with all the brain cells we’ll ever have. Research
conducted over the last couple of decades, however, has shown
that this simply isn’t the case. Adult brains can and do grow new
brain cells, a process that’s known as “adult neurogenesis”. The
most fertile brain region when it comes to new cells is the hippoc-
ampus, a structure involved in memory. In fact, thousands of new
brain cells are created in the hippocampus every day. Intriguing
new research suggests that stress inhibits the creation of new
brain cells, while learning, exercise and anti-depressants all seem
to boost cell birth.