Brain plasticity--What is it and how extraordinary can it be?

Brain plasticity (also known as cortical plasticity orand temporal lobe. Professional musicians who
neuroplasticity) is the ability of the brain to reorganizepractice at least 1hour per day) have a highest
itself – forming new brain cells and newvolume of neural tissue in these areas. Amateur
information processing connections between thosemusicians in turn have more brain mass in those areas
cells, and new functions for those cells.than non-musicians.
Neuroplasticity is known to occur in the brain in theBrain plasticity as a result of skill acquisition and
following situations:extensive learning in specialist areas is the norm.
- During infancy and childhood, and into youngCortical territory shifts over time in response to the
adulthood: when the immature brain organizes itself.knowledge and skills we acquire.
- Through adulthood: whenever we form a newShort term changes: studying for exams
memory, learn something new, or develop a new skill.In one brain imaging study, the brains of German
- In response to brain injury, disease or congenitalmedical students were scanned 3 months before
brain disorders such as blindness: to compensate fortheir medical exam and right after the exam. Their
lost functions or maximize remaining functions.brains were compared them to brains of students
Recent evidence demonstrates that the brain iswho were not studying for an exam. The medical
capable of remarkable widespread change andstudents’ brains showed showed changes in
adaptation throughout the lifespan – much moreregions of the parietal lobe as hippocampus –
than had previously been thought.areas of the brain known to have memory and
One remarkable type of brain plasticity occurs whenlearning functions.
parts of the brain that usually serve one cognitiveTraining intelligence and changing brain connections 
function are taken over by other parts of the brainRecently a brain training exercise has been
to serve other, completely different, functions.successfully developed that has been demonstrated
A general principle of brain function is what is calledto improve what is called fluid intelligence – our
localization: different perceptual and cognitiveability to reason and problem solve in new situations
functions are performed by different parts of the– as measured by standard IQ tests (link).
brain. Damage to one part of the brain can result in aTraining with this software has also been shown to
highly specific and selective deficit, while leavingincrease neural activity in part of the frontal lobe
remaining cognitive functions intact.known to be involved in higher cognitive functioning,
Blindness from birth and ‘cross modaland to increase the density of neurons’
plasticity’receptors for dopamine, a neurotransmitter involved
Blind individuals have to make some majorin higher cognition. This is called synaptic plasticity
adjustments in order to cope with and flourish in a– it occurs at the level of the connections
world that is designed for the sighted. Blind individualsbetween individual neurons.
develop heightened abilities in the use of theirThe most extraordinary example of brain plasticity of
remaining senses in order to compensate for theirthem all: hydrocephaly
loss of sight: their superior skills in tasks involvingThe brain is suspended in a fluid called cerebrospinal
touch and hearing has been established as a fact influid which baths the whole of the central nervous
laboratory settings.system. Without cerebrospinal fluid the brain would
In normal brains the back (anterior) region of the twocollapse under its own weight. Hydrocephalus –
hemispheres of the brain is specialized for processingmore commonly known as 'water on the brain' –
visual information. This part of the brain in eachis a condition in which there is an abnormal build up of
hemisphere is called the occipital lobe. Damage tocerebrospinal fluid. Without treatment, it can lead to
occipital lobes – perhaps in a car accident, orbrain damage and death. Pockets of cerebrospinal
through a stroke – results in blindness, but willfluid in the brain called ventricles can expand and in
leave all other sensory modalities and higher levelextreme cases the entire brain can be pushed by the
functions such as language and personality thoughtfluid into a small layer close to the skull.
unaffected.The British neurologist John Lorber has documented
over 600 scans of people with hydrocephalus and
What do the blind use the occipital lobes for if theyhas categorized them into four groups:
can’t see? Magnetic Resonance Imaging (fMRI)- those with nearly normal brains
and other brain imaging techniques have enabled us- those with 50-70% of the skull filled with
to answer this question. As normally sightedcerebrospinal fluid
individuals we use our vision – and our occipital- those with 70-90% of the cranium filled with
lobes - to read. Blind individuals, by contrast, use thecerebrospinal fluid
sense of touch to read braille. Recording the brain- those with 95% of the cranial cavity filled with
activity in individuals blind from birth when they readcerebrospinal fluid – the most severe group
braille shows that their occipital lobes light up – itOf the last group, which made up 10% of the study,
has been recruited to read brain by touch. Since onehalf were profoundly retarded.  The remaining half
modality (touch) is substituting for another modality– and this is the extraordinary testament to brain
(vision), this kind of plasticity is called ‘crossplasticity – had IQs greater than 100 (the
modal’.average IQ level). One young man in this category of
Additional experiments have also shown that blind‘virtually no brain whatsoever’ had an IQ of
individuals’ occipital lobes are used for speech126 and got a first class honours degree in
processing, a function usually performed in themathematics! Brains are normally around 1.5kgs. But
temporal and frontal lobes.these cases prove that 50-100 gram brains may
These discoveries are perhaps not that surprising,perform at a normal and even superior level.
given how ‘plastic’ the brain can be duringBelow is an MRI scan of a French civil servant’s
childhood. A similar kind of brain reorganisation can bebrain! The image shows that this 44-year-old
seen by comparing bilingual vs monolingual speakers:man’s brain is little more than an outer shell in
an area in the left  parietal lobe is significantly largercomparison to a normal brain. The region labled LV is
in bilingual brains than monolingual brains.just fluid in this brain - normally it is packed with
But the brain’s plasticity is more remarkable thanneural tissue!
that. And here are some examples of its power to“He was a married father of 2 children, and
change adaptively.worked as a civil servant,” Dr Lionel Feuillet and
Blindfolding Experimentscolleagues at the Universite de la Mediterranee in
Just five days of blindfolding in normal sighted adultsMarseille wrote in a letter to the The Lancet medical
leads to the occipital lobe processing information forjournal.
touch and auditory (sound) processing - functions
normally performed by the parietal and temporalImage: Feuillet et al/The Lancet
lobes. It begins to light up in brain imaging studies,Almost all that neuroscientists know about brain
with touch and sound stimuli! This is a rapid,anatomy and function are turned on their head in
temporary rearrangement of brain structure andthese extraordinary cases. Many neurologists feel
function, designed to adapt to new demands. Thethat this is a tribute to the brain's incredible plasticity
occipital lobe returns to normal functioning once theand its built in ‘redundancy’- the idea that
blindfold is removed.much brain tissue has a ‘backup’ function.
Memory and Expertise: taxi drivers and musiciansOthers disagree.  Patrick Wall, professor of anatomy
When you become an expert at something, theat University College, London states “To talk of
areas in your brain that deal with this kind of skillredundancy is a cop-out to get around something
increase in volume.  For example London taxi driversyou don't understand”.
– who have a highly developed memory forOne way or another, it is clear that the brain has
routes through London - have been shown to have aamazing powers of plasticity. And the research tells
larger hippocampus in the temporal lobe than Londonus that our longer-term commitments in life - what
bus drivers. The hippocampus is specialized for spatialskills we invest time into acquiring, what talents we
coding in navigation.want to cultivate, and what we want to learn in
Brain reorganization has also been shown in musicians.depth - will result in profound changes in the very
There are several areas of the brain involved instructure and organisation of our brains.
playing music – in the frontal lobe, parietal lobe