A core principle of neuroscience was shaken this week, when it was shown that an area of the brain continues to grow in adults.
Popular opinion in neuroscience holds that your brain is fully grown by early adulthood, after which cells and connections are lost, leaving only those that are useful to you.
But a pair of studies published in Science and Cerebral Cortex used a new combination of imaging techniques to reveal a more subtle picture. They looked at a brain region that specialises in recognising faces called the fusiform face area, which is only found in humans and great apes.
The researchers compared children aged 5-12 and adults aged 22-28, using two types of magnetic resonance imaging (MRI), one that measures blood flow and another that measures the ratio of tissue to water. Studying these two age ranges allowed the scientists to look at how the brain changes from childhood to adulthood.
The neuroscientists found tissue growth in the face region of the adult brains, linked to an improvement in the ability to recognise faces. “We actually saw that tissue is proliferating,” says Jesse Gomez, a graduate student at Stanford University. “Many people assume that tissue is lost slowly as you get older. We saw the opposite.”
As well as linking brain growth to changes in brain function, the work may also lead to insights for the two per cent of adults who are unable to recognise faces, a disorder known as prosopagnosia, or facial blindness.
“If you had told me five or 10 years ago that we’d be able to actually measure tissue growth in vivo, I wouldn’t have believed it,” says Kalanit Grill-Spector, senior author of both papers and director of Stanford University’s Vision & Perception Neuroscience Lab. “It shows there are actual changes to the tissue that are happening throughout your development. I think this is fantastic.”