AAP: What we see when we peek into a child’s brain

October 13, 2008

“The mind is what the brain does,” said Massachusetts Institute of Technology’s John D. E. Gabrieli, PhD, leading off Sunday’s connected plenary sessions on the brain and early childhood development. His focus was on how functional magnetic resonance imaging (fMRI) has changed what we know about how child brains differ from adult brains.

“The mind is what the brain does,” said Massachusetts Institute ofTechnology’s John D. E. Gabrieli, PhD, leading off Sunday’s connectedplenary sessions on the brain and early childhood development. His focus was onhow functional magnetic resonance imaging (fMRI) has changed what we know abouthow child brains differ from adult brains.

To collect control information, Gabrieli and associates first did fMRI tests onhealthy volunteers. One of the subjects, a 9-year-old girl, wrote a thank-you letter (with drawing) saying how fun it was to be a “ginny pig,” and helpother kids to boot.

Neurologists know that the medial temporal lobe is an important part of memorydevelopment: when it’s damaged (or in one extreme case removed) new memoriesare very difficult to create. fMRi has revealed almost no difference between achild, adolescent, and adult in use of this lobe.

Where they find big changes is the prefrontal cortex. And, contrary to the layidea that children learn better than adults, it found that adolescents use theprefrontal cortex more with age, and adults use it more than teens.

Unlike computers, there’s no single “hard drive” for memories.Object recognition takes place in the lateral occipital complex (LOC). All threeages of brains use this area equally.

Place recognition, however, takes place in the parahippocampal place area (PPA).And facial recognition has its own section as well, the fusiform face area (FFA).Both PPA and FFA follow the prefrontal cortex’s lead, working better withage. This lets child brains not have to develop all its abilities at once, andfocus on object recognition before faces of places.

fMRI has also been used successfully to track dyslexia treatment. Dyslexia, thankspartly to fMRI findings, is understood to be an auditory problem rather than avisual problem. Since the phonemic awareness develops before the orthographicawareness, without the first the second is quite limited.

The brains of children with dyslexia, when they try to read, show little activityin the Broca’s and Wernicki’s regions, which are connected to thoseauditory and language controls of the brain. But after treatment, their brainslook identical to the control fMRI scans, with Broca and Wernicki glowing with activity. The training “rewired” thebrains, allowing them to think without the biological roadblock.