Study of Human and Monkey Brains Reveals Surprising Similarity Yet Major Differences

Brains of humans and monkeys are remarkably similar in how they are organized, according to new research in the journal Neuron, which reports that the regions in the brain that control language and complex thought processes have similar connectivity in both species.

Lead author Franz-Xaver Neubert of the University of Oxford, in the UK, said that the findings may provide valuable insights into the evolutionary process that established both the similarities and differences between primates and humans.

Neubert and his colleagues' research centers around a brain region known as the ventrolateral frontal cortex, a region known to be important for cognitive processes including language, cognitive flexibility, and decision-making.

"It has been argued that to develop these abilities, humans had to evolve a completely new neural apparatus; however others have suggested precursors to these specialized brain systems might have existed in other primates," Neubert said.

Neubert and his team analyzed the brains of 25 humans and 25 macaques using non-invasive MRI techniques, finding a surprising number of similarities in ventrolateral frontal cortex connectivity and the brain region's architecture.

These similarities suggest that some cognitive abilities that are unique to humans "may rely on an evolutionarily conserved neural apparatus that initially supported different functions," the researchers said in a statement.

The research also highlighted some key differences in the brain regions of humans and macaques, such as the ventrolateral frontal cortex circuits in the two species being different in the way that they interact with brain areas involved with hearing.

"This could explain why monkeys perform very poorly in some auditory tasks and might suggest that we humans use auditory information in a different way when making decisions and selecting actions," Neubert said.

The research also revealed that a brain region known in humans as the lateral frontal pole in humans does not seem to have an equivalent area in the monkey. That regions is involved with strategic planning, decision-making, and multi-tasking abilities.

"This might relate to humans being particularly proficient in tasks that require strategic planning and decision making as well as 'multi-tasking,'" Neubert said.

Additionally, some of the observed brain regions that were similar in humans and monkeys "are thought to play roles in psychiatric disorders such as attention deficit hyperactivity disorder, obsessive compulsive disorder, and substance abuse."

The researchers suggest more study into the behavior of these brain networks that are altered by disorders may lead to therapeutic insights.