In this schematic, the lateral frontal pole prefrontal cortex is shown as the dark red area at the right.
Oxford University researchers have identified a small zone at the very front of the human brain that looks unlike anything in the brains of some of our closest monkey relatives.
The brain area is considered 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,” said investigator Matthew Rushworth of Oxford University.
The scientists scanned the brains of 25 adult volunteers using Magnetic Resonance Imaging to identify key components of a brain region called the ventrolateral frontal cortex. The results were then compared to equivalent data from 25 macaque monkeys.
The ventrolateral frontal cortex is involved in many of the highest aspects of cognition and language, and is only found in humans and their close relatives such as apes and monkeys, said the investigators, who reported their findings in the research journal Neuron.
“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,” said Rushworth.
“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.”
The researchers divided the human ventrolateral frontal cortex into 12 areas that were consistent across all people. “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,” said Rushworth.
Monkeys shared similar structure in 11 of the 12 areas, with similar connections to other brain areas, the scientists found. But one area of the human ventrolateral frontal cortex had no equivalent in the macaque—an area called the lateral frontal pole prefrontal cortex.
This “does not seem to have an equivalent in the monkey at all,” said co-author Franz-Xaver Neubert of Oxford University. “This area has been identified with strategic planning and decision making as well as “multi-tasking.’“
The 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 speak.