This brain region keeps growing in adulthood


The part of the brain that specializes in recognizing faces becomes denser with tissue over time, new research finds. The discovery is surprising to researchers, because brain development from childhood into adulthood was long thought to happen mostly through the pruning of synapses, the connections between neurons. In other words, the brain was thought to develop by becoming more streamlined, not by growing new tissue.
The study also showed that these changes in brain structure correlated with the ability to recognize faces. In general, adults are better at recognizing faces than children are, said study leader Jesse Gomez, a doctoral candidate in neuroscience at Stanford University.
But development is personalized. “There are some kids that have adult-like tissue values, but those kids also have adult-like brain function,” Gomez told Live Science. Likewise, some adults who were bad at recognizing faces showed child-like density in their face-recognition region, he said.
The textbook explanation of brain development is that infants are born with a riot of neurons and connections that get snipped away over time, Gomez said. Useful connections strengthen, while those that are underutilized get pruned. As a result, the brain becomes more efficient. This process certainly takes place over the first three years of life, Gomez said, but little is known about development after age 3. He and his colleagues are tackling the question by scanning the brains of elementary-school children again and again over time, and comparing those children’s brains to the brains of young adults.
While comparing the child brains with the adult brains, the researchers found increasing density with age in the posterior part of a brain region called the fusiform face area, located in the visual cortex, near the back of the brain. This brain region specializes in differentiating human faces.
To detect these changes in density, researchers used a method called qualitative magnetic resonance imaging (qMRI). Standard MRI can differentiate between different brain tissues, like white matter and gray matter, Gomez said, but it can’t give any sort of absolute values of brain-cell density that can be compared between people. The new method, qMRI, can. It works by exciting protons in the water in brain tissue. The time it takes for those protons to calm back down to their resting state provides some information about brain density, Gomez explained.

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