Oxford University researchers have identified an area of the human brain
that appears unlike anything in the brains of some of our closest
relatives.
The brain area pinpointed is known to be intimately involved in some
of the most advanced planning and decision-making processes that we
think of as being especially human.
'We tend to think that being
able to plan into the future, be flexible in our approach and learn from
others are things that are particularly impressive about humans. We've
identified an area of the brain that appears to be uniquely human and is
likely to have something to do with these cognitive powers,' says
senior researcher Professor Matthew Rushworth of Oxford University's
Department of Experimental Psychology.
MRI imaging of 25 adult volunteers was used to identify key
components in the ventrolateral frontal cortex area of the human brain,
and how these components were connected up with other brain areas. The
results were then compared to equivalent MRI data from 25 macaque
monkeys.
This ventrolateral frontal cortex area of the brain is
involved in many of the highest aspects of cognition and language, and
is only present in humans and other primates. Some parts are implicated
in psychiatric conditions like ADHD, drug addiction or compulsive
behaviour disorders. Language is affected when other parts are damaged
after stroke or neurodegenerative disease. A better understanding of the
neural connections and networks involved should help the understanding
of changes in the brain that go along with these conditions.
The Oxford University researchers report their findings in the science journal Neuron.
Professor
Rushworth explains: 'The brain is a mosaic of interlinked areas. We
wanted to look at this very important region of the frontal part of the
brain and see how many tiles there are and where they are placed.
'We
also looked at the connections of each tile -- how they are wired up to
the rest of the brain -- as it is these connections that determine the
information that can reach that component part and the influence that
part can have on other brain regions.'
From the MRI data, the
researchers were able to divide the human ventrolateral frontal cortex
into 12 areas that were consistent across all the individuals.
'Each
of these 12 areas has its own pattern of connections with the rest of
the brain, a sort of "neural fingerprint," telling us it is doing
something unique,' says Professor Rushworth.
The researchers were
then able to compare the 12 areas in the human brain region with the
organisation of the monkey prefrontal cortex.
Overall, they were
very similar with 11 of the 12 areas being found in both species and
being connected up to other brain areas in very similar ways.
However,
one area of the human ventrolateral frontal cortex had no equivalent in
the macaque -- an area called the lateral frontal pole prefrontal
cortex.
'We have established an area in human frontal cortex
which does not seem to have an equivalent in the monkey at all,' says
first author Franz-Xaver Neubert of Oxford University. 'This area has
been identified with strategic planning and decision making as well as
"multi-tasking." '
The Oxford research group also found that the
auditory parts of the brain were very well connected with the human
prefrontal cortex, but much less so in the macaque. The researchers
suggest this may be critical for our ability to understand and generate
speech.
The researchers were funded by the UK Medical Research Council.
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